HIV Self-Tests Flag High Reactivity Among Key Populations in Cameroon’s Largest Cities

A large community-based study in Cameroon has revealed a strikingly high burden of presumed HIV infection among two of the country’s most marginalised populations, with nearly one in four participants producing a reactive result on a blood-based HIV self-test. The research, conducted in Yaoundé and Douala between November 2021 and July 2022, offers some of the most detailed evidence yet on where and among whom the virus is concentrated in these urban centres, and it points to sharp geographic and educational divides that could reshape prevention efforts.

HIV self-testing has become a cornerstone strategy for reaching people who face barriers to conventional clinic-based services. In Cameroon, both same-sex practices and sex work are criminalised, and the resulting stigma and fear of disclosure deter many men who have sex with men and female sex workers from visiting health facilities for testing. Self-testing sidesteps that obstacle: participants collect a small blood sample themselves, apply it to a rapid diagnostic strip, and read the result privately. Crucially, the test functions as a triage tool rather than a definitive diagnosis, meaning any reactive result must be confirmed through standard laboratory algorithms before treatment can begin.

The study enrolled 789 participants through 17 community-based organisations, ten serving men who have sex with men and seven serving female sex workers, in the two largest cities. All participants were aged 21 or older and were recruited through voluntary sampling. After counselling, each person performed an unassisted self-test and completed a structured questionnaire covering demographic characteristics, sexual behaviour, and medical history. The researchers then used modified Poisson regression, a statistical approach suited to common outcomes in cross-sectional data, to calculate adjusted prevalence ratios that quantify how each factor relates to the probability of a reactive test while controlling for other variables.

The headline finding is sobering: 23.3 percent of all participants had a reactive self-test, with a 95 percent confidence interval of 20.5 to 26.4 percent. The proportions were nearly identical across the two populations, at 23.2 percent among female sex workers and 23.4 percent among men who have sex with men, suggesting that both groups carry a comparably heavy and previously underappreciated burden of presumed infection. Because reactive self-tests require confirmatory testing, these figures represent an upper signal of infection prevalence rather than confirmed diagnoses, but the sheer scale of reactivity underscores how much undiagnosed infection may be circulating within networks that clinics rarely reach.

Perhaps the most dramatic signal in the data is geographic. Reactivity was more than three times higher in Yaoundé, the capital, than in Douala, the country’s economic hub, at 38.3 percent versus 12.2 percent. After statistical adjustment, living in Douala was associated with a 78 percent lower probability of reactivity among female sex workers and a 69 percent lower probability among men who have sex with men. This concentration in a single city is epidemiologically significant because it implies that tailored interventions, from intensified testing campaigns to partner services and pre-exposure prophylaxis roll-out, could achieve disproportionate impact if prioritised in Yaoundé rather than spread evenly across both metropolises.

Education emerged as a powerful and consistent protective correlate, particularly among women. Relative to female sex workers with no formal schooling, those with primary education had a 72 percent lower adjusted probability of a reactive test, those with secondary education a 66 percent lower probability, and those with higher education a 56 percent lower probability. A similar gradient appeared among men who have sex with men, where secondary education was associated with a 63 percent reduction. The pattern likely reflects the ways literacy and schooling shape access to health information, negotiating power in commercial sex, economic alternatives, and familiarity with preventive technologies, though the cross-sectional design cannot disentangle the underlying mechanisms.

Behavioural and clinical history markers also carried important signals. Among female sex workers, a history of symptoms suggestive of sexually transmitted infections nearly tripled the adjusted probability of reactivity, tripling the odds relative to women without such a history. This finding aligns with well-established virology: genital ulceration and inflammation amplify both acquisition and transmission of HIV by recruiting activated CD4-bearing target cells to mucosal surfaces and disrupting epithelial barriers. It also suggests that syndromic STI screening, when integrated with self-testing programmes, could serve as an efficient triage layer identifying women at highest risk.

Among men who have sex with men, each additional sexual partner over the preceding six months was associated with a modest but statistically reliable 3 percent increase in the probability of reactivity, a dose-response relationship consistent with cumulative exposure risk. Interestingly, alcohol consumption was associated with a 35 percent lower adjusted probability of reactivity in this group. The authors caution that such counterintuitive associations in cross-sectional data may reflect residual confounding or complex social patterns rather than any protective biological effect of alcohol itself.

The methodological strength of the study lies in its scale, its reliance on trained community-based organisations to recruit criminalised populations that formal health systems typically miss, and its use of regression techniques appropriate for high-prevalence outcomes. The ethical scaffolding was equally careful: the protocol received approval from Cameroon’s National Ethics Committee for Human Health Research and administrative authorisation from the Ministry of Health, and every participant provided written informed consent, with data handled confidentially given the acute legal risks these populations face.

The implications for public health strategy are direct. The authors conclude that reactive self-tests were frequent among both populations, with a marked concentration in Yaoundé and among unschooled female sex workers, and they argue that geographically prioritised, differentiated prevention, combined with STI screening and robust linkage to confirmatory testing, would meaningfully reduce this burden. As Cameroon and its regional neighbours work toward UNAIDS testing and treatment targets, the study demonstrates that self-testing is not merely a convenience but a surveillance instrument, capable of mapping where infection concentrates and guiding resources to the people and places that need them most.

Subject of Research: Factors associated with reactive HIV self-test results among female sex workers and men who have sex with men in Cameroon

Article Title: Factors associated with a reactive HIV blood self-test result among female sex workers and men who have sex with men in Yaoundé and Douala, Cameroon: a cross-sectional study

Article References: Ndié, J., Noah, J.-P. Y. A., Ndongo, F. A., Dongmo, R. K., Yongwa, O., Tchikangni, G., Palisson, T. A. N., Ketchaji, A., Yepndo, C. D., Ndindjock, C. B., IV, Tabala, F. N., Bonyohe, M., Moulioum, F., Nzaddi, A. R. D., Monteh, C. T., Mboussam, P. H., Nguemkam, G., Seukam, B., Anaba, E. D. M., … Bissek, A. C. Z.-K. (2026). Factors associated with a reactive HIV blood self-test result among female sex workers and men who have sex with men in Yaoundé and Douala, Cameroon: a cross-sectional study. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14598-4

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14598-4

Keywords: HIV self-testing, HIV, Cameroon, men who have sex with men, female sex workers, key populations, prevalence, Yaoundé, Douala, sexually transmitted infections, public health, cross-sectional study