Baird, J. K.

The technical genesis and practice of 8-aminoquinoline therapy of latent malaria offer singular scientific, clinical, and public health insights. The 8-aminoquinolines brought revolutionary scientific discoveries, dogmatic practices, benign neglect, and, finally, enduring promise against endemic malaria. The clinical use of plasmochin—the first rationally synthesized blood schizontocide and the first gametocytocide, tissue schizontocide, and hypnozoitocide of any kind—commenced in 1926. Plasmochin became known to sometimes provoke fatal hemolytic crises. World War II delivered a newer 8-aminoquinoline, primaquine, and the discovery of glucose-6-phosphate dehydrogenase (G6PD) deficiency as the basis of its hemolytic toxicity came in 1956. Primaquine nonetheless became the sole therapeutic option against latent malaria. After 40 years of fitful development, in 2018 the U.S. Food and Drug Administration registered the 8-aminoquinoline called tafenoquine for the prevention of all malarias and the treatment of those that relapse. Tafenoquine also cannot be used in G6PD-unknown or -deficient patients. The hemolytic toxicity of the 8-aminoquinolines impedes their great potential, but this problem has not been a research priority. This review explores the complex technical dimensions of the history of 8-aminoquinolines. The therapeutic principles thus examined may be leveraged in improved practice and in understanding the bright prospect of discovery of newer drugs that cannot harm G6PD-deficient patients.…

Abstract Background To assess the occurrence of Plasmodium ovale wallikeri and Plasmodium ovale curtisi species in travellers returning to Germany, two real-time PCR protocols for the detection and differentiation of the two P. ovale species were compared. Results of parasite differentiation were correlated with patient data. Methods Residual nucleic acid extractions from EDTA blood samples of patients with P. ovale spp. malaria, collected between 2010 and 2019 at the National Reference Centre for Tropical Pathogens in Germany, were subjected to further parasite discrimination in a retrospective assessment. All samples had been analysed by microscopy and by P. ovale spp.-specific real-time PCR without discrimination on species level. Two different real-time PCR protocols for species discrimination of P. o. curtisi and P. o. wallikeri were carried out. Results were correlated with patient data on gender, age, travel destination, thrombocyte count, and duration of parasite latency. Results Samples from 77 P. ovale spp. malaria patients were assessed, with a male:female ratio of about 2:1 and a median age of 30 years. Parasitaemia was low, ranging from few visible parasites up to 1% infected erythrocytes. Discriminative real-time PCRs revealed 41 cases of P. o. curtisi and 36 cases of P. o. wallikeri infections. Concordance of results by the two PCR approaches was 100%. Assessment of travel destinations confirmed co-existence of P. o. curtisi and P. o. wallikeri over a wide range of countries in sub-Saharan Africa. Latency periods for the two P. ovale species were similar, with median values of 56.0 days for P. o. curtisi and 58.0 days for P. o. wallikeri; likewise, there was no statistically significant difference in thrombocyte count with median values of 138.5/µL for patients with P. o. curtisi and 152.0/µL for P. o. wallikeri-infected patients. Conclusions Two different real-time PCR protocols were found to be suitable for the discrimination of P. o. curtisi and P. o. wallikeri with only minor differences in sensitivity. Due to the overall low parasitaemia and the lack of differences in severity-related aspects like parasite latency periods or thrombocyte counts, this study supports the use of P. ovale spp. PCR without discrimination on species level to confirm the diagnosis and to inform clinical management of malaria in these patients.…

Moore, B. R., Benjamin, J. M., Tobe, R., Ome-Kaius, M., Yadi, G., Kasian, B., Kong, C., Robinson, L. J., Laman, M., Mueller, I., Rogerson, S., Davis, T. M. E.

Background: Emerging sulfadoxine-pyrimethamine (SP) malaria parasite resistance has prompted assessment of alternatives for intermittent preventive treatment in pregnancy (IPTp).Objective: To evaluate the tolerability and prophylactic efficacy of azithromycin (AZ) plus piperaquine (PQ) in pregnant Papua New Guinean women.Study design: Open-label, randomized, parallel-group trial.Methods: 122 women (median gestation 26 [range 14-32] weeks) were randomized 1:1 to three daily doses of 1g AZ plus 960 mg PQ tetraphosphate or single-dose SP (4,500 mg sulfadoxine, 225 mg pyrimethamine) based on computer-generated block randomization. Tolerability was assessed to Day 7, and efficacy to Day 42 (when participants were returned to usual care) and at delivery.Results: Data from 119 participants (AZ-PQ n=61, SP n=58) were analyzed. Both regimens were well tolerated, but AZ-PQ was associated with more gastrointestinal side-effects (31%) and dizziness (21%). Eight women (6.7%) were parasitemic at recruitment but all were aparasitemic by 72 hours. There was no difference in blood smear positivity between AZ-PQ and SP up to Day 42 (0% versus 5.2%; relative risk (RR) (95% CI) 0.14 (0.01,2.58), P=0.18; absolute risk reduction (ARR) (95% CI) 5.2 (-1.3,11.6)%) and by the time of delivery (0% versus 8.7%; RR 0.11 (0.01,2.01), P=0.14; ARR 8.7 (-0.2,17.6)%). Of 92 women followed to parturition, 89 (97%) delivered healthy babies and there were three stillbirths (SP n=1, AZ-PQ n=2 (twins)). There was a higher mean±SD live birthweight in the AZ-PQ group (3.13±0.42 versus 2.88±0.55 kg; P=0.016 (mean difference (95% CI) 0.25 (0.02,0.48) kg).Conclusion: AZ-PQ is a promising candidate for IPTp.…

Didier Ménard, David A Fidock

The global fight against malaria has, over the decades, repeatedly been compromised by multidrug-resistant Plasmodium falciparum strains that first emerged in southeast Asia.1 Successively, these parasites have acquired resistance to chloroquine, sulphadoxine-pyrimethamine, mefloquine, and more recently the artemisinins through point mutations or amplification in genes (crt, dhps, dhfr, mdr1, and kelch13).2–6 Following increased resistance to artesunate plus mefloquine,7,8 an early artemisinin-based combined therapy, regional authorities turned increasingly to dihydroartemisinin plus piperaquine.

Abstract Background Understanding the contribution of outdoor-resting Anopheles mosquitoes to residual malaria transmission is important in terms of scaling up vector control towards malaria elimination in South Africa. The aim of this project was to assess the potential role of Anopheles parensis and other Anopheles species in residual malaria transmission, using sentinel surveillance sites in the uMkhanyakude District of northern KwaZulu-Natal Province. Methods Monthly vector surveillance was conducted at the sentinel sites from January 2017 to May 2018. Outdoor-placed clay pot resting traps were used to collect male and female adult Anopheles mosquitoes. All Anopheles gambiae complex and Anopheles funestus group specimens collected were identified to species and all females were screened for Plasmodium falciparum circumsporozoite protein (CSP) by enzyme-linked immunosorbent assay (ELISA). Samples showing infectivity for P. falciparum were further verified by a nested PCR and subsequent DNA sequence analysis. Results From a sample of 491 anophelines, Anopheles arabiensis (n = 228) and An. parensis (n = 194) were the most abundant. Other species collected included Anopheles merus (n =11), Anopheles quadriannulatus (n = 10), Anopheles leesoni (n = 29), Anopheles rivulorum (n =18), and Anopheles vaneedeni (n =1). Of the 317 female specimens screened for P. falciparum CSP, one Anopheles arabiensis and one An. parensis showed positive by ELISA and Plasmodium nested PCR. For the An. parensis specimen, confirmation of its species identity was based on sequence analysis of the ITS2 region, and the presence of P. falciparum DNA was further confirmed by sequence analysis. Conclusions Anopheles parensis is a potential vector of malaria in South Africa although its contribution to transmission is likely to be minimal at best owing to its strong zoophilic tendency. By contrast, An. arabiensis is a major vector that is primarily responsible for the bulk of residual malaria transmission in South Africa. As all recently collected sporozoite-positive Anopheles mosquitoes were found in outdoor-placed resting traps, it is necessary to introduce interventions that can be used to control outdoor-resting vector populations while maintaining the efficacy of South Africa’s indoor house spraying operations.…

Abstract Background More than 200 medicinal plants including Euphorbia abyssinica are utilized for treatment of malaria in Ethiopian traditional medical practices. However, the safety, efficacy and quality of these medicinal plants are largely unknown. Pharmacological and toxicological investigations of these plants are among the prioritized issues in every country. The aim of this study was, therefore, to evaluate the anti-malarial activity of Euphorbia abyssinica root extract against Plasmodium berghei infection in mice. Methods The fresh roots of Euphorbia abyssinica were identified and collected. They were dried and extracted by 80% methanol using maceration. Acute toxicity of the extract was done using female Swiss albino mice. Anti-malarial activity of the extract was done by a standard 4-day suppressive test using chloroquine-sensitive Plasmodium berghei. Twenty-five male Swiss albino mice were randomly grouped into 5 groups of 5 mice each. Group I was treated with distilled water (10 ml/kg), group II, III, and IV were treated with 200, 400, and 600 mg/kg of extract, respectively and group V was treated with chloroquine (25 mg/kg). The level of parasitaemia, survival time, and variation in weight were utilized to determine the anti-malarial activity of the extract. Data was analysed using ANOVA followed by Tukey test. Results The plant extract did not show any sign of toxicity and mortality at 2000 mg/kg. The 4-day chemosuppressive anti-malarial activities produced by the crude extract were 66.87% (P 

Dacheux, M., Sinou, V., Payre, C., Jeammet, L., Parzy, D., Grellier, P., Deregnaucourt, C., Lambeau, G.

The human group IIA secreted phospholipase A2 (hGIIA sPLA2) is increased in the plasma of malaria patients but its role is unknown. In parasite culture with normal plasma, hGIIA is inactive against Plasmodium falciparum, contrasting with hGIIF, hGV and hGX sPLA2s that readily hydrolyze plasma lipoproteins, release non-esterified fatty acids (NEFAs) and inhibit parasite growth. Here, we revisited the anti-Plasmodium activity of hGIIA in conditions closer to malaria physiopathology where lipoproteins are oxidized. In parasite culture containing oxidized lipoproteins, hGIIA sPLA2 was inhibitory with an IC50 value of 150.0 ± 40.8 nM, in accordance with its capacity to release NEFAs from oxidized particles. With oxidized lipoproteins, hGIIF, hGV and hGX sPLA2s were also more potent, by 4.6-, 2.1- and 1.9-fold, respectively. Using specific immunoassays, we found that hGIIA sPLA2 is increased in plasma from 41 patients with malaria over healthy donors (median (IQR): 1.6 (0.7-3.4) nM, versus 0.0 (0.0-0.1) nM, respectively; P

Melissa D Conrad, Philip J Rosenthal

Antimalarial drug resistance, in particular resistance to Plasmodium falciparum, challenges the treatment and control of malaria. In this Review, we summarise evolving patterns of antimalarial drug resistance in Africa. Resistance to aminoquinolines and antifolates is long-standing, yet with greatly decreased use of chloroquine to treat malaria, the prevalence of resistance to chloroquine has decreased. Resistance to antifolates, which are used to prevent malaria in some settings, remains widespread.

Abstract Background New national malaria strategic plans (NMSPs) should build upon the achievements and challenges identified during the implementation of previous plans, but there is limited research on the transition process between NMSPs. This study aims to fill this gap through an assessment of NMSPs across sub-Saharan Africa. Methods The study reviewed the two most recent NMSPs for selected sub-Saharan African countries. Targets for six core malaria indicators were extracted from each NMSP and compared to the coverage achieved according to corresponding population-based surveys completed near the end of the NMSP term. Implementation challenges and proposed solutions identified through the NMSP analysis were documented. The current NMSP was reviewed to determine whether proposed solutions had been integrated into the strategy. Results Twenty-two countries in sub-Saharan Africa were included in the assessment. Of the 135 verified targets, only 4 were achieved. No country reached more than one of the six targets assessed in each NMSP. Despite this low success rate, only four of the 22 countries lowered a subsequent target, with most setting the next target at an equal or greater level. Most NMSPs identified solutions to address implementation challenges faced, but the solutions were not always fully incorporated in the new strategy. Conclusions The results show a disconnect between NMSPs. Most targets were set according to global goals rather than the individual country’s previous achievements and limitations. This indicates a need to revise the NMSP development process to guide programmes in defining targets based on their country context and incorporate strategies to address challenges identified in the previous NMSP. This will allow countries to set and meet achievable targets as they work toward global goals.…

Abstract Background Insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are effective for malaria prevention and are designed to provide nearly 5 years of mosquito protection. However, many ITNs and LLINs become damaged and ineffective for mosquito bite prevention within 1 to 2 years in field conditions. Non-adherence to recommended bed net care and repair practices may partially explain this shortened net longevity. Methods Using data from a cross-sectional study, a net care adherence score was developed and adherence to net care practices described from two regions of western Kenya. Relationships between attitudes and environmental factors that influence net longevity were measured with adherence to bed net care practices. Results While overall care practices are highly adherent particularly in the highlands, practices related to daily storage, washing frequency, and drying location need improvement in the lowlands. Seventy-seven percent of nets in the lowlands were washed 

S. P. Nowak et al.

Costanza Tacoli, Prabhanjan P. Gai, Konrad Siegert, Jakob Wedam, Suyamindra S. Kulkarni, Rashmi Rasalkar, Archith Boloor, Animesh Jain, Chakrapani Mahabala, Shantaram Baliga, Damodara Shenoy, Pramod Gai, Rajeshwari Devi and Frank P. Mockenhaupt

Abstract. India accounts for approximately half of the global Plasmodium vivax cases, but information as to the presence of chloroquine (CQ) resistance is scarce. In an observational study in Mangaluru, south-western India, of 116 vivax malaria patients analyzed, 89.5% (102/114) had cleared parasitemia on days two or three of CQ treatment. Two remaining patients presented on days four and five without parasitemia. One hundred eight isolates of these 116 patients were successfully sequenced for pvmdr1 polymorphisms. Eight non-synonymous polymorphisms but no wild-type isolate were detected. Ten pvmdr1 haplotypes were observed with mutations T958M and F1076L occurring in all isolates, whereas the candidate CQ resistance marker Y976F was present in one isolate only. Pvmdr1 polymorphisms were not associated with early parasite clearance. The high proportion of early parasite clearance and the virtual absence of pvmdr1 Y976F and of sextuple pvmdr1 mutants suggest that CQ in the study area is still sufficiently effective. However, the abundance of pvmdr1 mutations in the local parasite population warrants monitoring.…

Abstract Background In recent years, the scale-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) has greatly reduced malaria transmission. However, malaria remains a global public health concern with the majority of the disease burden in sub-Saharan Africa. Insecticide resistance is a growing problem among Anopheles vector populations, with potential implications for the continued effectiveness of available control interventions. Improved understanding of current resistance levels and underlying mechanisms is essential to design appropriate management strategies and to mitigate future selection for resistance. Methods Anopheles gambiae sensu lato mosquitoes were collected from three villages in Faranah Prefecture, Guinea and their levels of susceptibility to seven insecticides were measured using CDC resistance intensity bioassays. Synergist assays with piperonyl butoxide (PBO) were also undertaken to assess the role of elevated mixed-function oxidases in resistance. Five hundred and sixty-three mosquitoes underwent molecular characterization of vector species, presence of target site mutations (L1014F kdr, N1575Y and G119S Ace-1), Plasmodium falciparum infection, and relative expression of three metabolic genes (CYP6M2, CYP6P3 and GSTD3). Results In Faranah, resistance to permethrin and deltamethrin was observed, as well as possible resistance to bendiocarb. All assayed vector populations were fully susceptible to alpha-cypermethrin, pirimiphos-methyl, clothianidin and chlorfenapyr. Plasmodium falciparum infection was detected in 7.3% (37/508) of mosquitoes tested. The L1014F kdr mutation was found in 100% of a sub-sample of 60 mosquitoes, supporting its fixation in the region. The N1575Y mutation was identified in 20% (113/561) of individuals, with ongoing selection evidenced by significant deviations from Hardy–Weinberg equilibrium. The G119S Ace-1 mutation was detected in 62.1% (18/29) of mosquitoes tested and was highly predictive of bendiocarb bioassay survival. The metabolic resistance genes, CYP6M2, CYP6P3 and GSTD3, were found to be overexpressed in wild resistant and susceptible An. gambiae sensu stricto populations, compared to a susceptible G3 colony. Furthermore, CYP6P3 was significantly overexpressed in bendiocarb survivors, implicating its potential role in carbamate resistance in Faranah. Conclusions Identification of intense resistance to permethrin and deltamethrin in Faranah, is of concern, as the Guinea National Malaria Control Programme (NMCP) relies exclusively on the distribution of pyrethroid-treated LLINs for vector control. Study findings will be used to guide current and future control strategies in the region.…

Abstract Background Malaria transmission is high in western Kenya and the asymptomatic infected population plays a significant role in driving the transmission. Mathematical modelling and simulation programs suggest that interventions targeting asymptomatic infections through mass testing and treatment (MTaT) or mass drug administration (MDA) have the potential to reduce malaria transmission when combined with existing interventions. Objective This paper describes the study site, capacity development efforts required, and lessons learned for implementing a multi-year community-based cluster-randomized controlled trial to evaluate the impact of MTaT for malaria transmission reduction in an area of high transmission in western Kenya. Methods The study partnered with Kenya’s Ministry of Health (MOH) and other organizations on community sensitization and engagement to mobilize, train and deploy community health volunteers (CHVs) to deliver MTaT in the community. Within the health facilities, the study availed staff, medical and laboratory supplies and strengthened health information management system to monitor progress and evaluate impact of intervention. Results More than 80 Kenya MOH CHVs, 13 clinical officers, field workers, data and logistical staff were trained to carry out MTaT three times a year for 2 years in a population of approximately 90,000 individuals. A supply chain management was adapted to meet daily demands for large volumes of commodities despite the limitation of few MOH facilities having ideal storage conditions. Modern technology was adapted more to meet the needs of the high daily volume of collected data. Conclusions In resource-constrained settings, large interventions require capacity building and logistical planning. This study found that investing in relationships with the communities, local governments, and other partners, and identifying and equipping the appropriate staff with the skills and technology to perform tasks are important factors for success in delivering an intervention like MTaT.…

Abstract Background It is estimated that over a third of the world population is infected by malaria and helminthiases mainly among communities with high poverty indices. The distribution of these parasitic infections overlaps in many epidemiological settings and have varying outcomes in the host. In this paper we report the prevalence of malaria and intestinal helminthiases coinfections among malaria suspected patients and the association of helminthiases with the occurrence of malaria and its outcomes in Wondo Genet, southern Ethiopia. Methods In a cross-sectional study conducted from December 2009 to July 2010 in Kella, Aruma and Busa Health Centers in Wondo Genet, a total of 427 consenting febrile patients were screened for malaria and intestinal helminths infections. Malaria parasite detection and quantification were done using Giemsa stained thick and thin blood films. Helminth infections were screened and quantified by Kato-Katz thick smear method. Haemoglobin level was assessed using haemocue machine (HemoCue HB 201+). Difference in proportions and means were tested by Student’s t test and ANOVA while logistic regression analysis was used to determine the association between variables. Results Of the total examined, 196 (45.90%) were positive for at least one helminth infection while 276 (64.64%) were positive for malaria. The prevalence of Plasmodium falciparum and P. vivax infections were 47.31 and 16.62%, respectively. The most common helminth parasites detected were Ascaris lumbricoides (33.96%), Trichuris trichiura (21.55%), Schistosoma mansoni (13.35%), and hookworms (6.79%). The overall malaria-helminthiases coinfection was 33.96%. The prevalence of anaemia was 43.12%. Helminthiases coinfection showed a positive correlation with the occurrence of malaria (AOR = 2.17, 95% CI: 1.44–3.28; P 

Following publication of the original article [1], the authors advised of two errors present in the article: one concerning two author names and the other missing funding details.…

Rob W van der Pluijm, Mallika Imwong, Nguyen Hoang Chau, Nhu Thi Hoa, Nguyen Thanh Thuy-Nhien, Ngo Viet Thanh, Podjanee Jittamala, Borimas Hanboonkunupakarn, Kitipumi Chutasmit, Chalermpon Saelow, Ratchadaporn Runjarern, Weerayuth Kaewmok, Rupam Tripura, Thomas J Peto, Sovann Yok, Seila Suon, Sokunthea Sreng, Sivanna Mao, Savuth Oun, Sovannary Yen, Chanaki Amaratunga, Dysoley Lek, Rekol Huy, Mehul Dhorda, Kesinee Chotivanich, Elizabeth A Ashley, Mavuto Mukaka, Naomi Waithira, Phaik Yeong Cheah, Richard J Ma

Dihydroartemisinin-piperaquine is not treating malaria effectively across the eastern Greater Mekong subregion. A highly drug-resistant P falciparum co-lineage is evolving, acquiring new resistance mechanisms, and spreading. Accelerated elimination of P falciparum malaria in this region is needed urgently, to prevent further spread and avoid a potential global health emergency.

R Matthew Chico, Jorge Cano

Malaria in pregnancy is a leading cause of adverse pregnancy outcomes in low-income and middle-income countries.1 WHO recommends intermittent preventive treatment (IPT) with sulphadoxine–pyrimethamine in areas of Africa where there is moderate to high transmission of Plasmodium falciparum, the most prevalent malaria species in the region. However, parasite sensitivity to sulphadoxine–pyrimethamine is compromised, particularly in parts of east Africa, prompting trials of IPT with dihydroartemisinin–piperaquine.

Abstract Background Malaria vector control is dependent on chemical insecticides applied to walls by indoor residual spraying or on long-lasting insecticidal nets. The emergence and spread of insecticide resistance in major malaria vectors may compromise malaria control and elimination efforts. The aim of this study was to estimate a diagnostic dose for chlorfenapyr (class: pyrrole) and clothianidin (class: neonicotinoid) and assess the baseline susceptibility of three major Anopheles malaria vectors of western Kenya to these two insecticides. Methods The Centers for Disease Control and Prevention (CDC) bottle assay was used to determine the diagnostic doses of chlorfenapyr and clothianidin insecticides against the susceptible Kisumu strain of Anopheles gambiae. Probit analysis was used to determine the lethal doses at which 50% (LD50) and 99% (LD99) of the susceptible mosquitoes would be killed 24, 48 and 72 h following exposure for 1 h. Insecticidal efficacy of chlorfenapyr, clothianidin and the pyrethroid deltamethrin was then evaluated against field collected female Anopheles mosquitoes sampled from Nyando, Bumula and Ndhiwa sub-Counties in western Kenya. Members of Anopheles funestus and An. gambiae complexes were identified using polymerase chain reaction (PCR). Results The determined diagnostic doses of chlorfenapyr and clothianidin insecticides were 50 µg/bottle and 150 µg/bottle, respectively, for An. gambiae, Kisumu strain. When exposed to the diagnostic dose of each insecticide, Anopheles malaria vector populations in western Kenya were susceptible to both insecticides with 100% mortality observed after 72 h. Mortality of mosquitoes exposed to deltamethrin increased over time but did not reach 100%. Mortality of Anopheles arabiensis from Nyando exposed to deltamethrin was 83% at 24 h, 88% at 48 h and 94.5% at 72 h while An. funestus from Ndhiwa was 89% at 24 h, 91.5% at 48 h and 94.5% at 72 h. Conclusion Mosquitoes of western Kenya, despite being resistant to pyrethroids, are susceptible to chlorfenapyr and clothianidin. Field evaluations of the formulated product are needed.…

Abstract Background Despite recent strides made towards reducing the emergence of artemisinin resistance, inappropriate dispensing practices for anti-malarials in both private and public sectors affect treatment outcomes negatively. In Ghana, private retail pharmacies are the most accessible health facilities for managing diseases of common occurrence. However, there is growing concern about the number of patients harmed by dispensing errors in the management of malaria in retail pharmacies. Although considerable work has been done in this area, several questions regarding dispensing practices remain unanswered. This study, therefore, sought to investigate the predictors of appropriate dispensing practices for anti-malarials in community pharmacies in the La Nkwantanang-Madina municipality of Greater Accra, Ghana. Methods A cross-sectional analytic study was conducted in sixty-one randomly selected community pharmacies in the La Nkwantanang-Madina. Data from 230 clients and 106 dispensers were analysed. It was checked for internal consistency and completeness then entered and analysed using STATA I/C version 14.0. Frequencies, Chi square tests, and logistic regression analyses were conducted, accounting for clustering. Results and discussion Of the 106 dispensers interviewed, 71.4% were medicine counter assistants. The mean age of dispensers was 30.4 years (SD 8.8). Over 88.0% of clients were advised to complete the full course of their anti-malarials. However, the 8-h loading dose principle for artemether-lumefantrine was not explained to 88.3% of the clients. More than half of the clients (52.2%) were given appropriate dispensing information on anti-malarial use. Most clients (66.1%), were dispensed anti-malarials without malaria tests. Dispensers with more than a 10-years experience were less likely to dispense artemisinin-based combinations appropriately relative to dispensers with less than 2 years experience (AOR = 0.04, 95% CI 0.002–0.802 p-value = 0.036) while pharmacy interns were about 19 times more likely (AOR = 18.5, 95% CI 1.40–245.6 p-value = 0.03) to dispense artemisinin-based combinations appropriately compared to pharmacists. Conclusion Dispensing practices for anti-malarials is unsatisfactory. There is a need to enforce existing legislation with educational programmes directed towards dispensers especially those with more than 10 years experience. Specific adherence to the World Health Organization Test, Treat and Track initiative should be encouraged to ensure effective use of anti-malarials.…

Abstract Background Ecuador plans to eliminate malaria by 2020, and the country has already seen a decrease in the number of cases from more than 100,000 in 2000 to only 618 in 2015. Around 30% of malaria infections in Ecuador are caused by Plasmodium falciparum. Most malaria population genetics studies performed in Latin America, especially in the Pacific Coast, indicate a high clonality and a clear structure of P. falciparum populations. It was shown that an outbreak of P. falciparum in northwest Ecuador was the result of a clonal expansion of parasites circulating at low levels in the country or re-invading Ecuador from neighbouring territories. However, general characteristics of P. falciparum circulating in the northwest coast of Ecuador have not been determined. The main goal of this study was to genetically characterize the population structure of P. falciparum in coastal Ecuadorian localities bordering with Colombia. Methods Molecular investigation of 41 samples collected from 2013 to 2016 in San Lorenzo County, northwest Ecuador was performed using seven neutral microsatellite markers. Results The genetic population structure of P. falciparum in northwest Ecuador is clearly defined as three different genetic groups previously reported in Ecuador, Peru and Colombia. Conclusions The limited number of P. falciparum clonal types that are circulating in northwest Ecuador, are related to ancestral parasite clonal lineages reported in the Pacific Coast. These parasites could be a product of migration from neighbouring regions or residual clonal types circulating in the country in low proportions. Studies of the genetic characterization of P. falciparum in eliminating areas help determine the possible origin of parasites in order to create strategies to prevent the entrance of new lineages and achieve local elimination of malaria.…

Abstract Background Natural exposure to gametocytes can result in the development of immunity against the gametocyte by the host as well as genetic diversity in the gametocyte. This study evaluated the quantity and quality of natural immune responses against a gametocyte antigen, Pfs230 as well as the prevalence and diversity of gametocytes circulating in children living in two communities in southern Ghana. Methods Whole blood (2.5 ml) was collected from 137 non-febrile school children aged between 6 and 12 years old quarterly for a 6-month period. A drop of blood was used to prepare thick and thin blood films for parasite prevalence and density estimation. Subsequently, stored plasma samples were used in ELISAs assays to measure antibody responses and avidity against Pfs230. RNA was extraction from Trizol preserved packed cells and subsequently converted to complementary DNA (cDNA) which was used for reverse transcriptase PCR (RT-PCR) to determine gametocytes prevalence and diversity. Results Gametocyte carriage in the peak season (July) determined by Pfg377 RT-PCR was 49.2% in Obom and 22.2% in Abura, and was higher than that determined by microscopy. Gametocyte diversity was low and predominated by the same allele at both sites. The relative avidity index for antibodies measured in Abura was higher than that recorded in Obom at all time points although Pfs230 IgG concentrations were significantly high (P 

Laurens M, Berry A, Travassos M, et al.

AbstractDirect venous inoculation (DVI) of 3.2x103 aseptic, purified, cryopreserved, vialed Plasmodium falciparum (Pf) strain NF54 sporozoites, PfSPZ Challenge (NF54), has been used for controlled human malaria infection (CHMI) in the U.S., 4 European and 6 African countries. In non-immunes, this results in 100% infection rates. We conducted a double blind, randomized, dose escalation study to assess the infectivity of the 7G8 clone of Pf (PfSPZ Challenge [7G8]). Results showed dose-dependent infectivity from 43% for 8x102 PfSPZ to 100% for 4.8x103 PfSPZ. PfSPZ Challenge (7G8) will allow for more complete assessment by CHMI of anti-malarial vaccines and drugs.

Rukhsana Ahmed, Jeanne R Poespoprodjo, Din Syafruddin, Carole Khairallah, Cheryl Pace, Theda Lukito, Sylvia S Maratina, Puji B S Asih, Maria A Santana-Morales, Emily R Adams, Vera T Unwin, Christopher T Williams, Tao Chen, James Smedley, Duolao Wang, Brian Faragher, Richard N Price, Feiko O ter Kuile

IST was associated with a lower prevalence of malaria than SST at delivery, but the prevalence of malaria in this group was also lower at enrolment, making interpretation of the effect of IST challenging. Further studies with highly sensitive malaria rapid diagnostic tests should be considered. Monthly IPT with dihydroartemisinin–piperaquine is a promising alternative to SST in areas in the Asia-Pacific region with moderate or high transmission of malaria.

William L Hamilton, Roberto Amato, Rob W van der Pluijm, Christopher G Jacob, Huynh Hong Quang, Nguyen Thanh Thuy-Nhien, Tran Tinh Hien, Bouasy Hongvanthong, Keobouphaphone Chindavongsa, Mayfong Mayxay, Rekol Huy, Rithea Leang, Cheah Huch, Lek Dysoley, Chanaki Amaratunga, Seila Suon, Rick M Fairhurst, Rupam Tripura, Thomas J Peto, Yok Sovann, Podjanee Jittamala, Borimas Hanboonkunupakarn, Sasithon Pukrittayakamee, Nguyen Hoang Chau, Mallika Imwong, Mehul Dhorda, Ranitha Vongpromek, Xin Hui S Chan, Richard J

After emerging and circulating for several years within Cambodia, the P falciparum KEL1/PLA1 co-lineage diversified into multiple subgroups and acquired new genetic features, including novel crt mutations. These subgroups have rapidly spread into neighbouring countries, suggesting enhanced fitness. These findings highlight the urgent need for elimination of this increasingly drug-resistant parasite co-lineage, and the importance of genetic surveillance in accelerating malaria elimination efforts.

Abstract Background Ensuring universal access to malaria diagnosis and treatment is a key component of Pillar 1 of the World Health Organization Global Technical Strategy for Malaria 2016–2030. To achieve this goal it is essential to know the types of facilities where the population seeks care as well as the malaria service readiness of these facilities in endemic countries. Methods To investigate the utilization and provision of malaria services, data on the sources of advice or treatment in children under 5 years with fever from the household-based Demographic and Health Surveys (DHS) and on the components of malaria service readiness from the facility-based Service Provision Assessment (SPA) surveys were examined in Malawi, Senegal and Tanzania. Facilities categorized as malaria-service ready were those with: (1) personnel trained in either malaria rapid diagnostic testing (RDT), microscopy or case management/treatment of malaria in children; (2) national guidelines for the diagnosis and treatment of malaria; (3) diagnostic capacity (available RDT tests or microscopy equipment as well as staff trained in its use); and, (4) unexpired artemisinin-based combination therapy (ACT) available on the day of the survey. Results In all three countries primary-level facilities (health centre/health post/health clinic) were the type of facility most used for care of febrile children. However, only 69% of these facilities in Senegal, 32% in Malawi and 19% in Tanzania were classified as malaria-service ready. Of the four components of malaria-service readiness in the facilities most frequented by febrile children, diagnostic capacity was the weakest area in all three countries, followed by trained personnel. All three countries performed well in the availability of ACT. Conclusions This analysis highlights the need to improve the malaria-service readiness of facilities in all three countries. More effort should be focused on facilities that are commonly used for care of fever, especially in the areas of malaria diagnostic capacity and provider training. It is essential for policymakers to consider the malaria-service readiness of primary healthcare facilities when allocating resources. This is particularly important in limited-resource settings to ensure that the facilities most visited for care are properly equipped to provide diagnosis and treatment for malaria.…

Abstract Background The Uganda National Malaria Control Programme recognizes the importance of minimizing the effect of malaria among pregnant women. Accordingly, strategies including intermittent preventive treatment of malaria in pregnancy using sulfadoxine-pyrimethamine (IPTp-SP) have been scaled up. Uptake of IPTp-SP among pregnant women in Uganda, aged 15–49 years who had had a live birth 2 years preceding the 2016 Uganda Demographic and Health Survey (UDHS) was determined and factors associated with the uptake of optimal IPTp-SP doses were identified. Methods This was a secondary analysis of the UDHS 2016 dataset. The outcome variable was uptake of IPTp-SP doses among women 15–49 years old who had had a live birth 2 years preceding the survey. Independent variables were residence type, age, marital status, education, wealth status, region of residence, parity, number of antenatal care (ANC) attendance, timing to first ANC visit, and exposure to messages through radio. Logistic regression was used to identify factors associated with the uptake of optimal IPTp-SP doses. Results Uptake of three or more doses of IPTp-SP was 18%. The likelihood of taking optimal doses of IPTp-SP was increased among those who had attained a secondary-level education (aOR: 1.5, 95% CI 1.04–2.15), those who attended ANC ≥ 4 times (aOR: 1.34, 95% CI 1.12–1.60), and those exposed to radio messages (aOR: 1.23, 95% CI 1.02–1.48). Among those in the age category > 34 years (aOR: 0.70, 95% CI 0.53–0.92), and those who attended first ANC in the third trimester of pregnancy (aOR: 0.58, 95% CI 0.38–0.87) the odds of uptake were decreased. Conclusions Education status, exposure to radio messages about health and frequency of ANC attendance were associated with increased uptake while timing of first ANC attendance and being > 34 years were associated with decreased uptake. The findings suggest a need to strengthen behaviour change communication among women of child-bearing age in order to improve uptake of IPTp-SP during pregnancy.…

Paul J. Krezanoski, Data Santorino, Alfred Agaba, Grant Dorsey, David R. Bangsberg and Ryan W. Carroll

Abstract. Long-lasting insecticide-treated bednets are widely used and promoted for malaria control. Limitations in measurement methods have resulted in a poor understanding of how bednets are used in practice. We deployed a novel remote monitoring tool in Uganda to obtain, for the first time, a comprehensive characterization of bednet use in households at risk for malaria. Ten households each used one SmartNet adherence monitor over a commonly used sleeping area for 6 weeks. SmartNet continuously measures and records bednet use every 15 minutes. Bednet use was monitored for a total of 9,258 hours overall, with an average of 42 nights per household (SD: 3.5). Average duration of bednet use was 9 hours 49 minutes per night (SD: 1 hour 56 minutes), and adherence was 85–90% from 2100 to 0600. Bednets were not used at all on 4.5% (19/418) of observation nights. Overall, the average clock time that bednets were unfurled was 2034 (SD: 1 hour 25 minutes) and they were folded up at 0743 (SD: 43 minutes). The rate of interruptions per night observed in all households was 0.23 (86/369), with an average duration of 48 minutes (SD: 49 minutes). There was substantial heterogeneity between households, and some households had consistently poorer adherence relative to others. Variations in bednet use behaviors are a potentially important, and under-researched, component of long-lasting insecticide-treated bednet effectiveness. Remote bednet use monitors can provide novel insights into how bednets are used in practice, helping identify both households at risk of malaria due to poor adherence and also potentially novel targets for improving malaria prevention.…

Dominique Earland, Andrea G. Buchwald, Alick Sixpence, Mabvuto Chimenya, Milius Damson, Karl B. Seydel, Don P. Mathanga, Terrie E. Taylor and Miriam K. Laufer

Abstract. Multiplicity of infection (MOI), the number of unique Plasmodium falciparum parasite genotypes found in one infected individual, may contribute to the development of clinical malaria disease. However, the independent contribution of MOI and parasite density to clinical disease has not been well characterized. We conducted a two-year longitudinal cohort study of adults and children in a high-transmission setting in Malawi to test the hypothesis that increased MOI was independently associated with clinical disease, after accounting for parasite density. Of 1,062 episodes of infection, 477 (44.9%) were associated with symptoms. After controlling for repeated measures within an individual, key demographic factors, and parasite density, there was no association between MOI and clinical disease (OR = 1.02, 95% CI: 0.70–1.51). Although the limited ability to discern MOI in low-density asymptomatic infections may have impacted our results, we conclude that MOI is not an independent risk factor for clinical disease.…

Abstract Background Mass drug administration (MDA) is a suggested mean to accelerate efforts towards elimination and attainment of malaria-free status. There is limited evidence of suitable methods of implementing MDA programme to achieve a high coverage and compliance in low-income countries. The objective of this paper is to assess the impact of this MDA delivery strategy while using coverage measured as effective population in the community and population available. Methods Population-based MDA was implemented as a part of a larger program in a high transmission setting in Uganda. Four rounds of interventions were implemented over a period of 2 years at an interval of 6 to 8 months. A housing and population census was conducted to establish the eligible population. A team of 19 personnel conducted MDA at established village meeting points as distribution sites at every village. The first dose of dihydroartemisinin–piperaquine (DHA-PQ) was administered via a fixed site distribution strategy by directly observed treatment on site, the remaining doses were taken at home and a door-to-door follow up strategy was implemented by community health workers to monitor adherence to the second and third doses. Results Based on number of individuals who turned up at the distribution site, for each round of MDA, effective coverage was 80.1%, 81.2%, 80.0% and 80% for the 1st, 2nd, 3rd and 4th rounds respectively. However, coverage based on available population at the time of implementing MDA was 80.1%, 83.2%, 82.4% and 82.9% for rounds 1, 2, 3 and 4, respectively. Intense community mobilization using community structures and mass media facilitated community participation and adherence to MDA. Conclusion A hybrid of fixed site distribution and door-to-door follow up strategy of MDA delivery achieved a high coverage and compliance and seemed feasible. This model can be considered in resource-limited settings.…

Jones, S., Kay, K., Hodel, E. M., Chy, S., Mbituyumuremyi, A., Uwimana, A., Menard, D., Felger, I., Hastings, I.

Background. Drug efficacy trials monitor the continued efficacy of front-line drugs against falciparum malaria. Over-estimates of efficacy result in a country retaining a failing drug as first-line treatment with associated increases in morbidity and mortality, while under-estimating drug effectiveness leads to removal of an effective treatment with substantial practical and economic implications. Trials are challenging: they require long durations of follow-up to detect drug failures, and patients are frequently re-infected during that period. Molecular correction based on parasite genotypes distinguishes reinfections from drug failures to ensure the accuracy of failure rate estimates. Several molecular correction "algorithms" are proposed, but which is most accurate and/or robust remains unknown.Methods. We used pharmacological modelling to simulate parasite dynamics and genetic signals that occur in patients enrolled in malaria drug clinical trials. We compared estimates of treatment failure obtained from a selection of proposed molecular correction algorithms against the known "true" failure rate in the model.Findings. (i) Molecular correction is essential to avoid substantial over-estimates of drug failure rates. (ii) The current WHO-recommended algorithm consistently under-estimates the true failure rate. (iii) Newly-proposed algorithms produce more accurate failure rate estimates; the most accurate algorithm depends on the choice of drug, trial follow-up length, and transmission intensity. (iv) Long durations of patient follow-up may be counterproductive; large numbers of new infections accumulate and may be misclassified, over-estimating drug failure rate. (v) Our model was highly consistent with existing in vivo data.Interpretation. The current WHO-recommended method for molecular correction and analysis of clinical trials should be re-evaluated and updated.…

Oyong D, Wilson D, Barber B, et al.

AbstractBackgroundComplement-fixing antibodies are important mediators of protection against Plasmodium falciparum malaria. However, complement-fixing antibodies remain uncharacterised for P. vivax malaria. Plasmodium vivax merozoite Surface Protein-3α (PvMSP3α) is a target of acquired immunity and a potential vaccine candidate.MethodsPlasma from children and adults with P. vivax malaria in Sabah, Malaysia, were collected during acute infection, 7 and 28 days following drug treatment. Complement-fixing antibodies and IgM and IgG, targeting three distinctive regions of PvMSP3α were measured by ELISA.ResultsSeroprevalence of complement-fixing antibodies was highest against PvMSP3α Central region (77.6%). IgG1, IgG3, and IgM were significantly correlated with C1q-fixation and both purified IgG and IgM were capable of mediating C1q-fixation to PvMSP3α. Complement-fixing antibody levels were similar between age groups, but IgM was predominant in children and IgG3 more prevalent in adults. Functional antibodies increased following acute infection to 7 days after treatment, however rapidly waned by day 28.ConclusionOur study demonstrates PvMSP3α antibodies acquired during P. vivax infection can mediate complement-fixation and shows the important influence of age in shaping these specific antibody responses. Further studies are warranted to understand the role of these functional antibodies in protective immunity against P. vivax malaria.

Abstract Background The Mindray BC-6800 haematology analyzer (BC-6800) provides a dedicated flag ‘Infected RBC’ (InR) and the number of InR (InR#)/the permillage of InR (InR‰) in routine blood testing as a screening tool for malaria in endemic areas. This study sought to evaluate the effectiveness of the BC-6800 flag parameter for aiding the diagnosis of malaria. Methods A total of 181 samples were tested using the Mindray BC-6800 haematology analyzer, including 117 malaria-infected samples collected from Yunnan, China, and 64 samples from healthy controls. Microscopy examination was conducted as reference when stained thick blood film revealed the presence of malaria parasites identified as Plasmodium vivax and Plasmodium falciparum. The receiver operating characteristic (ROC) curve analysis was developed using Analyse-it v4.92.3. The Kappa value was determined to evaluate the agreement between BC-6800 and light microscopy. Results The sensitivity of InR‰ generated by BC-6800 for P. vivax and P. falciparum was 88.3 and 24.1%, respectively; specificity of InR‰ for malaria parasites was 84.3 and 84.3%, respectively; positive predictive value and negative predictive value was 89.4 and 82.7% for P. vivax, and 52.8 and 60.3% for P. falciparum. There was a strong correlation between ΔWBC and InR‰ (R2 = 0.9731 for P. vivax and R2 = 0.9757 for P. falciparum). There was also a significant correlation between parasitaemia and InR# in P. vivax-infected samples (R2 = 0.734). InR# was evaluated using ROC curve analysis, the area under the ROC curve is 0.95 with a 95% confidence interval of 0.926 to 0.974, and the cut-off value is 0.01 × 109/L for P. vivax. However, the ring stage and the early trophozoite stage of Plasmodium cannot be detected easily on BC-6800, possibly because of the small size and low nucleic acid content of these stages. Conclusions The findings suggest that the flag ‘InR’ and the parameters ‘InR#/InR‰’ provided by the BC-6800 haematology analyzer could be used to screen for malaria in a clinical setting.…

Katherine E Battle, Tim C D Lucas, Michele Nguyen, Rosalind E Howes, Anita K Nandi, Katherine A Twohig, Daniel A Pfeffer, Ewan Cameron, Puja C Rao, Daniel Casey, Harry S Gibson, Jennifer A Rozier, Ursula Dalrymple, Suzanne H Keddie, Emma L Collins, Joseph R Harris, Carlos A Guerra, Michael P Thorn, Donal Bisanzio, Nancy Fullman, Chantal K Huynh, Xie Kulikoff, Michael J Kutz, Alan D Lopez, Ali H Mokdad, Mohsen Naghavi, Grant Nguyen, Katya Anne Shackelford, Theo Vos, Haidong Wang, Stephen S Lim, Christopher J

Our study highlights important spatial and temporal patterns in the clinical burden and prevalence of P vivax. Amid substantial progress worldwide, plateauing gains and areas of increased burden signal the potential for challenges that are greater than expected on the road to malaria elimination. These results support global monitoring systems and can inform the optimisation of diagnosis and treatment where P vivax has most impact.

Daniel J Weiss, Tim C D Lucas, Michele Nguyen, Anita K Nandi, Donal Bisanzio, Katherine E Battle, Ewan Cameron, Katherine A Twohig, Daniel A Pfeffer, Jennifer A Rozier, Harry S Gibson, Puja C Rao, Daniel Casey, Amelia Bertozzi-Villa, Emma L Collins, Ursula Dalrymple, Naomi Gray, Joseph R Harris, Rosalind E Howes, Sun Yun Kang, Suzanne H Keddie, Daniel May, Susan Rumisha, Michael P Thorn, Ryan Barber, Nancy Fullman, Chantal K Huynh, Xie Kulikoff, Michael J Kutz, Alan D Lopez, Ali H Mokdad, Mohsen Naghavi, Gr

High-resolution maps of P falciparum provide a contemporary resource for informing global policy and malaria control planning, programme implementation, and monitoring initiatives. Amid progress in reducing global malaria burden, areas where incidence trends have plateaued or increased in the past 5 years underscore the fragility of hard-won gains against malaria. Efforts towards elimination should be strengthened in such areas, and those where burden remained high throughout the study period.

Abstract Background As areas move closer to malaria elimination, a combination of limited resources and increasing heterogeneity in case distribution and transmission favour a shift to targeted reactive interventions. Reactive case detection (RCD), the following up of additional individuals surrounding an index case, has the potential to target transmission pockets and identify asymptomatic cases in them. Current RCD implementation strategies vary, and it is unclear which are most effective in achieving elimination. Methods OpenMalaria, an established individual-based stochastic model, was used to simulate RCD in a Zambia-like setting. The capacity to follow up index cases, the search radius, the initial transmission and the case management coverage were varied. Suitable settings were identified and probabilities of elimination and time to elimination estimated. The value of routinely collected prevalence and incidence data for predicting the success of RCD was assessed. Results The results indicate that RCD with the aim of transmission interruption is only appropriate in settings where initial transmission is very low (annual entomological inoculation rate (EIR) 1–2 or prevalence approx.

Abstract Background Parasite prevalence has been used widely as a measure of malaria transmission, especially in malaria endemic areas. However, its contribution and relationship to malaria mortality across different age groups has not been well investigated. Previous studies in a health and demographic surveillance systems (HDSS) platform in western Kenya quantified the contribution of incidence and entomological inoculation rates (EIR) to mortality. The study assessed the relationship between outcomes of malaria parasitaemia surveys and mortality across age groups. Methods Parasitological data from annual cross-sectional surveys from the Kisumu HDSS between 2007 and 2015 were used to determine malaria parasite prevalence (PP) and clinical malaria (parasites plus reported fever within 24 h or temperature above 37.5 °C). Household surveys and verbal autopsy (VA) were used to obtain data on all-cause and malaria-specific mortality. Bayesian negative binomial geo-statistical regression models were used to investigate the association of PP/clinical malaria with mortality across different age groups. Estimates based on yearly data were compared with those from aggregated data over 4 to 5-year periods, which is the typical period that mortality data are available from national demographic and health surveys. Results Using 5-year aggregated data, associations were established between parasite prevalence and malaria-specific mortality in the whole population (RRmalaria = 1.66; 95% Bayesian Credible Intervals: 1.07–2.54) and children 1–4 years (RRmalaria = 2.29; 1.17–4.29). While clinical malaria was associated with both all-cause and malaria-specific mortality in combined ages (RRall-cause = 1.32; 1.01–1.74); (RRmalaria = 2.50; 1.27–4.81), children 1–4 years (RRall-cause = 1.89; 1.00–3.51); (RRmalaria = 3.37; 1.23–8.93) and in older children 5–14 years (RRall-cause = 3.94; 1.34–11.10); (RRmalaria = 7.56; 1.20–39.54), no association was found among neonates, adults (15–59 years) and the elderly (60+ years). Distance to health facilities, socioeconomic status, elevation and survey year were important factors for all-cause and malaria-specific mortality. Conclusion Malaria parasitaemia from cross-sectional surveys was associated with mortality across age groups over 4 to 5 year periods with clinical malaria more strongly associated with mortality than parasite prevalence. This effect was stronger in children 5–14 years compared to other age-groups. Further analyses of data from other HDSS sites or similar platforms would be useful in investigating the relationship between malaria and mortality across different endemicity levels.…

Abstract Background Most impact prediction of malaria vector control interventions has been based on African vectors. Anopheles albimanus, the main vector in Central America and the Caribbean, has higher intrinsic mortality, is more zoophilic and less likely to rest indoors. Therefore, relative impact among interventions may be different. Prioritizing interventions, in particular for eliminating Plasmodium falciparum from Haiti, should consider local vector characteristics. Methods Field bionomics data of An. albimanus from Hispaniola and intervention effect data from southern Mexico were used to parameterize mathematical malaria models. Indoor residual spraying (IRS), insecticide-treated nets (ITNs), and house-screening were analysed by inferring their impact on the vectorial capacity in a difference-equation model. Impact of larval source management (LSM) was assumed linear with coverage. Case management, mass drug administration and vaccination were evaluated by estimating their effects on transmission in a susceptible-infected-susceptible model. Analogous analyses were done for Anopheles gambiae parameterized with data from Tanzania, Benin and Nigeria. Results While LSM was equally effective against both vectors, impact of ITNs on transmission by An. albimanus was much lower than for An. gambiae. Assuming that people are outside until bedtime, this was similar for the impact of IRS with dichlorodiphenyltrichloroethane (DDT) or bendiocarb, and impact of IRS was less than that of ITNs. However, assuming people go inside when biting starts, IRS had more impact on An. albimanus than ITNs. While house-screening had less impact than ITNs or IRS on An. gambiae, it had more impact on An. albimanus than ITNs or IRS. The impacts of chemoprevention and chemotherapy were comparable in magnitude to those of strategies against An. albimanus. Chemo-prevention impact increased steeply as coverage approached 100%, whilst clinical-case management impact saturated because of remaining asymptomatic infections. Conclusions House-screening and repellent IRS are potentially highly effective against An. albimanus if people are indoors during the evening. This is consistent with historical impacts of IRS with DDT, which can be largely attributed to excito-repellency. It also supports the idea that housing improvements have played a critical role in malaria control in North America. For elimination planning, impact estimates need to be combined with feasibility and cost-analysis.…

Abstract Background Drug resistance within the major malaria parasites Plasmodium vivax and Plasmodium falciparum threatens malaria control and elimination in Southeast Asia. Plasmodium vivax first-line treatment drug is chloroquine together with primaquine, and the first-line treatment for P. falciparum malaria is artemisinin in combination with a partner drug. Plasmodium vivax and P. falciparum parasites resistant to their respective first-line therapies are now found within Southeast Asia. The resistance perimeters may include high transmission regions of Southern Thailand which are underrepresented in surveillance efforts. Methods This study investigated blood samples from malaria centres in Southern Thailand. Genetic loci associated with drug resistance were amplified and sequenced. Drug resistance associated genes Pvmdr1, Pvcrt-o, Pvdhfr, and Pvdhps were characterized for 145 cases of P. vivax malaria, as well as the artemisinin resistance-associated Pfkelch13 gene from 91 cases of P. falciparum malaria. Results Plasmodium vivax samples from Southern Thai provinces showed numerous chloroquine and antifolate resistance-associated mutations, including SNP and Pvcrt-o K10-insertion combinations suggestive of chloroquine resistant P. vivax phenotypes. A high proportion of the C580Y coding mutation (conferring artemisinin resistance) was detected in P. falciparum samples originating from Ranong and Yala (where the mutation was previously unreported). Conclusions The results demonstrate a risk of chloroquine and antifolate resistant P. vivax phenotypes in Southern Thailand, and artemisinin resistant P. falciparum observed as far south as the Thai–Malaysian border region. Ongoing surveillance of antimalarial drug resistance markers is called for in Southern Thailand to inform case management.…

Zhou, R., Yang, C., Li, S., Zhao, Y., Liu, Y., Qian, D., Wang, H., Lu, D., Zhang, H., Huang, F.

Angola was the main origin country for the imported malaria in Henan Province, China. The antimalarial drug resistance has posed a threat to the control and elimination of malaria. Several molecular markers were confirmed to be associated with the antimalarial drug resistance such as pfcrt, pfmdr1, pfdhfr, pfdhps and K13. This study will evaluate the drug resistance of the 180 imported Plasmodium falciparum isolates from Angola via nested PCR by Sanger sequencing. The prevalence of pfcrt C72V73M74N75K76, pfmdr1 N86Y184S1034N1042D1246, pfdhfr A16N51C59S108D139I164 and pfdhps S436A437A476K540A581 was 69.4%, 59.9%, 1.3% and 6.3%, respectively. Three nonsynonymous (A578S, M579I and Q613E) and one synonymous (R471R) mutation of K13 were found, the prevalence of which was 2.5% and 1.3%, respectively. The single nucleotide polymorphisms (SNPs) in pfcrt, pfmdr1, pfdhfr and pfdhps were generally shown as multiple mutations. The mutant prevalence of pfcrt reduced gradually, but pfdhfr and pfdhps still showed high mutant prevalence, while pfmdr1 was relatively low. The mutation of K13 gene was rare. Molecular surveillance of artemisinin-resistance (ART-resistance) will be as a tool to evaluate the real time efficacy of the artemisinin-based combination therapies (ACTs) and the ART-resistance situation as well.…

Abstract Background Plasmodium vivax transmission in West Africa, dominant for the Duffy-negative blood group, has been increasingly recognized from both local residents as well as international travelers who contracted P. vivax malaria there. However, the relapsing pattern and sensitivity to antimalarial treatment of P. vivax strains originated from this region are largely unknown. There is evidence that the efficacy of primaquine for radical cure of relapsing malaria depends on host factors such as the hepatic enzyme cytochrome P450 (CYP) 2D6. Case presentation A 49-year-old Chinese man was admitted to the Shanglin County Hospital in Guangxi Province, China, on December 19, 2016, 39 days after he returned from Ghana, where he stayed for one and a half years. He was diagnosed by microscopy as having uncomplicated P. vivax malaria. Treatment included 3 days of intravenous artesunate (420 mg total), and 3 days of chloroquine (1550 mg total), and 8 days of primaquine (180 mg total). Although parasites and symptoms were cleared rapidly and he was malaria-negative for almost two months, he suffered four relapses with relapse intervals ranging from 58 to 232 days. The last relapse occurred at 491 days from his first vivax attack. For the first three relapses, he was treated similarly with chloroquine and primaquine, sometimes supplemented with additional artemisinin combination therapies (ACTs). For the last relapse, he was treated with intravenous artesunate, 3 days of an ACT, and 7 days of azithromycin, and had remained healthy for 330 days. Molecular studies confirmed P. vivax infections for all the episodes. Although this patient was diagnosed to have normal glucose-6-phosphate dehydrogenase (G6PD) activity, his CYP2D6 genotype corresponded to a *2A/*36 allele variant suggesting of an impaired primaquine metabolizer phenotype. Conclusions This clinical case suggests that P. vivax malaria originating from West Africa may produce multiple relapses extending beyond one year. The failures of primaquine as an anti-relapse therapy may be attributed to the patient’s impaired metabolizer phenotype of the CYP2D6. This highlights the importance of knowing the host G6PD and CYP2D6 activities for effective radical cure of relapsing malaria by primaquine.…

Abstract Background Measures of malaria burden using microscopy and rapid diagnostic tests (RDTs) in cross-sectional household surveys may incompletely describe the burden of malaria in low-transmission settings. This study describes the pattern of malaria transmission in Ethiopia using serological antibody estimates derived from a nationwide household survey completed in 2015. Methods Dried blood spot (DBS) samples were collected during the Ethiopian Malaria Indicator Survey in 2015 from malarious areas across Ethiopia. Samples were analysed using bead-based multiplex assays for IgG antibodies for six Plasmodium antigens: four human malaria species-specific merozoite surface protein-1 19kD antigens (MSP-1) and Apical Membrane Antigen-1 (AMA-1) for Plasmodium falciparum and Plasmodium vivax. Seroprevalence was estimated by age, elevation and region. The seroconversion rate was estimated using a reversible catalytic model fitted with maximum likelihood methods. Results Of the 10,278 DBS samples available, 93.6% (9622/10,278) had valid serological results. The mean age of participants was 15.8 years and 53.3% were female. National seroprevalence for antibodies to P. falciparum was 32.1% (95% confidence interval (CI) 29.8–34.4) and 25.0% (95% CI 22.7–27.3) to P. vivax. Estimated seroprevalences for Plasmodium malariae and Plasmodium ovale were 8.6% (95% CI 7.6–9.7) and 3.1% (95% CI 2.5–3.8), respectively. For P. falciparum seroprevalence estimates were significantly higher at lower elevations (

Grignard L, Shah S, Chua T, et al.

AbstractTo determine the presence and species composition of malaria infections, we screened a subset of samples collected during a cross-sectional survey in Northern Sabah, Malaysia using highly sensitive molecular techniques. Results identified 54 asymptomatic submicroscopic malaria infections, including a large cluster of Plasmodium falciparum and three P. knowlesi infections. We additionally identified two mono-infections with the zoonotic malaria Plasmodiumcynomolgi, both in individuals reporting no history of forest activities or contact with macaques. Results highlight the need for improved surveillance strategies to detect these infections and determine public health impacts.

Francois H Nosten, Aung Pyae Phyo

In The Lancet, Katherine Battle1 and Daniel Weiss2 and colleagues present new malaria maps. These maps are the result of a considerable effort and will undoubtedly be well received by individuals interested in malaria. Several novelties and improvements from earlier versions are noticeable: the data for Plasmodium falciparum now cover the entire endemic world and include 5 km × 5 km pixel-level maps of mortality. Importantly, these are the first dynamic maps on Plasmodium vivax and for both plasmodial species; they include a time series spanning from 2000 to 2017.

Su, X.-z., Lane, K. D., Xia, L., Sa, J. M., Wellems, T. E.

Protozoan Plasmodium parasites are the causative agents of malaria, a deadly disease that continues to afflict hundreds of millions of people every year. Infections with malaria parasites can be asymptomatic, with mild or severe symptoms, or fatal, depending on many factors such as parasite virulence and host immune status. Malaria can be treated with various drugs, with artemisinin-based combination therapies (ACTs) being the first-line choice. Recent advances in genetics and genomics of malaria parasites have contributed greatly to our understanding of parasite population dynamics, transmission, drug responses, and pathogenesis. However, knowledge gaps in parasite biology and host-parasite interactions still remain. Parasites resistant to multiple antimalarial drugs have emerged, while advanced clinical trials have shown partial efficacy for one available vaccine. Here we discuss genetic and genomic studies of Plasmodium biology, host-parasite interactions, population structures, mosquito infectivity, antigenic variation, and targets for treatment and immunization. Knowledge from these studies will advance our understanding of malaria pathogenesis, epidemiology, and evolution and will support work to discover and develop new medicines and vaccines.…

Abstract Background The importance of submicroscopic malaria infections in high-transmission areas could contribute to maintain the parasite cycle. Regarding non-endemic areas, its importance remains barely understood because parasitaemia in these afebrile patients is usually below the detection limits for microscopy, hence molecular techniques are often needed for its diagnosis. In addition to this, the lack of standardized protocols for the screening of submicroscopic malaria in immigrants from endemic areas may underestimate the infection with Plasmodium spp. The aim of this study was to assess the prevalence of submicroscopic malaria in afebrile immigrants living in a non-endemic area. Methods A prospective, observational, multicentre study was conducted. Afebrile immigrants were included, microscopic observation of Giemsa-stained thin and thick blood smears, and two different molecular techniques detecting Plasmodium spp. were performed. Patients with submicroscopic malaria were defined as patients with negative blood smears and detection of DNA of Plasmodium spp. with one or both molecular techniques. Demographic, clinical, analytical and microbiological features were recorded and univariate analysis by subgroups was carried out with STATA v15. Results A total of 244 afebrile immigrants were included in the study. Of them, 14 had a submicroscopic malaria infection, yielding a prevalence of 5.7% (95% confidence interval 3.45–9.40). In 71.4% of the positive PCR/negative microscopy cases, Plasmodium falciparum alone was the main detected species (10 out of the 14 patients) and in 4 cases (28.6%) Plasmodium vivax or Plasmodium ovale were detected. One patient had a mixed infection including three different species. Conclusions The prevalence of submicroscopic malaria in afebrile immigrants was similar to that previously described in Spain. Plasmodium vivax and P. ovale were detected in almost a third of the submicroscopic infections. Screening protocols for afebrile immigrants with molecular techniques could be useful for a proper management of these patients.…

Abstract Background Large-scale surveillance of molecular markers of anti-malarial drug resistance is an attractive method of resistance monitoring, to complement therapeutic efficacy studies in settings where the latter are logistically challenging. Methods Between 2014 and 2017, this study sampled malaria rapid diagnostic tests (RDTs), used in routine clinical care, from two health centres in Bissau, Guinea-Bissau. In order to obtain epidemiological insights, RDTs were collected together with patient data on age and sex. A subset of positive RDTs from one of the two sites (n = 2184) were tested for Plasmodium DNA content. Those testing positive for Plasmodium DNA by PCR (n = 1390) were used for library preparation, custom designed dual indexing and next generation Miseq targeted sequencing of Plasmodium falciparum genes pfcrt, pfmdr1, pfdhfr, pfdhps and pfk13. Results The study found a high frequency of the pfmdr1 codon 86N at 88–97%, a significant decrease of the pfcrt wildtype CVMNK haplotype and elevated levels of the pfdhfr/pfdhps quadruple mutant ranging from 33 to 51% between 2014 and 2017. No polymorphisms indicating artemisinin tolerance were discovered. The demographic data indicate a large proportion of young adults (66%, interquartile range 11–28 years) presenting with P. falciparum infections. While a total of 5532 gene fragments were successfully analysed on a single Illumina Miseq flow cell, PCR-positivity from the library preparation varied considerably from 13 to 87% for different amplicons. Furthermore, pre-screening of samples for Plasmodium DNA content proved necessary prior to library preparation. Conclusions This study serves as a proof of concept for using leftover clinical material (used RDTs) for large-scale molecular surveillance, encompassing the inherent complications regarding to methodology and analysis when doing so. Factors such as RDT storage prior to DNA extraction and parasitaemia of the infection are likely to have an effect on whether or not parasite DNA can be successfully analysed, and are considered part of the reason the data yield is suboptimal. However, given the necessity of molecular surveillance of anti-malarial resistance in settings where poor infrastructure, poor economy, lack of educated staff and even surges of political instability remain major obstacles to performing clinical studies, obtaining the necessary data from used RDTs, despite suboptimal output, becomes a feasible, affordable and hence a justifiable method.…

Leang, R., Khim, N., Chea, H., Huy, R., Mairet-Khedim, M., Mey Bouth, D., Dorina Bustos, M., Ringwald, P., Witkowski, B.

This single-arm trial (N=104) in western Cambodia, showed high efficacy for 3-day pyronaridine-artesunate plus single-dose primaquine in Plasmodium falciparum malaria: day-42 PCR-adjusted adequate clinical and parasitological response (ACPR) was 98.3% ([58/59] 95%CI 90.9–100.0) in Trapeng Chau (Kampong Speu), and 100% ([41/41] 95%CI 91.4–100) in Veal Veng (Pursat); 80.6% (83/103) had drug resistance molecular markers. For P. vivax, pyronaridine-artesunate day-28 ACPR was 98.3% (59/60; 95%CI 91.1–100) and 100% (60/60; 95%CI 94.0–100), respectively.…

Hannah Koenker, Cameron Taylor, Clara R. Burgert-Brucker, Julie Thwing, Tom Fish and Albert Kilian

Abstract. Seasonal variation in the proportion of the population using an insecticide-treated net (ITN) is well documented and is widely believed to be dependent on mosquito abundance and heat, driven by rainfall and temperature. However, seasonal variation in ITN use has not been quantified controlling for ITN access. Demographic and Health Survey and Malaria Indicator Survey datasets, their georeferenced data, and public rainfall and climate layers were pooled for 21 countries. Nine rainfall typologies were developed from rainfall patterns in Köppen climate zones. For each typology, the odds of ITN use among individuals with access to an ITN within their households (“ITN use given access”) were estimated for each month of the year, controlling for region, wealth quintile, residence, year, temperature, and malaria parasitemia level. Seasonality of ITN use given access was observed over all nine rainfall typologies and was most pronounced in arid climates and less pronounced where rainfall was relatively constant throughout the year. Peak ITN use occurred 1–3 months after peak rainfall and corresponded with peak malaria incidence and average malaria transmission season. The observed lags between peak rainfall and peak ITN use given access suggest that net use is triggered by mosquito density. In equatorial areas, ITN use is likely to be high year-round, given the presence of mosquitoes and an associated year-round perceived malaria risk. These results can be used to inform behavior change interventions to improve ITN use in specific times of the year and to inform geospatial models of the impact of ITNs on transmission.…

Abstract Background Malaria preventive measures, including long-lasting insecticide-treated bet nets (LLINs), indoor residual spraying (IRS), and controlling mosquito breeding sites, are key measures to achieve malaria elimination. Still, compliance with these recommended measures remains a major challenge. By applying a novel and comprehensive model for determinants of malaria prevention behaviour, this study tests how individual perceptions influence the intentions to use malaria preventive measures and explores strategies that stimulate their consistent use. Methods The study was carried out in the sectors of Ruhuha and Busoro, Rwanda during October and November 2017, and these were conducted into two phases. Phase one involved a questionnaire survey (N = 742), whereas Phase two employed a qualitative approach that included nine focus group discussions, seven key informant interviews, and three in-depth interviews. Results The findings of the quantitative study showed that participants very often use LLINs (66.6%), accept IRS (73.9%), and drain stagnant water in case of presence (62%). The intentions to use malaria preventive measures were consistently driven by perceived severity, perceived self-efficacy, perceived response efficacy, and subjective norms, and hindered by perceived barriers. The intentions were also positively associated with the actual use of LLINs, acceptance of IRS, and drainage of stagnant water. There is no evidence that either not having enough LLINs (ownership of at least one bed net in the household, here referred to as availability) or having sufficient LLINs (having one LLIN per two people in the household, here referred to as accessibility) moderated the relationship between behavioural intentions and actual use of LLINs. The qualitative study indicated that participants believed malaria risk to be high and perceived a high mosquito density. They also believed that repetitive malaria episodes are caused by the perceived low effectiveness of anti-malaria medications. Lack of LLINs increased the perceived added value of LLINs, and together with the increased malaria burden increased the perceived response efficacy. Participants highlighted the need to continuously mobilize and engage community members especially those who do not use LLINs when having one, and those who do not accept the spraying activities. Conclusion Malaria prevention interventions should target individual perceptions to enhance consistent use of malaria preventive measures. Three strategies to improve consistent use and acceptance of these measures are highlighted: (1) ensure access to LLINs and regular spraying activities, (2) community mobilization and (3) citizen engagement in malaria prevention activities.…