Leishmaniases in West Africa: Past and Current

Leishmaniases are vector-borne diseases. Cutaneous leishmaniasis (CL) is endemic in West Africa. Sporadic and anecdotal cases of visceral leishmaniasis (VL) have been reported in the past. Recent data showed the changing of epidemiology of leishmaniases in West Africa, with the occurrence of outbreak of CL due to Leishmania major in urban and rural areas. CL is transmitted by Phlebotomus duboscqi. The role of Sergentomyia (Spelaeomyia) darlingi as vector in rural areas has been evoked but not confirmed. Cases of VL due to Leishmania spp. have been described in West Africa; however, parasites species were not identified and dogs were suspected to be the reservoir. No humans’ case of symptomatic VL due to L. infantum has been described in West Africa. Recent data in rural areas of Senegal confirmed dog as reservoir of L. infantum. In the same study in Senegal, Sergentomyia sandflies were found infected with L. infantum, indicating a possible role in leishmaniasis transmission. Coinfection leishmaniases-HIV is reported but rare. In this chapter, we included most recent publications and propose an updated landscape of CL and VL epidemiology in West Africa

Malaria Transmission-Blocking Vaccines: Present Status and Future Perspectives

Transmission-blocking vaccines (TBVs) utilize Plasmodium sexual stage proteins to induce antibodies that prevent parasites from infecting blood-fed mosquitoes. This type of vaccine, which can be considered a “vaccine of solidarity,” reduces Plasmodium infections within communities without conferring direct protective immunity to the vaccine recipients. The leading TBV candidates have advanced to field clinical trials, where vaccine-induced antibody function has been demonstrated in mosquito-feeding assays. However, the duration of functional antibody responses has been short-lived; hence current development has focused on improved adjuvant and vaccine delivery systems to generate long-lasting immune responses. For the future implementation of TBVs, community perceptions and understandings should be considered, and education should be provided on the concept and its value. Implementation will need to be undertaken in harmony with current malaria control policies

Use of a pLDH-based dipstick in the diagnostic and therapeutic follow-up of malaria patients in Mali

<p>Abstract</p> <p>Background</p> <p>Malaria is a major public health problem in Mali and diagnosis is typically based on microscopy. Microscopy requires a well trained technician, a reliable power source, a functioning microscope and adequate supplies. The scarcity of resources of community health centres (CHC) does not allow for such a significant investment in only one aspect of malaria control. In this context, Rapid Diagnostic Tests (RDTs) may improve case management particularly in remote areas.</p> <p>Methods</p> <p>This multicentre study included 725 patients simultaneously screened with OptiMal-IT test and thick smears for malaria parasite detection. While evaluating the therapeutic efficacy of choroquine in 2 study sites, we compared the diagnostic values of thick smear microscopy to OptiMal-IT test applying the WHO 14 days follow-up scheme using samples collected from 344 patients.</p> <p>Results</p> <p>The sensitivity and the specificity of OptiMal-IT compared to thick smear was 97.2% and 95.4%, whereas the positive and negative predictive values were 96.7 and 96.1%, respectively. The percent agreement between the two diagnostic tests was 0.93. The two tests were comparable in detecting malaria at day 0, day 3 and day 14. The only difference was observed at day 7 due to high gametocytemia. Subjectively, health care providers found OptiMal-IT easier to use and store under field conditions.</p> <p>Conclusion</p> <p>OptiMal-IT test revealed similar results when compared to microscopy which is considered the gold standard for malaria diagnostics. The test was found to have a short processing time and was easier to use. These advantages may improve malaria case management by providing a diagnostic and drug efficacy follow-up tool to peripheral health centres with limited resources.</p

Ethical Data Release in Genome-Wide Association Studies in Developing Countries

Michael Parker and colleagues discuss the ethical issues associated with data release from genome-wide association studies in developing countries

SPODT: An R Package to Perform Spatial Partitioning

International audienceSpatial cluster detection is a classical question in epidemiology: Are cases located near other cases? In order to classify a study area into zones of different risks and determine their boundaries, we have developed a spatial partitioning method based on oblique decision trees, which is called spatial oblique decision tree (SpODT). This non-parametric method is based on the classification and regression tree (CART) approach introduced by Leo Breiman. Applied to epidemiological spatial data, the algorithm recursively searches among the coordinates for a threshold or a boundary between zones, so that the risks estimated in these zones are as different as possible. While the CART algorithm leads to rectangular zones, providing perpendicular splits of longitudes and latitudes, the SpODT algorithm provides oblique splitting of the study area, which is more appropriate and accurate for spatial epidemiology. Oblique decision trees can be considered as non-parametric regression models. Beyond the basic function, we have developed a set of functions that enable extended analyses of spatial data, providing: inference, graphical representations, spatio-temporal analysis, adjustments on covariates, spatial weighted partition, and the gathering of similar adjacent final classes. In this paper, we propose a new R package, SPODT, which provides an extensible set of functions for partitioning spatial and spatio-temporal data. The implementation and extensions of the algorithm are described. Function usage examples are proposed, looking for clustering malaria episodes in Bandiagara, Mali, and samples showing three different cluster shapes

Access and use of interventions to prevent and treat malaria among pregnant women in Kenya and Mali: a qualitative study.

BACKGROUND: Coverage of malaria in pregnancy interventions in sub-Saharan Africa is suboptimal. We undertook a systematic examination of the operational, socio-economic and cultural constraints to pregnant women's access to intermittent preventive treatment (IPTp), long-lasting insecticide-treated nets (LLINs) and case management in Kenya and Mali to provide empirical evidence for strategies to improve coverage. METHODS: Focus group discussions (FGDs) were held as part of a programme of research to explore the delivery, access and use of interventions to control malaria in pregnancy. FGDs were held with four sub-groups: non-pregnant women of child bearing age (aged 15-49 years), pregnant women or mothers of children aged <1 year, adolescent women, and men. Content analysis was used to develop themes and sub-themes from the data. RESULTS: Women and men's perceptions of the benefits of antenatal care were generally positive; motivation among women consisted of maintaining a healthy pregnancy, disease prevention in mother and foetus, checking the position of the baby in preparation for delivery, and ensuring admission to a facility in case of complications. Barriers to accessing care related to the quality of the health provider-client interaction, perceived health provider skills and malpractice, drug availability, and cost of services. Pregnant women perceived themselves and their babies at particular risk from malaria, and valued diagnosis and treatment from a health professional, but cost of treatment at health facilities drove women to use herbal remedies or drugs bought from shops. Women lacked information on the safety, efficacy and side effects of antimalarial use in pregnancy. CONCLUSION: Women in these settings appreciated the benefits of antenatal care and yet health services in both countries are losing women to follow-up due to factors that can be improved with greater political will. Antenatal services need to be patient-centred, free-of-charge or highly affordable and accountable to the women they serve

Differences in Fcgamma receptor IIa genotypes and IgG subclass pattern of anti-malarial antibodies between sympatric ethnic groups in Mali

<p>Abstract</p> <p>Background</p> <p>The Ig Fc receptor family is an important link between the humoral and cellular immune systems. The association of a dimorphism in amino acid 131 (R/H) of the FcγRIIa with malaria severity, the R-allele being associated with a milder disease outcome, led to the investigation of the possible impact of this polymorphism in the interethnic difference in malaria susceptibility seen between the Fulani and Dogon in Mali.</p> <p>Methods</p> <p>Plasma from individuals from Mali (164 Fulani and 164 Dogon) were analysed for malaria-reactive and total IgG subclass antibodies using ELISA, and the same individuals were also genotyped for the FcγRIIa R131H polymorphism using RFLP-PCR. Statistical analyses of the IgG subclass levels were done by unpaired t-test and ANOVA, and genotype differences were tested by χ²-test.</p> <p>Results</p> <p>While the two ethnic groups showed a similar frequency of the FcγRIIa 131 R/H heterozygote genotype, 131R/R dominated over the 131 H/H genotype in the Dogon whereas the Fulani presented a similar frequency of the two homozygote genotypes. The two alleles were evenly distributed in the Fulani, while the Dogon were clearly biased towards the R-allele. The Fulani showed higher levels of anti-malarial IgG1, -2 and -3 antibodies, with a higher proportion of IgG2, than the Dogon. In the Fulani, H-allele carriers had higher anti-malarial IgG2 levels than R/R homozygotes, while in the Dogon, the R-allele carriers showed the higher IgG2 levels. For anti-malarial IgG3, the R-allele carriers in the Fulani had higher levels than the H/H homozygotes.</p> <p>Conclusion</p> <p>Taken together, the results showed marked interethnic differences in FcγRIIa R131H genotypes. Furthermore, the results indicate that the FcγRIIa R131H genotype may influence the IgG subclass responses related to protection against malaria, and that IgG2 may be of importance in this context.</p

Valid Consent for Genomic Epidemiology in Developing Countries

Drawing on experience gained from ongoing research in Mali, this paper describes practical ethical challenges relating to the achievement of valid consent in genomic epidemiology

Epigenetics and Malaria Susceptibility/Protection: A Missing Piece of the Puzzle

A better understanding of stable changes in regulation of gene expression that result from epigenetic events is of great relevance in the development of strategies to prevent and treat infectious diseases. Histone modification and DNA methylation are key epigenetic mechanisms that can be regarded as marks, which ensure an accurate transmission of the chromatin states and gene expression profiles over generations of cells. There is an increasing list of these modifications, and the complexity of their action is just beginning to be understood. It is clear that the epigenetic landscape plays a fundamental role in most biological processes that involve the manipulation and expression of DNA. Although the molecular mechanism of gene regulation is relatively well understood, the hierarchical order of events and dependencies that lead to protection against infection remain largely unknown. In this review, we propose that host epigenetics is an essential, though relatively under studied, factor in the protection or susceptibility to malaria