3 research outputs found
Determinants of long-term SARS-CoV-2 immune responses in asymptomatic-to-moderate COVID-19 patients in sub-Saharan Africa
No full textAbstract Background Immune responses after SARS-CoV-2 infection remain poorly characterized in African populations, despite widespread viral transmission and proportionally lower COVID-19 severity and mortality than in other regions. We aimed to define the determinants and durability of humoral and cellular immunity in sub-Saharan Africa and to identify immune correlates of protection against reinfection. Methods We conducted a 12-month longitudinal immunological study involving 513 adults with asymptomatic or mild-to-moderate COVID-19 enrolled across four sub-Saharan African countries (Ghana, Democratic Republic of Congo, Ethiopia, and Mozambique) during four pandemic waves (2020–2022). We profiled levels of IgA, IgG, and IgM against eight SARS-CoV-2 antigens and neutralizing antibody activity against ancestral and variant strains by Luminex, and antigen-specific T- and B–cell responses by flow cytometry. Immune kinetics, decay, immune escape, and reinfection risk were evaluated alongside the impact of clinical and demographic variables, including prior exposure, epidemic wave, geographic site, treatment allocation, and host factors. Statistical analyses included non-parametric tests (Kruskal–Wallis with Benjamini–Hochberg adjustment), Spearman correlations, logistic regression for reinfection, and mixed-effects models for longitudinal determinants. Results Humoral and cellular immune responses were robust and sustained across participants. Estimated antibody half-lives during the early decay phase exceeded 50 days for IgA and IgG. Higher IgA, IgG, and neutralizing levels were significantly associated with lower odds of reinfection during follow-up. Repurposed COVID-19 treatments showed no measurable impact on immune responses. Prior infection and vaccination were the main determinants of antibody magnitude and persistence, greatly surpassing the effects of age, sex, symptoms, and comorbidities. Antibody levels also varied significantly by epidemic wave and site, higher in later waves and, across sites, generally higher in Ethiopia and lower in DRC. Comorbidities were primarily associated with increased SARS-CoV-2–specific T-cell activation. Strong correlations were observed between binding and neutralizing antibodies, and variant-specific immune escape was confirmed for Beta, Gamma, and Omicron. Conclusions This multi-country study provides a comprehensive characterization of SARS-CoV-2 humoral and cellular immune responses in African cohorts and identifies prior exposure and local epidemiological context as the main determinants of immune magnitude, durability, and protection, outweighing other host factors
Outbreak of cutaneous leishmaniasis amongst militia members in a non-endemic district under conflict in the lowlands of Somali Region caused by Leishmania tropica, Eastern Ethiopia.
No full textBackgroundCutaneous leishmaniasis (CL) in Ethiopia has typically been linked to high-altitude regions but has recently emerged at an unusually low altitude of 500 meters in the Somali Region, raising public health concerns. Cutaneous leishmaniasis has not been previously identified in the region. There is a conflict in the starting area and only militias have been infected with very serious lesions.Methodology/principal findingsRoutine clinical and socio-demographic information was extracted from the patient chart using a case report form. Additionally, clinical and laboratory data were obtained from 30 patients suspected for CL. Skin scraping and fine needle aspirates were collected from the raised edges, nodular and centre of the lesions followed by DNA extraction using the DNeasy Blood and Tissue kit. There were a total of 1050 CL patients recruited, all of them were male militia members, immunologically naïve and displaced into a conflict area with a likely sylvatic transmission cycle. We identified Leishmania tropica as the causative species, challenging the previous assumption that L. aethiopica was the primary agent of CL in Ethiopia. Notably, over 77% of patients had more than 10 lesions, a presentation atypical for L. tropica elsewhere. Phlebotomus orientalis and P. sergenti, vectors for visceral leishmaniasis and CL in North Africa respectively, were found in the outbreak area.Conclusions/significanceFurther research is needed to explore the eco-epidemiology of the outbreak and patient's treatment responses. Insights will help develop management strategies to control this newly emerging form of CL, prevent its spread to other regions and hybridization with Leishmania strains causing VL endemic in the area
