Mpox (monkeypox) risk and mortality associated with HIV infection: a national case-control study in Nigeria

Recent outbreaks of mpox are characterised by changes in the natural history of the disease, the demographic and clinical characteristics of the cases, and widening geographical distribution. We investigated the role of HIV and other sexually transmitted infections (STIs) coinfection among cases in the re-emergence of mpox to inform national and global response.

We conducted a national descriptive and case-control study on cases in the 2017-2019 Nigerian mpox outbreak. Mpox cases were age, sex and geographical area matched each with two randomly selected controls from a representative national HIV/AIDS survey. Logistic regression was used to investigate the association between HIV infection and the risk of mpox acquisition and death.

Among 204 suspected mpox cases, 86 were confirmed (median age 31 years (IQR 27-38 years), mostly males (61 cases, 70.9%). Three-fifths of mpox cases had serological evidence of one or more STIs with 27.9% (24/86) coinfected with HIV. The case fatality rate was 9.4% (8/86) and 20.8% (5/24) overall and in HIV positive cases respectively. Mpox cases were more likely to have HIV coinfection compared with an age, gender and geography-matched control group drawn from the general population (OR 45 (95% CI 6.1 to 333.5, p=0.002) and when compared with non mpox rash cases (7.29 (95% CI 2.6 to 20.5, p<0.0001)). HIV coinfection and young age were associated with mortality among mpox cases (aOR 13.66 (95% CI 1.88 to 98.95, p=0.010) and aOR 0.90 (0.82-0.97, p=0.008), respectively).

HIV infection was associated with a higher risk of contracting and dying from mpox. Children are also at high risk of death. STIs in mpox cases may be suggestive of high-risk sexual behaviours among these individuals.