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Background: In Africa, many areas are co-endemic for the two major Schistosoma species, S. mansoni and S. haematobium. Epidemiological studies have suggested that host immunological factors may play an important role in co-endemic areas. As yet, little is known about differences in host immune responses and possible immunological interactions between S. mansoni and S. haematobium in humans. The aim of this study was to analyze host cytokine responses to antigens from either species in a population from a co-endemic focus, and relate these to S. mansoni and S. haematobium infection. Methodology: Whole blood cytokine responses were investigated in a population in the north of Senegal (n = 200). Blood was stimulated for 72 h with schistosomal egg and adult worm antigens of either Schistosoma species. IL-10, IL-5, IFN-γ, TNF-α, and IL-2 production was determined in culture supernatants. A multivariate (i.e. multi-response) approach was used to allow a joint analysis of all cytokines in relation to Schistosoma infection. Principal Findings: Schistosoma haematobium egg and worm antigens induced higher cytokine production, suggesting that S. haematobium may be more immunogenic than S. mansoni. However, both infections were strongly associated with similar, modified Th2 cytokine profiles. Conclusions/Significance: This study is the first to compare S. mansoni and S. haematobium cytokine responses in one population residing in a co-endemic area. These findings are in line with previous epidemiological studies that also suggested S. haematobium egg and worm stages to be more immunogenic than those of S. mansoni. Author Summary: In the developing world, over 207 million people are infected with blood-dwelling parasitic Schistosoma worms. Schistosoma haematobium and S. mansoni are the most widespread species. In Africa, they often occur together in the same area, with many people carrying both species. Yet, little is known about the differences in immune response that the human host develops against these two species. It is also unknown whether the presence of one species may affect the immune response to the other. We here investigated 200 people from an area in the north of Senegal where both species occur. They were examined for Schistosoma infections, as well as for immune responses to the two species. We observed that both infections were characterized by very similar cytokine responses. However, S. haematobium antigens induced higher levels of cytokines than S. mansoni. This suggests that S. haematobium may give rise to stronger immune responses, and may help to explain differences between the two most important Schistosoma species regarding the occurrence of infection and morbidity. [ABSTRACT FROM AUTHOR]

Background: In malarious areas of the world, a higher proportion of the population has blood group O than in non-malarious areas. This is probably due to a survival advantage conferred either by an attenuating effect on the course of or reduction in the risk of infection by plasmodial parasites. Here, the association between ABO blood group and incidence of placental malaria was assessed in order to determine the possible influence of the former on the latter. Methods: Data from a study in Lambaréné, Gabon, and data from three previously published reports of studies in The Gambia, Malawi and Sudan, were compiled and compared. ABO blood groups were cross-tabulated with placental malaria stratified by parity. Odds ratios (OR), stratified by parity, were calculated for the outcome, placental parasitaemia, and compared between blood group O vs. non-O mothers in all four studies. Random effects meta-analysis of data from individual studies from areas with perennial hyper/holoendemic transmission was performed. Results: In Gabon, the odds ratio (OR) for active placental parasitaemia in mothers with group O was 0.3 (95% CI 0.05-1.8) for primiparae and 0.7 (95% CI 0.3-1.8) for multiparae. The OR for primiparae in the published study from The Gambia was 3.0 (95% CI 1.2-7.3) and, in Malawi, 2.2 (95% CI 1.1-4.3). In the Sudanese study, no OR for primiparae could be calculated. The OR for placental parasitaemia in group O multiparae was 0.8 (95% CI 0.3-1.7) in the Gambia, 0.6 (95% CI 0.4-1.0) in Malawi and 0.4 (95% CI 0.1-1.8) in Sudan. Combining data from the three studies conducted in hyper-/holo-endemic settings (Gambia, Malawi, Gabon) the OR for placental malaria in blood group O multiparae was 0.65 (95% CI 0.44-0.96) and for primiparae 1.70 (95% CI 0.67-4.33). Conclusion: Studies conducted in The Gambia and Malawi suggest that blood group O confers a higher risk of active placental infection in primiparae, but a significantly lower risk in multiparae. These findings were not confirmed by the study from Gabon, in which statistically non-significant trends for reduced risk of placental parasitaemia in those with blood group O, regardless of parity, were observed. [ABSTRACT FROM AUTHOR]

Chronic Schistosoma infection is often characterized by a state of T cell hyporesponsiveness of the host. Suppression of dendritic cell (DC) function could be one of the mechanisms underlying this phenomenon, since Schistosoma antigens are potent modulators of dendritic cell function in vitro. Yet, it remains to be established whether DC function is modulated during chronic human Schistosoma infection in vivo. To address this question, the effect of Schistosoma haematobium infection on the function of human blood DC was evaluated. We found that plasmacytoid (pDC) and myeloid DC (mDC) from infected subjects were present at lower frequencies in peripheral blood and that mDC displayed lower expression levels of HLA-DR compared to those from uninfected individuals. Furthermore, mDC from infected subjects, but not pDC, were found to have a reduced capacity to respond to TLR ligands, as determined by MAPK signaling, cytokine production and expression of maturation markers. Moreover, the T cell activating capacity of TLR-matured mDC from infected subjects was lower, likely as a result of reduced HLA-DR expression. Collectively these data show that S. haematobium infection is associated with functional impairment of human DC function in vivo and provide new insights into the underlying mechanisms of T cell hyporesponsiveness during chronic schistosomiasis. Author Summary: A key feature of schistosomiasis, as well as of other systemic helminth infections, is their chronic nature. This reflects the successful evasion and suppression of host immune responses by the parasites. One of the mechanisms that could underlie this phenomenon is modulation of the dendritic cells (DC), which play a central role in initiation and control of T cell responses. Although several in vitro studies have documented the modulatory capacity of Schistosoma antigens on DC function, it is still unclear what effect schistosomiasis has on human DC function in vivo. To address this question, we isolated the two main DC subsets present in peripheral blood from infected and uninfected individuals living in a Schistosoma-endemic area in central Africa, and found that specifically the myeloid DC from Schistosoma-infected subjects displayed an impaired capacity to respond to Toll-like receptor ligands and to drive T cell responses. These findings provide new insights into how schistosomiasis suppresses host immune responses, which can be exploited for new strategies to enhance immunity against the parasites. [ABSTRACT FROM AUTHOR]

Background: Allergic diseases seem less prevalent in communities in less developed parts of the world, where parasite infections are highly prevalent. Altogether not much is known about the association between chronic infections with tissue and blood-dwelling parasites and atopy. Methods: In an area in Gabon endemic for blood and tissue parasites, 520 schoolchildren were parasitologically examined and skin prick-tested for a set of common environmental aeroallergens. Levels of allergen-specific IgE and polyclonal IgE were measured. Results: In schoolchildren schistosome and filarial infections increased with age, whereas malaria was more prevalent in younger children. In contrast to allergen sensitization that increased with age, skin test reactivity tended to decline. The number of children with mite-specific IgE antibodies (47%) by far exceeded the number responding to skin prick testing (11%). Mite sensitization was found to be the highest in children infected with schistosomes and/or filariae whereas skin test reactivity was lowest. The multiple logistic regression showed that the risk of a positive skin test was 8-fold higher with increasing levels of mite-specific IgE but was reduced by 72% when infected with blood stage helminths. Conclusions: Chronic blood and tissue parasite infections that are often capable of modulating immune responses in the host are negatively associated with skin test reactivity in a sensitized population.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

An essay is presented on the seasonal pattern of influenza in the temperate areas compared to tropical regions especially in Africa. It mentions that influenza activity displays a seasonal pattern in temperate areas in which it reaches its peak during winter while in tropics, it is present all year round. It mentions that World Health Organization (WHO) Flu Net based in Europe and North America closely monitored the pandemic especially in Southeast Asia, Latin America and Africa.

The article focuses on major health and socioeconomic challenges faced by rapid transmission of COVID-19 in Africa, and might reveal innovative solutions. It mentions that the distribution of pandemic cases and deaths reveals surprisingly low rates in Africa, despite comparable levels of testing per confirmed cases across continents.

This study investigated in utero priming as a consequence of maternal parasitic infections. Cord blood plasma samples of 63 African newborns were assessed by enzyme-linked immunosorbent assay for their content of total and schistosome-specific or filaria-specific IgE and IgG4. The frequencies of lymphocyte phenotypes in cord blood were also determined by using flow cytometry, and were compared with those of European newborns. We found significantly increased schistosome soluble egg antigen (SEA)-specific IgE in cord plasma of those born to mothers with schistosome infections and correlations between fetal and maternal SEA-specific and filaria antigen-specific IgE. These data are evidence for in utero priming of the fetal immune system to maternal helminth infections. Furthermore, we show significantly enhanced percentages of CD5- B cells in African newborns cord blood compared with Europeans, which is consistent with earlier maturation of the African fetal immune system.

Purpose of Review: Allergic diseases have only recently gained serious attention in Africa. This review discusses recent studies that have focused on allergy among Africans and people of African ancestry., Recent Findings: Time trend studies of the prevalence of allergies in Africa show a consistent increase over a period of 7-10 years. Recent studies have reported that the link between IgE, skin reactivity to allergens and allergic symptoms increases with increasing gross national income of the country. Association between helminth infections, and allergies seem contradictory, which may be attributed to differences in the length of infection and species studied. Importantly, researchers have identified an 'urban diet' component, which is associated with increased skin reactivity to allergens. Finally, whereas Africans in rural Africa seem to suffer less from allergies, people of African ancestry in affluent countries have higher prevalence and greater severity of allergic symptoms than natives of these host countries, raising important issues on genetic control of allergic diseases., Summary: Mechanisms underlying the development of allergy are a complex interaction of genetic susceptibility and environmental exposures. Identification of specific environmental factors, mechanistic pathways and genetic risk factors in sufficiently powered studies will be necessary to better understand and control the allergic march in Africa and elsewhere.