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IntroductionSeroprevalence of anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies in the postvaccination period in Kenya remains to be elucidated. This study aimed to determine the seroprevalence of anti-SARS-CoV-2 IgM and IgG and evaluate Covid-19 vaccination uptake in a university setting in Nairobi.MethodsThis cross-sectional study assayed serum anti-SARS-CoV-2 IgM and IgG levels using enzyme-linked immunosorbent assays. A structured questionnaire was used to determine vaccine uptake, vaccine hesitancy and reasons for hesitancy.ResultsA total of 189 participants were enrolled (median age, 21 years; female, 50.8%). The seroprevalence of anti-SARS-CoV-2 was 12.7% for IgM and 87.8% for IgG. Anti-SARS-CoV-2 IgG titers were higher among the vaccinated vs. non-vaccinated individuals (p < 0.001, U = 2817.5), females vs. males (p = 0.024, U = 3616), and those vaccinated ≤ 6 months before the study vs. those vaccinated >1 year earlier (p = 0.002, H = 12.359). The vaccination hesitancy rate was 43.4% and the underlying reasons included mistrust (22.4%), health concerns (19.7%), and lack of information (18.4%).DiscussionThe high seroprevalence of anti-SARS-CoV-2 IgG is an indication of high exposure to SARS-CoV-2 either through natural infection or through vaccination. The high vaccine hesitancy noted necessitates community engagement, and public education to dispel myths and misinformation prior to roll out of new vaccines and other health interventions.

IntroductionSchistosomiasis (Bilharzia), a neglected tropical disease caused by Schistosoma parasites, afflicts over 240 million people globally, disproportionately impacting Sub-Saharan Africa. Current diagnostic tests, despite their utility, suffer from limitations like low sensitivity. Polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) remain the most common and sensitive nucleic acid amplification tests. Still, the sensitivity of nucleic acid amplification tests is significantly affected by the copy number of amplification targets, resulting in underestimation of true Schistosoma infections, especially in low transmission settings. Additionally, lengthy qPCR run times pose challenges when dealing with large sample volumes and limited resources. In this study, the identical multi-repeat sequences (IMRS) were used as a novel approach to enhance the sensitivity of nucleic acid-based Bilharzia diagnosis.MethodsTo identify novel genomic repeat regions, we utilized the IMRS algorithm, with modifications to enable larger target region (100-200bp) identification instead of smaller sequences (18-30bp). These regions enabled customised primer-probe design to suit requirements for qPCR assay. To lower the qPCR amplification times, the assay was conducted using fast cycling condition. Regression analysis, and qPCR data visualization was conducted using Python programming.ResultsUsing Schistosoma mansoni and S. haematobium, we found that IMRS-based qPCR, employing genus-specific primers and TaqMan probes, offers exceptional analytical sensitivity, detecting as little as a single genome copy per microliter within 36 minutes.DiscussionThe lowest concentration of DNA detected using IMRS-based PCR and qPCR represented tenfold improvement over conventional PCR. As part of further development, there is a need to compare IMRS-based qPCR against other qPCR methods for Schistosoma spp. Nonetheless, IMRS-based diagnostics promise a significant advancement in bilharzia diagnosis, particularly in low-transmission settings, potentially facilitating more effective control and treatment strategies.

The potential consequences of parasitic infections on a person’s immune responsiveness to unrelated antigens are often conjectured upon in relationship to allergic responses and autoimmune diseases. These considerations sometimes extend to whether parasitic infection of pregnant women can influence the outcomes of responses by their offspring to the immunizations administered during national Expanded Programs of Immunization. To provide additional data to these discussions, we have enrolled 99 close-to-term pregnant women in western Kenya and determined their Schistosoma mansoni and Plasmodium falciparum infection status. At 2 years of age, when the initial immunization schedule was complete, we determined their children’s IgG antibody levels to tetanus toxoid, diphtheria toxoid, and measles nucleoprotein (N-protein) antigens using a multiplex assay. We also monitored antibody responses during the children’s first 2 years of life to P. falciparum MSP119 (PfMSP119), S. mansoni Soluble Egg Antigen (SEA), Ascaris suum hemoglobin (AsHb), and Strongyloides stercoralis (SsNIE). Mothers’ infections with either P. falciparum or S. mansoni had no impact on the level of antibody responses of their offspring or the proportion of offspring that developed protective levels of antibodies to either tetanus or diphtheria antigens at 2 years of age. However, children born of S. mansoni-positive mothers and immunized for measles at 9 months of age had significantly lower levels of anti-measles N-protein antibodies when they were 2 years old (p = 0.007) and a lower proportion of these children (62.5 vs. 90.2%, OR = 0.18, 95% CI = 0.04–0.68, p = 0.011) were considered positive for measles N-protein antibodies. Decreased levels of measles antibodies may render these children more susceptible to measles infection than children whose mothers did not have schistosomiasis. None of the children demonstrated responses to AsHb or SsNIE during the study period. Anti-SEA and anti-PfMSP119 responses suggested that 6 and 70% of the children acquired schistosomes and falciparum malaria, respectively, during the first 2 years of life.