Pre-Pandemic Cross-Reactive Immunity against SARS-CoV-2 among Central and West African Populations.

For more than two years after the emergence of COVID-19 (Coronavirus Disease-2019), significant regional differences in morbidity persist. These differences clearly show lower incidence rates in several regions of the African and Asian continents. The work reported here aimed to test the hypothesis of a pre-pandemic natural immunity acquired by some human populations in central and western Africa, which would, therefore, pose the hypothesis of an original antigenic sin with a virus antigenically close to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To identify such pre-existing immunity, sera samples collected before the emergence of COVID-19 were tested to detect the presence of IgG reacting antibodies against SARS-CoV-2 proteins of major significance. Sera samples from French blood donors collected before the pandemic served as a control. The results showed a statistically significant difference of antibodies prevalence between the collected samples in Africa and the control samples collected in France. Given the novelty of our results, our next step consists in highlighting neutralizing antibodies to evaluate their potential for pre-pandemic protective acquired immunity against SARS-CoV-2. In conclusion, our results suggest that, in the investigated African sub-regions, the tested populations could have been potentially and partially pre-exposed, before the COVID-19 pandemic, to the antigens of a yet non-identified Coronaviruses.

[HemoTypeSC screening for sickle cell disease in the Democratic Republic of Congo (DRC): a case from the city of Kindu]. / Dépistage hospitalier de la drépanocytose en République Démocratique du Congo (RDC) par HemoTypeSC: cas de la ville de Kindu.

Early detection of sickle cell disease is crucial to improve people's survival. Both financial and geographic accessibility to sickle cell disease tools are barriers to universal screening in developing countries. The purpose of this study was to determine the hospital prevalence of sickle cell disease and to assess the reliability of a rapid diagnostic tool, HemoTypeSC, in a resource-limited environment. We conducted a prospective cross-sectional descriptive study in the Department of Pediatrics of 5 health facilities in the city of Kindu, Maniema province, DRC, over a period of 10 months. The study consisted of HemoType SC rapid test screening for sickle cell disease and then diagnostic confirmation by hemoglobin electrophoresis. A total of 448 children less than 5 years of age were enrolled in the study. The overall hospital prevalence of patients with sickle cell disease was 31.9%, of whom 12.7% were homozygous (SS) and 19.2% trait carriers; the level of suspicion for sickle cell disease in hospitals was 6%; the clinical presumption regarding sickle cell disease was 8%; HemoType SC rapid test had good indicators of validity for the detection of hemoglobins A and S. The study shows that the hospital prevalence of major sickle cell disease is higher in children under 5 years of age with respect to clinical suspicion in the absence of laboratory tests. HemoTypeSC rapid test seems to be a reliable tool for the screening of the disease in the city of Kindu, a resource-limited environment.

Prevalence of Plasmodium falciparum parasites resistant to sulfadoxine/pyrimethamine in the Democratic Republic of the Congo: emergence of highly resistant pfdhfr/pfdhps alleles.

Background: In 2005, the Democratic Republic of the Congo (DRC) switched to artesunate/amodiaquine as the first-line antimalarial in response to increasing sulfadoxine/pyrimethamine resistance and adopted intermittent preventive treatment using sulfadoxine/pyrimethamine in pregnancy. Objectives: To determine the prevalence of molecular markers of sulfadoxine/pyrimethamine resistance in southwestern DRC 10 years after the new policy was instituted. Methods: From March 2014 to December 2015, blood samples were collected from symptomatic patients presenting to outpatient centres in urban and rural areas. A total of 2030 confirmed Plasmodium falciparum isolates were genotyped at codons associated with sulfadoxine/pyrimethamine resistance. Results: The prevalence of pfdhfr-N51I, C59R and S108N and pfdhps-A437G mutations was consistently high; the prevalence of the pfdhps-K540E mutation was low but increased since its first report in 2008 in the same region, reaching 17.6% by 2015. The pfdhps-A581G mutation increased from ∼4.5% in 2014 to ∼14.0% in 2015 at urban sites while in rural areas it remained low (∼4.0%). The mutations pfdhfr-I164L and pfdhps-A613S were detected for the first time in DRC. Also, 11 (0.8%) isolates revealed the presence of the newly described pfdhps-I431V mutation. Combining pfdhfr and pfdhps alleles, quintuple and sextuple mutations were observed, with the emergence of septuple (IRNI/IAGEGA)- and octuple (IRNI/VAGKGS)-mutant genotypes. Conclusions: Intermittent preventive treatment using sulfadoxine/pyrimethamine during pregnancy remains warranted in southwestern DRC. However, the expansion of pfdhps-K540E mutation and emergence of mutants that cause higher levels of sulfadoxine/pyrimethamine resistance is concerning and may present a challenge for future preventive interventions in the country.