Search

Background Many studies report associations between human genetic factors and immunity to malaria but few have been reliably replicated. These studies are usually country-specific, use small sample sizes and are not directly comparable due to differences in methodologies. This study brings together samples and data collected from multiple sites across Africa and Asia to use standardized methods to look for consistent genetic effects on anti-malarial antibody levels. Methods Sera, DNA samples and clinical data were collected from 13,299 individuals from ten sites in Senegal, Mali, Burkina Faso, Sudan, Kenya, Tanzania, and Sri Lanka using standardized methods. DNA was extracted and typed for 202 Single Nucleotide Polymorphisms with known associations to malaria or antibody production, and antibody levels to four clinical grade malarial antigens [AMA1, MSP1, MSP2, and (NANP)4] plus total IgE were measured by ELISA techniques. Regression models were used to investigate the associations of clinical and genetic factors with antibody levels. Results Malaria infection increased levels of antibodies to malaria antigens and, as expected, stable predictors of anti-malarial antibody levels included age, seasonality, location, and ethnicity. Correlations between antibodies to blood-stage antigens AMA1, MSP1 and MSP2 were higher between themselves than with antibodies to the (NANP)4 epitope of the pre-erythrocytic circumsporozoite protein, while there was little or no correlation with total IgE levels. Individuals with sickle cell trait had significantly lower antibody levels to all blood-stage antigens, and recessive homozygotes for CD36 (rs321198) had significantly lower anti-malarial antibody levels to MSP2. Conclusion Although the most significant finding with a consistent effect across sites was for sickle cell trait, its effect is likely to be via reducing a microscopically positive parasitaemia rather than directly on antibody levels. However, this study does demonstrate a framework for the feasibility of combining data from sites with heterogeneous malaria transmission levels across Africa and Asia with which to explore genetic effects on anti-malarial immunity. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0833-x) contains supplementary material, which is available to authorized users.

Artemisinin resistant Plasmodium falciparum is advancing across Southeast Asia in a soft selective sweep involving at least 20 independent kelch13 mutations. In a large global survey, we find that kelch13 mutations which cause resistance in Southeast Asia are present at low frequency in Africa. We show that African kelch13 mutations have originated locally, and that kelch13 shows a normal variation pattern relative to other genes in Africa, whereas in Southeast Asia there is a great excess of non‐synonymous mutations, many of which cause radical amino‐acid changes. Thus, kelch13 is not currently undergoing strong selection in Africa, despite a deep reservoir of standing variation that could potentially allow resistance to emerge rapidly. The practical implications are that public health surveillance for artemisinin resistance should not rely on kelch13 data alone, and interventions to prevent resistance must account for local evolutionary conditions, shown by genomic epidemiology to differ greatly between geographical regions.

Market-oriented production of gardening crops and cassava (Manihot utilissima) in the dry season is an increasingly frequent practice in Segou, Mali. Traditionally, these crops are protected from roaming livestock with the help of dead fences. In order to provide a sustainable alternative to dead fences, the International Centre for Research in Agroforestry (ICRAF) began promoting the use of live fences, living trees planted closely together around a field plot. This study was conducted with the first farmers to use these live fences. These farmers expressed satisfaction with the protection offered by the trees and their ability to provide a variety of medicinal, economic, and food products. The form of land tenure, the social status of farmers within their families, and the availability of labour seem to be important factors in the decision to test the live fence. This raises questions about the accessibility of this technique and its possible contribution to the social and economic differentiation of its users.

IntroductionThere are growing concerns about the emergence of resistance to artemisinin-based combination therapies (ACTs). Since the widespread adoption of ACTs, there has been a decrease in the systematic surveillance of antimalarial drug resistance in many malaria-endemic countries. The aim of this work was to test whether data on travellers returning from Africa with malaria could serve as an additional surveillance system of local information sources for the emergence of drug resistance in endemic-countries.MethodologyData were collected from travellers with symptomatic Plasmodium falciparum malaria returning from Senegal (n = 1,993), Mali (n = 2,372), Cote d'Ivoire (n = 4,778) or Cameroon (n = 3,272) and recorded in the French Malaria Reference Centre during the period 1996-2011. Temporal trends of the proportion of parasite isolates that carried the mutant genotype, pfcrt 76T, a marker of resistance to chloroquine (CQ) and pfdhfr 108N, a marker of resistance to pyrimethamine, were compared for travellers and within-country surveys that were identified through a literature review in PubMed. The in vitro response to CQ was also compared between these two groups for parasites from Senegal.ResultsThe trends in the proportion of parasites that carried pfcrt 76T, and pfdhfr 108N, were compared for parasites from travellers and patients within-country using the slopes of the curves over time; no significant differences in the trends were found for any of the 4 countries. These results were supported by in vitro analysis of parasites from the field in Senegal and travellers returning to France, where the trends were also not significantly different.ConclusionThe results have not shown different trends in resistance between parasites derived from travellers or from parasites within-country. This work highlights the value of an international database of drug responses in travellers as an additional tool to assess the emergence of drug resistance in endemic areas where information is limited.

Background: pfcrt K76T mutation was demonstrated to play a central role in the P. falciparum resistance to chloroquine. Aim: To find any association between mutant alleles of pfcrt K76T, pfmdr1 N86Y, pfG30 and pfG47 and the in vivo parasite non clearance after chloroquine treatment in Mali. Methodology: We carried out a chloroquine efficacy study in 196 children suffering from uncomplicated malaria in a rural village of Kollé, Mali, using WHO protocol. Subjects were treated with standard dose of chloroquine and followed for 14 days. Parasite DNA was extracted from finger prick blood blotted onto filter paper and genotypes were analyzed by different PCR methods. Results: The mutant alleles pfcrt 76T and pfmdr1 86Y were associated with parasite non clearance with p=0.00001 and 0.03 respectively. However, the association of SNPs on pfG30 and pfG47 genes with parasite non clearance was not statistically significant, p =0.43 and 0.57 respectively. The logistic regression analysis showed that the mutant allele pfmdr186Y contributed positively to the pfcrt 76T parasites non clearance (p=0.02). Conclusion: These findings have shown that pfcrt76T and pfmdr1 86Y alleles are associated with the in vivo parasite non clearance, but not SNPs on the new putative transporters genes.

The aim of this study was to describe the malaria morbidity and the frequencies of molecular markers of resistance to chloroquine and sulfadoxine-pyrimethamine in pregnant women at delivery in Mali. Two hundred pregnant women have been included at the delivery clinic in Fana. The age group of 14-19 years was predominant. Fifty two per cent (52.3%: 104/200) were malaria slides positive in their peripheral blood and 15% (30/200) of the women carried parasite in their placenta. The prevalence rate of anemia was 44.5% (89/200). PCR technique was successfully performed on 16 paired samples. The frequency of the Pfcrt K76T mutants in Plasmodium falciparum infections in peripheral blood was 68.8% (11/16) and 100% (16/16) in the placenta (p = 0.004). The frequency in peripheral blood of the DHFR N51I mutation was 12.5% (2/16) and 18.8% (3/16) in the placenta (p=0.12). The frequencies of the DHPS A437G mutants were similar in both sites 25% (4/16). No DHPS K540E and DHFR 164L mutations were found in the Fana pregnancy women samples.

We recently reported that aminosterols are fungicidal due to their disrupting the outer membranes of yeasts and that they have a significant in vitro activity against various mould species. Yet, their activity against dermatophytes had never been tested. This study's objective was to evaluate the in vitro activity of squalamine and a synthetic aminosterol derivative (ASD) against various dermatophytes. Susceptibility testing of squalamine, ASD, terbinafine, and griseofulvin was performed, in triplicate, in accord with the Clinical Laboratory and Standards Institute's M38-A2 procedure, using an 80% growth inhibition endpoint. The studies included the following dermatophytes: Trichophyton rubrum, T. mentagrophytes, T. soudanense, Microsporum canis, M. audouinii, M. persicolor; M. cookie and M. gypseum. Squalamine and ASD showed significant in vitro activity against these dermatophytes. The minimum inhibitory concentrations (MICs) ranged from 4-16 mg/l and from 2-8 mg/l for squalamine and ASD, respectively. These findings support further clinical studies of aminosterols activity against superficial dermatophyte infections.

The epidemiology of the cutaneous leishmaniasis (CL) with Leishmania major is poorly documented in Mali. Following reports of CL in the tourist areas of the Dogon country (Bandiagara Escarpment), a joint French and Malian bio-clinical team conducted a field study from 16 to 27 January, 2010. The population of 5 villages has been examined by a dermato-infectiologist and cases were selected by visual inspection of skin lesions. Smears and biopsies (from the lesions) and venous blood were obtained from suspected cases of CL. Diagnosis was performed by light microscopy, in vitro cultures, serology and molecular biology. Fifty patients with skin lesions have been examined. Twenty-one have been suspected as CL. At least one sample was obtained from 18 patients. The lesions were predominantly old, more or less scarring and secondary infected. A skin smear was performed for 15 patients, a skin biopsy for 14 patients: smears and cultures were all negative. The PCR (Leishmania spp.) made on 14 biopsies was positive for 12 patients (86%). The low amount of amplified DNA obtained did not allow the sequencing and identification of the species of Leishmania. Western blot (WB) serology was positive in 11 cases out of 12 (92%). This investigation showed the presence of cutaneous leishmaniasis in Bandiagara. A further investigation is required during transmission period (September-October) to confirm the presence of Leishmania major epidemic in Dogon country.

In patients with malaria, parasitaemia is usually estimated by assuming 8000 white cell counts (WCC) per microlitre of blood. In a sample of 3044 African children under 5 years of age with uncomplicated falciparum malaria, parasitaemia estimated using standardised WCC was compared to parasitaemia calculated based on each child's own WCC. The two methods produced comparable results. However, WCC were8000 in under-fives with an inverse relationship with age, resulting in the standard approximation method significantly underestimating parasitaemia in the youngest age group and overestimating parasitaemia in the oldest age groups.

The group IIA human non-pancreatic secretory phospholipase A 2 (hnp-sPLA 2 ) is one of the enzymes implied in the inflammatory process. In the course of our work on inhibitors of this enzyme we investigated the influence of rigidity of the piperazine region on the biological activity. Several modifications were explored. Various linkers, such as amide, urea, carbamate, or alkoxyphenyl were inserted between the piperazine and the lipophilic chain. Also, modification of the piperazine core to incorporate carbonyl groups was studied. In an in vitro fluorimetric assay using the human GIIA (HPLA 2 ) and porcine pancreatic GIB enzymes, compound 60a (Y = phenoxy, R = C 18 H 37 , Z = CH 2 ) had the optimal activity with an IC 50 = 30 nM on HPLA 2 . By means of molecular modelling we attempted to get informations towards comprehension of differences in activity.

Background Artesunate and amodiaquine (AS&AQ) is at present the world's second most widely used artemisinin-based combination therapy (ACT). It was necessary to evaluate the efficacy of ACT, recently adopted by the World Health Organization (WHO) and deployed over 80 countries, in order to make an evidence-based drug policy. Methods An individual patient data (IPD) analysis was conducted on efficacy outcomes in 26 clinical studies in sub-Saharan Africa using the WHO protocol with similar primary and secondary endpoints. Results A total of 11,700 patients (75% under 5 years old), from 33 different sites in 16 countries were followed for 28 days. Loss to follow-up was 4.9% (575/11,700). AS&AQ was given to 5,897 patients. Of these, 82% (4,826/5,897) were included in randomized comparative trials with polymerase chain reaction (PCR) genotyping results and compared to 5,413 patients (half receiving an ACT). AS&AQ and other ACT comparators resulted in rapid clearance of fever and parasitaemia, superior to non-ACT. Using survival analysis on a modified intent-to-treat population, the Day 28 PCR-adjusted efficacy of AS&AQ was greater than 90% (the WHO cut-off) in 11/16 countries. In randomized comparative trials (n = 22), the crude efficacy of AS&AQ was 75.9% (95% CI 74.6–77.1) and the PCR-adjusted efficacy was 93.9% (95% CI 93.2–94.5). The risk (weighted by site) of failure PCR-adjusted of AS&AQ was significantly inferior to non-ACT, superior to dihydroartemisinin-piperaquine (DP, in one Ugandan site), and not different from AS+SP or AL (artemether-lumefantrine). The risk of gametocyte appearance and the carriage rate of AS&AQ was only greater in one Ugandan site compared to AL and DP, and lower compared to non-ACT (p = 0.001, for all comparisons). Anaemia recovery was not different than comparator groups, except in one site in Rwanda where the patients in the DP group had a slower recovery. Conclusion AS&AQ compares well to other treatments and meets the WHO efficacy criteria for use against falciparum malaria in many, but not all, the sub-Saharan African countries where it was studied. Efficacy varies between and within countries. An IPD analysis can inform general and local treatment policies. Ongoing monitoring evaluation is required.

In the 20th century malaria remains a major problem of public health in sub-Saharan Africa. This haemosporidium discovered in Africa by Laveran in 1880, kills one child every 30 seconds which amounts to three "tsunami" flowing each year into the African continent. The current international solidarity raises new hopes as regards the possibility to suppress the morbidity effects on the population's health condition. In order to be efficient, today's strategies (impregnated mosquito nets, intermittent preventive treatments, artemisinin based combination therapy) should reach at least 80% of the targeted population (pregnant women and children). By 2025, the uncontrolled urbanization of the African population and the social disorders will make a new population a target for malaria. The new data of functional genomics and proteonics open new avenues of research for new mechanisms, new therapeutics and vaccine targets and new tools of diagnosis and prognosis. The current candidate vaccines of the first generation have allowed the development of African competences in clinical trials of international standard. Although they represent scientific advances they will not resolve the problem of public health. Research on candidate vaccines of 2nd and 3rd generation remains a challenge for the international scientific community. Africa should play a determining role in this process. Scientific information on the field remains essential for these generations of new anti-malarial vaccines. The ethical aspects regarding those clinical trials and actions of public health and research remain an universal necessity Deontology and ethics are two complementary approaches for the good practice of medicine and research of a good practitioner. For the protection and advantages of the patient and/or volunteer of the research are the cornerstones of the ethical approach. The scientific quality of a research protocol submitted to an independent research ethics committee and the volunteer 's informed consent are universal ethical obligations. For the quality of ethics observance in a country reflects best the quality of the efficiency of its research system and its democracy.

As chloroquine and sulfadoxine-pyrimethamine (SP) are replaced by more effective artemisinin-based combination therapies (ACTs), strategies for monitoring (and, if possible, deterring) drug-resistant malaria must be updated and optimized. In vitro methods for measuring resistance will be critical for confirming and characterizing resistance to ACTs. Molecular markers are useful for tracking the emergence and dissemination of resistance and guiding treatment policy where resistance is low or moderate. Genomic approaches may help identify molecular markers for resistance to artemisinins and their partner drugs. Studies of reported ACT treatment failure should include assessing factors other than resistance that affect efficacy, including pharmacokinetics. Longitudinal clinical trials are particularly useful for comparing the benefits and risks of repeated treatment in high transmission settings. The malaria research and control community should not fail to exploit this opportunity to apply the lessons of the last 50 years to extend the useful therapeutic lives of ACTs.

Secreted phospholipases A2 (sPLA2s) have been reported to play an important role in various inflammatory conditions and thus represent an attractive therapeutic target. Previous SAR studies from our laboratory have revealed certain important features of our recently discovered specific hGIIA sPLA2 inhibitors, and we report here the synthesis and biological activities of glycerol-containing derivatives of our lead compound III (Figure 1). Efficient and selective synthesis methods have been developed to make glycerol trisubstituted by different groups on desired positions. In terms of biological activities, the best compounds (A3, A6, and A15) are more active than III (Figure 1), as potent as Me-Indoxam, an sPLA2s inhibitor of reference, against hGIIA, hGV, and hGX sPLA2s and at least 10 times less active toward the GIB enzymes in two in vitro assay systems. By synthesis of enantiopure (S)-A6, we demonstrated that no important improvement of the inhibitory potency could be achieved by this approach. Furthermore, the results show that the global lipophilicity is likely responsible for the anti-PLA2 activity and two oxadiazolone moieties seem too big to be accommodated by the active site of the hGIIA enzyme.

Residents of malaria-endemic areas sometimes spontaneously clear Plasmodium falciparum infection without drug treatment, implying an important role for host factors such as immunity in this clearance. Host factors may also contribute to clearance of parasites resistant to a treatment drug. Chloroquine resistance is caused by point mutations in P. falciparum chloroquine resistance transporter (pfcrt) gene. We investigated the clearance of malaria parasites carrying the key chloroquine resistance-conferring PfCRT mutation K76T in patients treated with chloroquine. We found that the ability to clear these resistant parasites is strongly dependent on age (the best surrogate for protective immunity in endemic areas), suggesting that host immunity plays a critical role in the clearance of resistant P. falciparum infections. Age-adjusted comparison of subjects able to clear resistant parasites and those unable to do so provides a new phenotype for identifying host immune and genetic factors responsible for protective immunity against malaria.