Clinical and epidemiologic findings from enhanced monkeypox surveillance in Tshuapa Province, Democratic Republic of the Congo during 2011-2015.

BACKGROUND Monkeypox is a poorly described emerging zoonosis endemic to Central and Western Africa. METHODS Using surveillance data from Tshuapa Province, Democratic Republic of the Congo during 2011-2015, we evaluated differences in incidence, exposures, and clinical presentation of PCR-confirmed cases by sex and age. RESULTS We report 1,057 confirmed cases. Average annual incidence was 14·1 per 100,000 (95% CI: 13·3-15·0). Incidence was higher in males (incidence rate ratio [IRR] males: females: 1·21, 95% CI 1·07-1·37), except among 20-29-year-old (IRR: 0·70, 95% CI: 0·51-0·95). Females aged 20-29 years also reported a high frequency of exposures (26·2%) to people with monkeypox-like symptoms. Highest incidence was among 10-19-year-old males, the cohort reporting the highest proportion of animal exposures (37·5%). Incidence was lower among those presumed to have received smallpox vaccination versus those presumed unvaccinated. No differences were observed by age group in lesion count or lesion severity score. CONCLUSIONS Monkeypox incidence was twice that reported during 1980-1985, an increase possibly linked to declining immunity provided by smallpox vaccination. The high proportion of cases attributed to human exposures suggests changing exposure patterns. Cases were distributed across age and sex, suggesting frequent exposures that follow socio-cultural norms.