Histoplasma seropositivity and environmental risk factors for exposure in a general population in Upper River Region, The Gambia: A cross-sectional study

Robust surveillance of Histoplasma species is warranted in endemic regions, including investigation of community-level transmission dynamics. This cross-sectional study explored anti- Histoplasma antibody seroprevalence and risk factors for exposure in a general population in Upper River Region (URR), The Gambia. Study participants were recruited (December 2022-March 2023) by random household sampling across 12 Enumeration Areas (EAs) of URR. A questionnaire and clinical examination were performed; exploring demographic, clinical and environmental risk factors for Histoplasma exposure. One venous blood sample per participant was subject to IMMY Latex Agglutination Histoplasma test to determine presence of a recent IgM response to Histoplasma. . Seropositivity risk factors were explored by multi-level, multivariable logistic regression analysis. The study population (n n = 298) aged 5-83 years, demonstrated a positively skewed age distribution and comprised 55.4% females. An apparent seroprevalence of 18.8% (n n = 56/298, 95% CI 14.5-23.7%) was measured using the LAT. A multivariable model demonstrated increased odds of Histoplasma seropositivity amongst female participants (OR = 2.41 95% CI 1.14-5.10); and participants reporting involvement in animal manure management (OR = 4.21 95% CI 1.38-12.90), and management of domestic animals inside the compound at night during the dry season (OR = 10.72 95% CI 2.02-56.83). Increasing age (OR = 0.96 95% CI 0.93-0.98) was associated with decreased odds of seropositivity. Clustering at EA level was responsible for 17.2% of seropositivity variance. The study indicates frequent recent Histoplasma exposure and presents plausible demographic and environmental risk factors for seropositivity. Histoplasma spp. characterisation at this human-animal-environment interface is warranted, to determine public health implications of environmental reservoirs in The Gambia. The study was supported by Wellcome Trust (206,638/Z/17/Z to CES) and a University of Liverpool-funded PhD studentship (to TRC).