Endemic Malaria Research Articles

Rapid Diagnostic Test (HRP2/pLDH) Positivity, Household Malaria Incidence and Impact of Community Participatory WASH Action in Kongo Central, DR Congo: A Mixed Method Study

Summary: Malaria is one of the most prevalent and deadliest illnesses in the Sub-Saharan Africa. Despite recent gains made towards its control or elimination in past decades, many African countries still have endemic malaria transmission. Therefore, the search for novel disease control strategies and approaches are in progress. This study aimed to evaluate household malaria burden in Kongo central province, Democratic Republic of Congo (DRC), and the impact of community participatory water, sanitation and hygiene (WASH) action. Methods: Mixed method study was conducted in two semi-rural towns, Mbanza-Ngungu (WASH action site) and Kasangulu (control site), involving 625 households (3,712 individuals). Baseline and post-intervention surveys were conducted; an action research consisting of six-month prospective study was carried out which comprised two interventions: (1) community participatory WASH action and (2) anti-malaria education campaign. The latter was implemented in both study sites. In addition, rapid diagnostic test (RDT) for malaria was performed in respondents. Findings: Prevalence of positive malaria RDT among respondents decreased (38% vs. 20%) at WASH-action site, whereas it increased at the control site but not significantly. Of 96% of respondents who reported at least one malaria event occurring in the previous six-month period, only 66.5% of them received malaria care at a health setting. At household level, long-lasting insecticide-treated net (LLIN) was the most commonly used preventive measure (55%), followed by mosquito repellent (15%), indoor residual spraying (IRS) (2%), LLIN-IRS combination (2%); however, 24% of households did not use any measures. Mean household malaria incidence decreased in WASH action site; 2.3±2.2 cases vs. 1.2±0.7 cases, whereas no significant change was noted in control site. Moreover, malaria incidence rate was highest (60.9%) among households living in proximity to grassy and stagnant water spots. Proximity to high risk area (grassy/stagnant water spots) for malaria (ORa=5.13; 95%CI: 2-29-8.07; p<0.001), poor WASH (ORa=4.10; 95%CI: 2.11-7.08; p<0.001), and low household income (ORa=2.37; 95%CI: 1.05-3.12; p<0.05) were determinants of household malaria. Interpretation: Findings suggest the necessity to scale up the fight against malaria by integrating efficient indoor and outdoor preventive measures, including WASH intervention in residential environment, and improve malaria care accessibility. Funding Statement: This work was supported in part by JSPS KAKENHI Grant Number JP 17H04675. Declaration of Interests: The authors have no conflict of interest related to this study. Ethics Approval Statement: Prior to implementing this research, informed consent from was obtained from each household head, and ethical approval was also obtained from the School of Public Health of the University of Lubumbashi and the Faculty of Medicine of William Booth University in DRC. All medical procedures performed in this study were in accordance with the Helsinki declaration regarding the use of human subjects in research.

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age.

Home fortification of foods with multiple micronutrient powders for health and nutrition in children under two years of age.

Effectiveness and safety of intermittent preventive treatment for malaria using either dihydroartemisinin-piperaquine or artesunate-amodiaquine in reducing malaria related morbidities and improving cognitive ability in school-aged children in Tanzania: A study protocol for a controlled randomised trial

BackgroundIn high transmission settings, up to 70% of school-aged children harbour malaria parasites without showing any clinical symptoms. Thus, epidemiologically, school aged children act as a substantial reservoir for malaria transmission. Asymptomatic Plasmodium infections induce inflammation leading to iron deficiency anaemia. Consequently, anaemia retards child growth, predisposes children to other diseases and reduces cognitive potential that could lead to poor academic performance. School aged children become increasingly more vulnerable as compared to those aged less than five years due to delayed acquisition of protective immunity. None of the existing Intermittent Preventive Treatment (IPT) strategies is targeting school-aged children. Here, we describe the study protocol of a clinical trial conducted in north-eastern Tanzania to expand the IPT by assessing the effectiveness and safety of two antimalarial drugs, Dihydroartemisinin-Piperaquine (DP) and Artesunate-Amodiaquine (ASAQ) in preventing malaria related morbidities in school-aged children (IPTsc) living in a high endemic area. Methods/designThe trial is a phase IIIb, individual randomized, open label, controlled trial enrolling school children aged 5–15 years, who receive either DP or ASAQ or control (no drug), using a “balanced block design” with the “standard of care” arm as reference. The interventional treatments are given three times a year for the first year. A second non-interventional year will assess possible rebound effects. Sample size was estimated to 1602 school children (534 per group) from selected primary schools in an area with high malaria endemicity. Thick and thin blood smears (to measure malaria parasitaemia using microscope) were obtained prior to treatment at baseline, and will be obtained again at month 12 and 20 from all participants. Haemoglobin concentration using a haemoglobinometer (HemoCue AB, Sweden) will be measured four monthly. Finger-prick blood (dried bloodspot-DBS) prepared on Whatman 3 M filter paper, will be used for sub-microscopic malaria parasite detection usingPCR, detect markers of drug resistance (using next generation sequencing (NGS) technology), and malaria serological assays (using enzyme-linked immunosorbent assay, ELISA). To determine the benefit of IPTsc on cognitive and psychomotor ability test of everyday attention for children (TEA-Ch) and a ‘20 m Shuttle run’ respectively, will be conducted at baseline, month 12 and 20. The primary endpoints are change in mean haemoglobin from baseline concentration and reduction in clinical malaria incidence at month 12 and 20 of follow up. Mixed design methods are used to assess the acceptability, cost-effectiveness and feasibility of IPTsc as part of a more comprehensive school children health package. Statistical analysis will be in the form of multilevel modelling, owing to repeated measurements and clustering effect of participants. DiscussionMalaria intervention using IPTsc strategy may be integrated in the existing national school health programme. However, there is limited systematic evidence to assess the effectiveness and operational feasibility of this approach. School-aged children are easily accessible in most endemic malaria settings. The evidence from this study will guide the implementation of the strategy to provide complementary approach to reduce malaria related morbidity, anaemia and contribute to the overall burden reduction. Trial registrationClinicaltrials.gov: NCT03640403, registered on Aug 21, 2018, prospectively registered.Url https://www.clinicaltrials.gov/ct2/show/NCT03640403?term=NCT03640403&rank=1.

Malaria Antigen Shedding in the Breast Milk of Mothers From a Region With Endemic Malaria

This study examines the association of malaria exposure to malaria antigen in breast milk among lactating women with asymptomatic malaria.

Discovery of Malaria Cases on Forest Workers In Public Health Center, Teluk Kepayang, Tanah Bumbu, South Kalimantan

Regency of Tanah Bumbu has an annual parasitic incidence rate (API) 0.82 and in 2016 the number of API decreased to 0.48. However, there are malaria cases that still occur in the 5 (five) locations of the workplace of the public health center with the category High Case Incidence (HCI). Determining factors in the case of malaria in Tanah Bumbu district are malaria parasites (Plasmodium falciparum, P. vivax, and mixed), and forest workers. The more dominant malaria attacked the population in the working area of the public health center is the malaria vivax and the mix (P. falciparum and P. vivax). The purpose of the study was to determine the dominant Plasmodium species that attacked the population. The type of descriptive research with cross-sectional design in the village endemic malaria of the HCI category in the working area of the public health center in the district of Tanah Bumbu. The results show that a total of 773 respondents was examined to detect cases of malaria, mixed malaria results (P. falciparum and P. vivax), and P. vivax were dominantly found in adult men who worked as a forest protector and miners in 73% of cases. While in adult women are gardening in the find 27% of cases of malaria species (P. falciparum and P. vivax) and P. vivax. Conclusion: The rides of malaria sufferers in the working area of the public health center with a total value of SPR 1%. Thus, for people in the working area of the public health center to use a mosquito net with insecticide during the special night, and use mosquito repellent to avoid mosquito bites and use prophylactic drugs when going to the fields/ Forests for work.

Evaluation of the Sensitivity of Rapid Diagnostic Test (RDT) of Malaria in Different Age and Sex Groups Using Microscopy as a Gold Standard

Malaria remains a public health problem in over 90 countries worldwide, especially in Africa where it is the cause of morbidity and mortality. The aim of the study is to compare the sensitivity of two rapid diagnostic test kits in the diagnosis of malaria among patients attending Yobe State Specialist Hospital Damaturu. Patients were screened for malaria using blood samples collected in an EDTA container. Patients were tested with one Histidine rich protein-2(HRP-2) RDT (SD-Bioline) and a combination of Histidine rich protein-2(HRP-2) and Parasite lactose dehydrogenase enzyme (pLDH) RDT (CareStart). Microscopy was used as a gold standard. Out of 200 participants enrolled and screened for malaria, 200 (100%) tested positive by Microscopy, 159 (79.5%), tested positive by SD-Bioline (HRP 2 RDT) while 139 (69.5%), tested positive with the CareStart (pLDH RDT). Upon detection of the sensitivity by serially diluting the positive samples in other to decrease the parasite density; SD-Bioline was reactive at 1:4 dilution while CareStart was weekly reactive at this dilution. Although SD-Bioline showed to have a higher sensitivity than CareStart, both could be a suitable alternative to microscopy to screen endemic malaria in Nigeria.

Modeling the Dynamics of Endemic Malaria Transmission with the Effects of Control Measure

Malaria is an infectious disease caused by Plasmodium parasite and is transmitted among humans through bites of female Anopheles mosquitoes. It is estimated 216 million people suffered from malaria in 2016, with over 400,000 deaths mainly in sub-Saharan Africa. A number of control measures have been put in place: most importantly the insecticide treated net (ITN) and indoor residual sprayings (IRS) of insecticide. Currently, the emergence and spread of resistance in mosquito populations against insecticides is the most common and widely spread .It is also poses a key obstacle to malaria control as well as jeopardizing the effects of the most efficient malaria control interventions. A mathematical model that incorporates the evolution of insecticide resistance and its impact on endemic malaria transmission i.e., effects of indoor residual sprayings (IRS) on the insecticide resistant and sensitive malaria vector strains as a control strategy is incorporated and analyzed. The object of the study is to understand qualitatively the factor that have more influence for the emergence and spread of resistance of malaria vectors against IRS and their impacts on the efficacy of IRS. Based on a Ross-Macdonald derivation of malaria model the effective reproduction number〖 R〗_e isused to assess the effects of IRS in the qualitative analysis of the model. The existence and stability of the disease-free and endemic equilibria of the model are studied. It is established that the malaria can be brought under control as long as R_(e )is kept below the threshold value. Numerical simulations studies are conducted so as to determine the role played by key parameters of the model. The public health implications of the results include: (i) every effort should be taken to minimize the evolution of insecticide resistance due to malaria control interventions failure and (ii) at least a combination of two types of different control measures and followed by rotation of intervention strategies could be more realistic to minimize the number of resistant malaria vector strains and essential in reducing the malaria burden in the community.

Species composition, geographical distribution and seasonal abundance of the Anopheles maculipennis complex along the Upper Rhine, Germany.

Between May and September 2016, mosquitoes were collected on a biweekly basis at 55 locations with CO2-baited encephalitis vector surveillance traps along the Upper Rhine, Germany, to evaluate the species composition, geographical distribution and abundance of the Anopheles maculipennis complex, some members of this complex being considered vectors of historical malaria in Germany. A total of 2115 Anopheles maculipennis complex specimens were collected during the season, of which a sample of 1252 individuals was determined to species level by amplification of species-specific internal transcribed spacer 2 (ITS2) sequences. A total of 856 individuals of Anopheles daciae (68.37%), 394 Anopheles messeae (31.47%) and 2 Anopheles maculipennis s.s. (0.16%) were recorded. The number and proportion of A. daciae was remarkably higher in the northern meandering zone of the Upper Rhine (843 specimens, 79.90%), than in the more canalised southern furcation zone where A. messeae with 183 collected specimens represented 92.89% of 197 classified individuals. The average number of collected A. maculipennis s.l. individuals per trapping site was 38.45, equalling 0.64% of the total mosquito collection. Despite an increase in imported malaria cases, this comparatively low abundance of A. maculipennis s.l. may indicate a low risk of endemic malaria transmission by members of the A. maculipennis complex today. The proportionally dominance of A. daciae suggests that this species could be suspected the main historical vector of malaria in the Upper Rhine region. Sequence analyses of the ITS2 fragment revealed intraindividual polymorphisms within 3 of 5 diagnostic nucleotides in all specimens of A. daciae, raising the question if additional loci should be considered, to gain further insight into the taxonomical relation to A. messeae.

Vector dynamics predicts transmission dynamics: a simple, realistic and sensible approach for measuring malaria endemicity.

Entomological indicators such as vector density, distribution, biology and bionomics and their vectorial attributes are important parameters for measuring the pattern and intensity of malaria transmission. Although published articles provide evidence for the existence of associations between entomological indices and malaria transmission dynamics, none of them is able to establish a strong correlation. In order to address this issue, the present study aims to assess how malaria transmission is influenced and can be predicted by local major vector dynamics. We carried out an entomological assessment of major Anopheline vector abundance, habit/habitat, resting and feeding behavior, infectivity rates, and other entomological parameters. Results suggest that malaria transmission was correlated with a vector control intervention and non-intervention scenario in a high endemic region of Kalahandi district of Odisha, India. Amongst all indices, infective anthropophagic vectors established a strong positive correlation with malaria morbidity in comparison to infective or anthropophagic vector species during both the study periods. Though other entomological parameters influenced the transmission intensity, little quantifiable association was detected among study sites. This study provides strong baseline evidence of an association between entomological indices and malaria transmission dynamics, which could be used as an early warning system for outbreak prediction.

Guidance for Using Tafenoquine for Prevention and Antirelapse Therapy for Malaria - United States, 2019.

An estimated 219 million cases of malaria occurred worldwide in 2017, causing approximately 435,000 deaths (1). Malaria is caused by intraerythrocytic protozoa of the genus Plasmodium transmitted to humans through the bite of an infective Anopheles mosquito. Five Plasmodium species that regularly cause illness in humans are P. falciparum, P. vivax, P. ovale, P. malariae, and P. knowlesi (2). The parasite first develops in the liver before infecting red blood cells. Travelers to areas with endemic malaria can prevent malaria by taking chemoprophylaxis. However, most antimalarials do not kill the liver stages of the parasite, including hypnozoites that cause relapses of disease caused by P. vivax or P. ovale. Therefore, patients with these relapsing species must be treated with two medications: one for the acute infection, and another to treat the hypnozoites (antirelapse therapy). Until recently, primaquine was the only drug available worldwide to kill hypnozoites. Tafenoquine, a long-acting 8-aminoquinoline drug related to primaquine, was approved by the Food and Drug Administration (FDA) on July 20, 2018, for antirelapse therapy (Krintafel) and August 8, 2018, for chemoprophylaxis (Arakoda) (3,4). This report reviews evidence for the efficacy and safety of tafenoquine and provides CDC guidance for clinicians who prescribe chemoprophylaxis for travelers to areas with endemic malaria and treat malaria.

Cultivating China's Cinchona: The Local Developmental State, Global Botanic Networks and Cinchona Cultivation in Yunnan, 1930s-1940s.

SummaryThis article reconstructs the history of China’s first successful cinchona cultivation programme in Hekou, Yunnan province from the 1930s to 1940s during the Nationalist era (1928–49). I argue that the Hekou programme was initiated by the Yunnan ‘local developmental state’ to control endemic malaria and achieve quinine self-sufficiency. It was expanded during the Sino-Japanese War (1937–45) as part of the national defence project in order to develop Yunnan’s malaria-ridden southwest frontier to provide more resources for the war, as well as to solve broader wartime epidemic crises in southwest China. A closer examination also indicates that the development of the Hekou programme was closely intertwined with global networks of cinchona cultivation and international politics.

Immune Responses to Gametocyte Antigens in a Malaria Endemic Population-The African falciparum Context: A Systematic Review and Meta-Analysis.

Background: Malaria elimination remains a priority research agenda with the need for interventions that reduce and/or block malaria transmission from humans to mosquitoes. Transmission-blocking vaccines (TBVs) are in development, most of which target the transmission stage (i.e., gametocyte) antigens Pfs230 and Pfs48/45. For these interventions to be implemented, there is a need to understand the naturally acquired immunity to gametocytes. Several studies have measured the prevalence of immune responses to Pfs230 and Pfs48/45 in populations in malaria-endemic areas.Methods: We conducted a systematic review of studies carried out in African populations that measured the prevalence of immune responses to the gametocyte antigens Pfs230 and Pfs48/45. We assessed seroprevalence of antibody responses to the two antigens and investigated the effects of covariates such as age, transmission intensity/endemicity, season, and parasite prevalence on the prevalence of these antibody responses by meta-regression.Results: We identified 12 studies covering 23 sites for inclusion in the analysis. We found that the range of reported seroprevalence to Pfs230 and Pfs48/45 varied widely across studies, from 0 to 64% for Pfs48/45 and from 6 to 72% for Pfs230. We also found a modest association between increased age and increased seroprevalence to Pfs230: adults were associated with higher seroprevalence estimates in comparison to children (β coefficient 0.21, 95% CI: 0.05–0.38, p = 0.042). Methodological factors were the most significant contributors to heterogeneity between studies which prevented calculation of pooled prevalence estimates.Conclusions: Naturally acquired sexual stage immunity, as detected by antibodies to Pfs230 and Pfs48/45, was present in most studies analyzed. Significant between-study heterogeneity was seen, and methodological factors were a major contributor to this, and prevented further analysis of epidemiological and biological factors. This demonstrates a need for standardized protocols for conducting and reporting seroepidemiological analyses.

Early-life Exposure to Malaria Eradication and Later-life Cognition: Evidence from India

This paper examines the effects of early-life malaria exposure on later-life cognition in a sample of Indian mid-aged and older adults, using a nationwide eradication program and geographic variation in pre-eradication malaria endemicity. Difference-in-difference estimates suggest that the program was associated with an increase of 0.3 standard deviation in a measure of episodic memory for both men and women, and a similar increase in a measure of retrieval/fluency for women. No positive treatment effects were found for the cognitive domain of attention and working memory.

Role of malaria control in improving child health in mainland Tanzania: Evidence from a rapid policy scale-up

Abstract Malaria control is a major policy concern in Sub-Saharan Africa, where the disease imposes a high burden on child health. Between 2004 and 2010, in mainland Tanzania, malaria control interventions have experienced a rapid scale-up evidenced by a sharp increase of the budget devoted to malaria control, rising from less than $10 million to nearly $140 million. However, the extent to which these interventions have improved child health remains an open policy question. I exploit the timing of the fast scale-up of the malaria control program, along with the variation in malaria endemicity across the country due to climate, to evaluate the impact of malaria control interventions on child health with a difference-in-difference approach. My estimates suggest that, on average, malaria control interventions have helped avert approximately 17.9 deaths for every 1000 live births. In relative terms, they have contributed to 57.7 percent of the reduction in under-five mortality between 2004 and 2010. These interventions have also improved other measures of child health, such as anemia and stunting, reducing the odds of these conditions by 52 and 35 percent, respectively. Calculations suggest that it costs at most 4100 US dollars to save a child through the program. Finally, the malaria control program passes the test of a positive net present value with a value of a statistical life as low as 4600 US dollars for discount rates ranging from 10 to 20 percent.

A geographical study of the risk factors of a differentiated transmission of malaria in two districts of Bouaké (Ivory Coast)

Malaria is a parasitic vector disease whose transmission is linked to a combination of multiple factors related to the vector, the parasite, the human host and its environment. In addition to the high prevalence in the tropical zone, the endemic malaria area, there are significant disparities in the transmission of the disease between rural and urban areas, where the highest prevalence of malaria is observed, but also within the cities themselves. While the city, which appears to be unfavoura...

Transition from endemic behavior to eradication of malaria due to combined drug therapies: An agent-model approach

We introduce an agent-based model describing a susceptible-infectious-susceptible (SIS) system of humans and mosquitoes to predict malaria epidemiological scenarios in realistic biological conditions. Emphasis is given to the transition from endemic behavior to eradication of malaria transmission induced by combined drug therapies acting on both the gametocytemia reduction and on the selective mosquito mortality during parasite development in the mosquito. Our mathematical framework enables to uncover the critical values of the parameters characterizing the effect of each drug therapy. Moreover, our results provide quantitative evidence of what was up to now only partially assumed with empirical support: interventions combining gametocytemia reduction through the use of gametocidal drugs, with the selective action of ivermectin during parasite development in the mosquito, may actively promote disease eradication in the long run. In the agent model, the main properties of human-mosquito interactions are implemented as parameters and the model is validated by comparing simulations with real data of malaria incidence collected in the endemic malaria region of Chimoio in Mozambique. Finally, we discuss our findings in light of current drug administration strategies for malaria prevention, which may interfere with human-to-mosquito transmission process.

Knowledge, attitude and practice towards malaria among symptomatic patients attending Tumbi Referral Hospital: A cross-sectional study.

BackgroundDespite significant improvement in prevention and control over the past decades malaria remains a significant public health concern in Tanzania with 93% of the population being at risk. To prevent malaria infection and promote malaria free zones, understanding the community’s knowledge, attitudes, and practices toward malaria control are essential. This study therefore aimed at determining the levels of understanding, and attitudes, as well as socio-cultural aspects of malaria prevention and treatment-seeking behaviours among suspected malaria patients.MethodsThis study was a hospital based cross-sectional study, in which patients attending Tumbi Referral Hospital with symptoms and signs that warrant inclusion of suspicion of malaria, were recruited. We used a pre-tested semi-structured questionnaire to collect participants’ demographic characteristics, as well as information on their knowledge, attitudes, and practices towards malaria infection. Data were analysed using Stata Version 12.1.ResultsWe enrolled a total of 295 respondents of which 179 (60.68%) were females. Participants’ ages ranged from 1–91 years, with a mean of 31.4 years. Seventy-nine (26.8%) patients reported having malaria in the previous 28 days, with 57 (72.2%) being laboratory confirmed. Only 52 (65.8%) individuals reported taking prescribed medications for malaria. A total of 277 (93.90%) were aware of malaria, and 264 (95.31%) knew that it is transmitted by mosquito. Nearly all participants (263, 94.95%), identified sleeping under bed nets to be protective against malaria. About half of the respondents either agreed 63 (22.74%) or strongly agreed 62 (22.38%) that malaria can be transmitted like the common cold. Self-reported mosquito net use was 88.09% (244).ConclusionDespite the endemicity of malaria in our study site, patients had adequate knowledge, encouraging attitudes, and good practices related to malaria prevention and control.

Filthy Flourishing

Thousands of marabou storks occupy Kampala, nesting in the city’s green spaces and eating up to 2 kilos of organic matter daily, mostly rotting garbage found in the city’s open dumps. Weedy birds, they flourish amid Kampala’s garbage crisis. Storks are both waste infrastructure and waste themselves, rendered disposable by the same state-centric views of infrastructure that make informal waste pickers precarious, and cast out from the imaginary of a clean, green, urban future. Theorizing animal and informal infrastructures together as “para-sites,” this paper follows marabou storks through Kampala’s ever-shifting waste frontier: the postconsumer equivalent to the extractive frontier that subtends the capitalist fantasy of endless growth. Kampala’s topography, hydrology, and class structure ensure that trash flows downhill, accumulating in slums where it leads to flooding and outbreaks of cholera, typhoid, and other waterborne illnesses as well as to endemic malaria. Waste with wings, marabou storks remake the urban waste landscape, undermining efforts to stabilize the city’s ultimate sinks in landfills, slums, and wetlands as they flourish in filth and defecate in the heart of greenness.

8-Aminoquinoline Therapy for Latent Malaria.

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.

Measuring malaria morbidity in an area of seasonal transmission: Pyrogenic parasitemia thresholds based on a 20-year follow-up study.

IntroductionAsymptomatic carriage of P. falciparum is frequent in areas endemic for malaria and individual diagnosis of clinical malaria attacks is still difficult. We investigated the impact of changes in malaria endemicity on the diagnostic criteria for malaria attacks in an area of seasonal malaria transmission.MethodsWe analyzed the longitudinal data collected over 20 years from a daily survey of all inhabitants of Ndiop, a rural community in central Senegal, in a logistic regression model to investigate the relationship between the level of Plasmodium falciparum parasitemia and the risk of fever, with the aim of determining the best parasitemia thresholds for attributing to malaria a fever episode.ResultsA total of 34,136 observations recorded from July 1993 to December 2013 from 850 individuals aged from 1 day to 87 years were included. P. falciparum asymptomatic carriage declined from 36% to 1% between 1993 and 2013. A total of 9,819 fever episodes were associated with a positive blood film for P. falciparum. Using age-dependent parasitemia thresholds for attributing to malaria a fever episode, we recorded 6,006 malaria attacks during the study period. Parasitemia thresholds seemed to be lower during the low-to-zero transmission season and tended to decrease with changes in control policies. The number of clinical malaria attacks was overestimated for all age groups throughout the study when all fever episodes associated with P. falciparum parasitemia were defined as malaria attacks.ConclusionPyrogenic thresholds are particularly sensitive to changes in malaria epidemiology and are therefore an interesting tool to accurately assess the burden of malaria in the context of declining transmission.