Several studies have focused their attention on the relationship between host genetic factors and susceptibility/resistance to severe malaria. However, there is a paucity of information concerning the role of host genetic factors in asymptomatic malaria, a form of low-grade Plasmodium falciparum infection without clinical symptoms. We investigated in this study the potential relationship between the host (human) genetic polymorphisms (glucose-6-phosphate dehydrogenase [G6PD], mannose binding lectin [MBL], tumor necrosis factor ␣ [TNF␣] −308 and-238 , and nitric oxide synthase 2 [NOS2]-954) and the prevalence and profile of asymptomatic P. falciparum infection in 158 Gabonese schoolchildren. We found that G6PD Aheterozygous females (18 of 74) have a low prevalence of asymptomatic malaria (38.9% versus 67.3%; P ‫ס‬ 0.03, by chi-square test). Children heterozygous for TNF␣-238 (25 of 156) carry high number of diverse infecting parasite genotypes (2.5 versus 1.99; variance F ‫ס‬ 3.05). No statistically significant association was found between MBL, TNF␣-308 , or NOS2 polymorphisms and asymptomatic malaria. Upon combining our data on asymptomatic forms with those from the literature for others forms, we conclude that G6PD Aheterozygous females are protected against all forms of P. falciparum malaria, and that the TNF␣-238A allele confers protection against clinical malaria.

Mannose-binding lectin (MBL) plays an important role in the early stages of primary infections and during the decay of maternal antibodies in infants. Various studies have looked at the relation between serum MBL concentrations, MBL gene alterations and susceptibility to infections. We investigated the distribution of variant MBL alleles in 626 unrelated adults from sub-Saharan African countries and looked for a potential relation between these alleles and the incidence, prevalence and death rate of tuberculosis for sub-Saharan Africa. We also evaluated the relation between MBL genotypes and susceptibility to HIV-1 infection in 188 Gabonese adults. We found that (i) the prevalence of the common variant MBL alleles is correlated with the incidence of tuberculosis in sub-Saharan Africa (r ¼ 0.565), (ii) the mutant MBL G57E allele, in either the homozygous or compound heterozygous state, is associated with susceptibility to HIV-1 infection in the Gabonese population (P ¼ 0.019).Our data plus those in the literature suggest that individuals who are homozygous for the mutant MBL alleles display increased susceptibility to infections. Interestingly, we found that individuals who are heterozygous for MBL mutations are much less susceptible to infections than those who are homozygous for the wild-type MBL allele.

Introduction Blood-borne pathogens such as human immunodeficiency virus (HIV), hepatitis B and C (HBV and HCV) viruses and Treponema pallidum remain a major public health problem in sub-Saharan Africa. The purpose of this study was to assess the frequency and clinical implications of HIV, HBV, HCV and Treponema pallidum markers in blood donors in a rural area of Southeast Gabon (Koula-Moutou) from 2012 to 2017. Methods Hepatitis B surface antigen (HBsAg), anti-HIV, anti-HCV and anti- Treponema pallidum antibodies were screened using rapid diagnostic tests (RDTs). Results Of a total of 5,706 blood donors, 1,054 (18.5%) were seropositive for at least one infectious marker and 59 (5.6%) had serologic evidence of multiple infections. The overall seroprevalence of HIV, HBsAg, HCV, and syphilis was 3.1%; 5.9%; 6.2% and 3.3%, respectively. HIV, syphilis and HCV distributions were associated with neither the sex nor the age of the donors. Only HBsAg seroprevalence was significantly higher in donors of the age group 26-35 years old compared to donors of the age group 36-45 years (OR = 1.43 (95% CI: 1.01-2.04), P = 0.045). There was a significant increase in the frequencies of HIV and syphilis and a regression of HBsAg and HCV among blood donors. Conclusion This study presents the epidemiology of the main pathogens detected in blood donors in a rural area in Gabon. We found that the overall distribution of transfusion transmitted infectious diseases were lower than those observed in the general population but could be underestimated due to the use of RDTs in the screening process of the blood donations.