Hepatitis B and C Remain Hidden Threats Among Men Who Have Sex With Men in Kigali

Viral hepatitis has quietly become one of the most consequential infectious disease challenges in sub-Saharan Africa, and Rwanda has spent the past decade building one of the region’s more ambitious responses. Yet a persistent blind spot has shadowed that effort: reliable data on how hepatitis B and hepatitis C circulate among men who have sex with men and transgender women, populations that often sit outside routine surveillance. A new study published in BMC Infectious Diseases by Jean Olivier Twahirwa Rwema of Johns Hopkins Bloomberg School of Public Health and colleagues now provides some of the first rigorous estimates for Kigali, drawing on stored plasma samples from 729 participants recruited through respondent-driven sampling between March and August 2018.

The technical approach matters as much as the headline numbers. Rather than relying on self-reported diagnoses, which are notoriously unreliable in stigmatized populations, the researchers screened every sample with rapid diagnostic tests for hepatitis B surface antigen, the protein marker of active HBV infection, and for hepatitis C antibodies, which indicate past or present HCV exposure. Every positive result then underwent confirmatory viral load testing to distinguish active, replicating infection from resolved or false-positive serology. This two-stage design is essential because surface antigen positivity and detectable DNA carry very different clinical implications, from chronic infection requiring tenofovir-based therapy to the long-term risk of hepatocellular carcinoma.

The results paint a picture of moderate but non-trivial transmission. Hepatitis B surface antigen was detected in 25 of 729 participants, a crude prevalence of 3.4 percent that fell to 2.7 percent after adjustment for the respondent-driven sampling design, with a 95 percent confidence interval of 1.2 to 4.2 percent. Among those 25 surface-antigen-positive individuals, 92 percent had detectable HBV DNA, confirming active viral replication, with a median viral load of 3.0 log10 IU per milliliter. Hepatitis C antibody was found in 12 participants, or 1.6 percent crude prevalence, rising slightly to 1.7 percent when adjusted, and only a third of those antibody-positive samples, four of twelve, carried detectable HCV RNA.

That distinction between antibody positivity and detectable RNA is epidemiologically revealing. In settings where HCV transmission is driven primarily by injection drug use, most antibody-positive individuals remain viremic because the infection persists without treatment. The finding that two-thirds of antibody-positive participants in Kigali had no detectable RNA suggests a mixture of resolved infections and possibly past exposure through non-injection routes, though the small number of positive samples demands caution in interpretation. Still, the pattern hints that sexual transmission or other exposure pathways may contribute alongside any injection-related risk in this population.

To identify who was most at risk, the team used approximate Bayesian logistic regression with penalized likelihood estimation via data augmentation, a modeling strategy suited to sparse events and complex sampling designs. For hepatitis B, three factors emerged as independently associated with surface antigen positivity. Each additional year of age raised the odds by 4 percent, with an adjusted odds ratio of 1.04 and profile-likelihood limits of 1.00 to 1.09. Having sexual partners who had ever injected drugs more than tripled the odds, at an adjusted odds ratio of 3.13 with limits of 1.51 to 6.53. And reporting symptoms of a sexually transmitted infection in the year before enrollment roughly doubled the odds, at 2.11 with limits of 1.03 to 4.34. For hepatitis C, age was the only significant factor, with an adjusted odds ratio of 1.06 per year.

The age gradient deserves particular attention. When the authors stratified their data, prevalence among participants aged 35 and older reached 7.6 percent for hepatitis B surface antigen and 3.8 percent for hepatitis C antibodies, roughly two to three times the overall estimates. This older subgroup is one in which the same research team had previously documented higher burdens of HIV and other sexually transmitted infections, suggesting a convergence of infectious disease risks that accumulates over a lifetime of exposure. In practical terms, the men and transgender women most likely to harbor silent hepatitis infection are also those most likely to be engaged in HIV care, creating a natural opportunity for integrated screening.

The strong association between hepatitis B and partners who inject drugs carries perhaps the most programmatic weight. It implies that the sexual networks of MSM and transgender women who do not inject drugs overlap substantially with networks of people who do, allowing the virus to bridge between transmission routes that public health programs often address separately. Rwanda’s hepatitis programming, like much of the global response, has historically treated sexual and parenteral transmission as distinct problems requiring distinct services. The Kigali data argue that for these key populations, such silos are a liability, and that interventions should simultaneously address injection-related and sex-related acquisition risks.

Clinically, the stakes of missing chronic hepatitis B are considerable. Untreated chronic HBV infection is a leading cause of cirrhosis and hepatocellular carcinoma, and the authors explicitly frame ongoing screening as a way to strengthen not only prevention and treatment programs but also liver cancer surveillance. Rwanda has administered the pentavalent DTP-HepB-Hib vaccine in its childhood immunization schedule for years, which protects younger cohorts but does nothing for adults who were born before introduction or who were infected before vaccination. Tenofovir disoproxil fumarate and tenofovir alafenamide can suppress HBV replication effectively, while direct-acting antivirals now cure more than 95 percent of chronic hepatitis C cases, measured as sustained virological response at twelve weeks. None of these tools reach people who are never tested.

The study’s methodology also illustrates both the power and the limits of respondent-driven sampling. By having participants recruit peers from their own networks, RDS reaches populations that conventional sampling cannot, and the RDS adjustment attempts to correct for the non-random structure of those recruitment chains. But the approach cannot eliminate all bias, and the authors report sensitivity analyses examining how their Bayesian models performed under different assumptions about prior odds ratios. A further constraint is poignant: because contact information was not retained after the parent study concluded, the hepatitis test results could not be returned to the participants themselves, a limitation the ethics review at Emory University and the Rwanda National Research Ethics Committee weighed when approving the use of stored samples.

What emerges from Kigali is a call to action grounded in numbers rather than alarm. Hepatitis B and C are not exploding in this population, but they are present, active, and concentrated in identifiable subgroups: older MSM and transgender women, people reporting recent STI symptoms, and those connected to injection drug use networks. Rwanda’s experience with HIV, where key-population-focused services helped drive down incidence, offers a template. Embedding rapid hepatitis screening into existing HIV and STI services, extending vaccination and treatment to adults at risk, and designing outreach that acknowledges the overlap between sexual and injection networks would translate this study’s findings into measurable public health gain. As the authors conclude, tailored interventions for older MSM and transgender women are needed now, before silent infections convert into cirrhosis and cancer that screening could have prevented.

Subject of Research: Prevalence and risk factors of hepatitis B and C infection among men who have sex with men and transgender women in Kigali, Rwanda

Article Title: The prevalence of and factors associated with hepatitis B and hepatitis C among men who have sex with men in Kigali, Rwanda

Article References: The prevalence of and factors associated with hepatitis B and hepatitis C among men who have sex with men in Kigali, Rwanda. (n.d.). https://doi.org/10.1186/s12879-026-14498-7

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14498-7

Keywords: hepatitis B, hepatitis C, men who have sex with men, transgender women, Rwanda, Kigali, viral hepatitis, respondent-driven sampling, HBsAg, viral load, injection drug use, public health