Prior subclinical histoplasmosis revealed in Nigeria using histoplasmin skin testing

Disseminated histoplasmosis is an AIDS-defining illness. Histoplasmosis is commonly misdiagnosed as tuberculosis. Nigeria has the second highest number of people living with HIV/AIDS in Africa. The present study was carried out to investigate the prevalence of skin sensitivity amongst Nigerians to histoplasmin.

A cross-sectional study was conducted in six centres across five geopolitical zones of Nigeria.

We recruited both healthy non-HIV and HIV-positive adults with CD4 count ≥ 350 cells/mm3 regardless of their ART status from March to May 2017. Skin tests were performed intradermally; induration ≥5 mm were considered to be histoplasmin positive.

750 participants were recruited from Lagos (n = 52), Yola (n = 156), Ilorin (n = 125), Calabar (n = 120), Ibadan (n = 202) and Benin (n = 95). 467 (62.3%) were HIV negative, 247 (32.9%) were HIV positive and 36 (4.8%) did not know their HIV status. A total of 32/735 (4.4%) participants had a positive skin test. Study centre (p<0.001), education (p = 0.002) and age (p = 0.005) appeared to be significantly associated with positive skin reactivity at the 0.5% significance level, while sex (p = 0.031) and occupation (p = 0.031) would have been significant at the 5% significance level. Males had a higher rate of reactivity than females (p = 0.031, 7% vs 3%). The highest positive rates were recorded from Benin City (13/86 (15%)) and Calabar (7/120 (6%)) and no positives were recorded in Lagos (p<0.001). HIV status was not statistically significant (p = 0.70).

Histoplasmosis diagnostics should be included in the Nigerian HIV guidelines. Epidemiological vigilance of progressive disseminated histoplasmosis should be considered by local health authorities.