In a context where SARS-CoV-2 population-wide testing is implemented, clinical features and antibody response in those infected have never been documented in Africa. Yet, the information provided by analyzing data from population-wide testing is critical to understand the infection dynamics and devise control strategies. We described clinical features and assessed antibody response in people screened for SARS-CoV-2 infection. We analyzed data from a cohort of 3464 people that we molecularly screened for SARS-CoV-2 infection in our routine activity. We recorded people SARS-CoV-2 diagnosis, age, gender, blood types, white blood cells (WBC), symptoms, chronic disease status and time to SARS-CoV-2 RT-PCR conversion from positive to negative. We calculated the age-based distribution of SARS-CoV-2 infection, analyzed the proportion and the spectrum of COVID-19 severity. Furthermore, in a nested sub-study, we screened 83 COVID-19 patients and 319 contact-cases for anti-SARS-CoV-2 antibodies. Males and females accounted for respectively 51% and 49% of people screened. The studied population median and mean age were both 39 years. 592 out of 3464 people (17.2%) were diagnosed with SARS-CoV-2 infection with males and females representing, respectively, 53% and 47%. The median and mean ages of SARS-CoV-2 infected subjects were 37 and 38 years respectively. The lowest rate of infection (8%) was observed in the elderly (aged > 60). The rate of SARS-Cov-2 infection in both young (18–35 years old) and middle-aged adults (36–60 years old) was around 20%. The analysis of SARS-CoV-2 infection age distribution showed that middle-aged adults accounted for 54.7% of SARS-CoV-2 positive persons, followed respectively by young adults (33.7%), children (7.7%) and elderly (3.8%). 68% (N = 402) of SARS-CoV-2 infected persons were asymptomatic, 26.3% (N = 156) had influenza-like symptoms, 2.7% (N = 16) had influenza-like symptoms associated with anosmia and ageusia, 2% (N = 11) had dyspnea and 1% (N = 7) had respiratory failure, which resulted in death. Data also showed that 12% of SARS-CoV-2 infected subjects, had chronic diseases. Hypertension, diabetes, and asthma were the top concurrent chronic diseases representing respectively 58%, 25% and 12% of recorded chronic diseases. Half of SARS-CoV-2 RT-PCR positive patients were cured within 14 days following the initiation of the anti-COVID-19 treatment protocol. 78.3% of COVID-19 patients and 55% of SARS-CoV-2 RT-PCR confirmed negative contact-cases were positive for anti-SARS-CoV-2 antibodies. Patients with severe-to-critical illness have higher leukocytes, higher neutrophils and lower lymphocyte counts contrarily to asymptomatic patients and patients with mild-to-moderate illness. Neutrophilic leukopenia was more prevalent in asymptomatic patients and patients with mild-to-moderate disease for 4 weeks after diagnosis (27.1–42.1%). In Patients with severe-to-critical illness, neutrophilic leukocytosis or neutrophilia (35.6–50%) and lymphocytopenia (20–40%) were more frequent. More than 60% of participants were blood type O. It is also important to note that infection rate was slightly higher among A and B blood types compared with type O. In this African setting, young and middle-aged adults are most likely driving community transmission of COVID-19. The rate of critical disease is relatively low. The high rate of anti-SARS-CoV-2 antibodies observed in SARS-CoV-2 RT-PCR negative contact cases suggests that subclinical infection may have been overlooked in our setting.

Background Evaluating malaria control strategies for pregnant women is essential. The objective of this study was to determine the factors influencing antenatal care (ANC) visit attendance, complete intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and its impact on the health of pregnant women and their newborn babies living in semi-urban and rural areas of southeastern Gabon. Methods This transversal study was performed at the Centre Hospitalier Régional Paul Moukambi de Koula-Moutou (CHRPMK). Information regarding age, frequency of prenatal consultations, obstetric history, use of malaria control measures, use of IPTp-SP, malaria diagnostic of women and their newborns, were collected: (i): from birth registers from 1 January, 2018 to 31 December, 2019 and, (ii): a questionnaire from January to April 2020. Results In total, 1,851 and 323 pregnant women were included during the first and the second sub-set of study, respectively. In the first sub-set of data, the mean age was 26.18 ± 7.02 years and 96.54% (1,787/1,851) of pregnant women had attended ANC service but 54.45% had complete ANC visit attendance (at least 4 ANC). The complete ANC visit was linked with age (p < 0.001) and profession (p < 0.001). The complete IPTp-SP (at least 3 doses) was 58.87%. Complete IPTp-SP was linked to profession (aOR = 1.49, 95% CI [1.04–2.18], p < 0.001), ANC visit (aOR = 0.176, 95% CI [0.14–0.22], p < 0.034) and age (p = 0.03). Birth weight was higher for babies whose mothers had received complete IPTp-SP (p < 0,001) but the Apgar score was not influenced by the use of IPTp-SP (p = 0.71). In the second sub-set of data, the prevalence of plasmodial infection was 3.10% (95% IC [1.21–5]) and Plasmodium falciparum was responsible for 100% of infections. The prevalence of plasmodial infection was the same for all age groups (p = 0.69), gravidity (p = 0.13) and domestic control measures (p > 0.05). A low birth weight was statistically linked to the mother’s plasmodial infection (p < 0.01). Furthermore, plasmodial infection was statistically linked to premature birth (p < 0.001). Conclusions It was observed that attendance of women to ANC service and a complete IPTp-SP course is insufficient.

Plasmodium falciparum merozoite antigens (PfMAgs) play an essential role in the development of immunity to malaria. Currently, P. falciparum: protein 113 (Pf 113), apical membrane antigen 1 (AMA1), erythrocyte binding antigens (EBA175), and reticulocyte binding protein homologue 5 (RH5) are among the most PfMAgs studied. A comparative analysis of naturally acquired antibodies against these antigens in children would increase our knowledge about the development of protective immunity.Analysis of antibodies to Pf113, PfAMA1, PfEBA175, and PfRH5 was conducted in rural population during 2013 and 2014. Both prevalence and levels of total IgG anti-PfAMA1 were higher than that of IgG anti-PfEBA175, anti-PfRH5, and anti-Pf113. Seroconversion to PfAMA1 and PfEBA175 occurred moderately in young children and reached to the maximum in adolescent and in adults. High prevalence of IgG anti-Pf113 was observed in young children of 3 to 6 years old in 2013. The four antigens were recognized by IgG 1, 2, 3, and 4 antibodies from a large proportion of the subjects, and all of them induced high levels of specific IgG1 against PfAMA1, PfEBA175, fewer by Pf113 and PfRH5.Many asymptomatic children had specific IgG1 recognizing multiple antigens, and these IgG1 antibodies could be associated with a reduced risk of developing malaria symptoms.

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Background Malaria is the most deadly parasitic disease and continues to claim more than a half million of deaths across the world each year, mainly those of under-fives children in sub-Saharan Africa. The aim of this study was to determine the epidemiological, clinical and laboratory features of patients with severe malaria at the Centre Hospitalier Régional Amissa Bongo (CHRAB), a referral hospital in Franceville. Method It was an observational descriptive study conducted at CHRAB over ten months. All admitted patients at the emergency ward of all ages presenting with positive test to falciparum malaria diagnose by microscopy and rapid test with clinical signs of severe illness describe by World Health Organization were enrolled. Results During this study, 1065 patients were tested positive for malaria, of them 220 had severe malaria. Three quarters (75.0%) were younger than 5 years. The mean time to consultation was 3.5 ± 1 days. The most frequent signs of severity on admission were dominated by neurological disorders 92.27% in particular prostration 58.6% and convulsion 24.1%, followed by severe anemia 72.7% hyperlactatemia, 54.6%, jaundice 25% and respiratory distress 21.82%. The other forms such as hypoglycemia, haemoglobinuria, renal failure were found in low proportions <10%. Twenty-one patients died, coma (aOR = 15.54, CI = 5.43-44.41, p<0.01), hypoglycemia (aOR = 15.37, CI = 0.96-0.99, p<0.01), respiratory distress (aOR = 3.85, CI = 1.53-9.73, p=0.004) and abnormal bleeding (aOR = 16.42, CI = 3.57-104.73, p=0.003) were identified as independent predictors of a fatal outcome. Anemia was associated with decreased mortality. Conclusion Severe malaria remains a public health problem affecting mostly children under five years. Classification of malaria helps identify the most severely ill patients and aids early and appropriate management of the severe malaria cases.