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Standard entomological methods for evaluating the impact of vector control lack sensitivity in low-malaria-risk areas. The detection of human IgG specific to Anopheles gSG6-P1 salivary antigen reflects a direct measure of human-vector contact. This study aimed to assess the effectiveness of a range of vector control measures (VCMs) in urban settings by using this biomarker approach. The study was conducted from October to December 2008 on 2,774 residents of 45 districts of urban Dakar. IgG responses to gSG6-P1 and the use of malaria VCMs highly varied between districts. At the district level, specific IgG levels significantly increased with age and decreased with season and with VCM use. The use of insecticide-treated nets, by drastically reducing specific IgG levels, was by far the most efficient VCM regardless of age, season or exposure level to mosquito bites. The use of spray bombs was also associated with a significant reduction of specific IgG levels, whereas the use of mosquito coils or electric fans/air conditioning did not show a significant effect. Human IgG response to gSG6-P1 as biomarker of vector exposure represents a reliable alternative for accurately assessing the effectiveness of malaria VCM in low-malaria-risk areas. This biomarker tool could be especially relevant for malaria control monitoring and surveillance programmes in low-exposure/low-transmission settings.

BackgroundIn Benin, as of April 12, 2023, 28,014 cases and 163 deaths of coronavirus disease (COVID-19) had been notified. COVID-19 disease has been associated with an increased risk of preterm birth, caesarean delivery and maternal morbidity. However, few studies have evaluated the extent of SARS-CoV-2 infection among pregnant women in sub-Saharan African countries. In this EDCTP-funded COVID-19 surveillance project, we aimed to determine SARS-CoV-2 seroprevalence and identify factors associated with seropositivity among pregnant women in Benin. MethodsA cross-sectional study was carried out between April and June 2022 in Allada, a middle-size city in southern Benin, and Natitingou, a city located 500 kilometres North. Pregnant women in their third trimester of pregnancy were recruited at study antenatal care clinics. A rapid diagnostic test for detection of IgG/IgM against the receptor binding domain of SARS-CoV-2 spike protein was performed, and socio-demographic and clinical characteristics of the participants were recorded. ResultsA total of 861 women were included in the study. Mean age of study participants was 26.4 years, and their mean gestational age was 35.0 weeks. SARS-CoV-2 antibodies were detected in 75.7% (95%CI 75.6%-78.6%) of non-vaccinated participants. Only 6.7% (95%CI 5.15–8.62%) of the participants reported to had been vaccinated against COVID-19. Unvaccinated participants from Allada who had at least one previous morbidity had an almost three-fold increased risk of presenting SARS-CoV-2 antibodies (OR=2.89 [1.19–7.00]). None of the participants had been diagnosed/tested for COVID-19 during their pregnancy.ConclusionThe SARS-CoV-2 virus has circulated greatly among pregnant women from Benin. Despite none of the participants had been diagnosed with COVID-19, three out of four participants presented SARS-CoV-2 antibodies, suggesting that COVID-19 cases were asymptomatic or remained undetected by the national surveillance systems.

Background Placental malaria (PM) is associated with poor foetal development, but the pathophysiological processes involved are poorly understood. Cyclooxygenase (COX) and lipoxygenase (LOX) which convert fatty acids to prostaglandins and leukotrienes, play important roles in pregnancy and foetal development. COX-2, currently targeted by specific drugs, plays a dual role as it associates with both pre-eclampsia pathology and recovery during infection. The role of COX during PM was questioned by quantifying at delivery COX-1, COX-2, 15-LOX, and IL-10 expression in two groups of malaria infected and uninfected placenta. Methods Placental biopsies were collected at delivery for mRNA isolation and quantification, using real time PCR. Results COX-2 and IL-10 mRNAs increased mainly during chronic infections (nine- and five-times, respectively), whereas COX-1 transcripts remained constant. COX-2 over-expression was associated with a higher birth weight of the baby, but with a lower rate of haemoglobin of the mother. It was associated with a macrophage infiltration of the placenta and with a low haemozoin infiltration. In the opposite way, placental infection was associated with lower expression of 15-LOX mRNA. A high degree of haemozoin deposition correlates with low birth weight and decreased expression of COX-2. Conclusion These data provide evidence that COX-2 and IL-10 are highly induced during chronic infection of the placenta, but were not associated with preterm delivery or low birth weight. The data support the involvement of COX-2 in the recovery phase of the placental infection.

Standard entomological methods for evaluating the impact of vector control lack sensitivity in low-malaria-risk areas. The detection of human IgG specific to Anopheles gSG6-P1 salivary antigen reflects a direct measure of human-vector contact. This study aimed to assess the effectiveness of a range of vector control measures (VCMs) in urban settings by using this biomarker approach. The study was conducted from October to December 2008 on 2,774 residents of 45 districts of urban Dakar. IgG responses to gSG6-P1 and the use of malaria VCMs highly varied between districts. At the district level, specific IgG levels significantly increased with age and decreased with season and with VCM use. The use of insecticide-treated nets, by drastically reducing specific IgG levels, was by far the most efficient VCM regardless of age, season or exposure level to mosquito bites. The use of spray bombs was also associated with a significant reduction of specific IgG levels, whereas the use of mosquito coils or electric fans/air conditioning did not show a significant effect. Human IgG response to gSG6-P1 as biomarker of vector exposure represents a reliable alternative for accurately assessing the effectiveness of malaria VCM in low-malaria-risk areas. This biomarker tool could be especially relevant for malaria control monitoring and surveillance programmes in low-exposure/low-transmission settings.

Using stringent Western blot (WB) criteria, human T cell lymphotropic virus (HTLV) type I seroprevalence among 3783 persons from representative rural populations of Cameroon averaged 1.1% and was higher in females (1.5%) and in Pygmies (2.0%), increasing with age. Furthermore, an HTLV-I Gag-indeterminate WB profile (HGIP), exhibiting strong reactivities to p19, p26, p28, p32, p36, and pr 53 but lacking both p24 and env reactivity, was observed in 1.6% of the same populations. The prevalence of the HGIP was similar between males and females, did not increase with age, and appeared to cluster in tropical forests of southern Cameroon, especially among Pygmies (reaching 4%). These contrasting epidemiologic features, together with the lack of detection by polymerase chain reaction of HTLV-I sequences in the peripheral blood mononuclear cells of the persons with HGIP, strongly suggest that such a WB profile does not appear to reflect an HTLV-I-related viral infection but possibly an environmental (viral or parasitic) factor endemic in tropical rain forest areas.

We report characterization of a human T-cell lymphotropic virus type II (HTLV-II) isolated from an interleukin 2-dependent CD8 T-cell line derived from peripheral blood mononuclear cells of a healthy, HTLV-II-seropositive female Bakola Pygmy, aged 59, living in a remote equatorial forest area in south Cameroon. This HTLV-II isolate, designated PYGCAM-1, reacted in an indirect immunofluorescence assay with HTLV-II and HTLV-I polyclonal antibodies and with an HTLV-I/II gp46 monoclonal antibody but not with HTLV-I gag p19 or p24 monoclonal antibodies. The cell line produced HTLV-I/II p24 core antigen and retroviral particles. The entire env gene (1462 bp) and most of the long terminal repeat (715 bp) of the PYGCAM-1 provirus were amplified by the polymerase chain reaction using HTLV-II-specific primers. Comparison with the long terminal repeat and envelope sequences of prototype HTLV-II strains indicated that PYGCAM-1 belongs to the subtype B group, as it has only 0.5-2% nucleotide divergence from HTLV-II B strains. The finding of antibodies to HTLV-II in sera taken from the father of the woman in 1984 and from three unrelated members of the same population strongly suggests that PYGCAM-1 is a genuine HTLV-II that has been present in this isolated population for a long time. The low genetic divergence of this African isolate from American isolates raises questions about the genetic variability over time and the origin and dissemination of HTLV-II, hitherto considered to be predominantly a New World virus.