Epidemiology, clinical characteristics, and transmission patterns of a novel Mpox (Monkeypox) outbreak in eastern Democratic Republic of the Congo (DRC): an observational, cross-sectional cohort study

Summary (abstract) Background In August 2023, an outbreak of mpox was reported in the eastern part, South Kivu Province, of Democratic Republic of the Congo. In this study, we aimed to investigate the origin of this outbreak and to assess how monkeypox virus spread among humans in the city of Kamituga. Methods We performed an observational cohort study by recruiting hospitalized patients with mpox-like symptoms. Furthermore, we compared structured, de-identified case report forms and interviews were conducted to determine the possible origins and modes of transmission of the mpox outbreak. We describe the clinical characteristics and epidemiology observed in reported infections. Findings During the study period (24 September 2023 to 29 January 2024), 164 patients were admitted to the Kamituga hospital, 51 individuals were enrolled in the study and interviewed, and 37 (73%) of 51 individuals received a molecularly confirmed mpox diagnosis. The median age for males was 24 years (IQR 18-30; range 14-36) and 19 years for females (IQR 17-21; range 1-59). The cohort was comprised of 47 (92%) of 51 individuals who identified as heterosexual, and two (4%) of 51 as bisexual, with 31 (61%) of 51 individuals sexually active with more than one partner within the last six months. The direct transmission routes are unknown; however, it is expected that the majority of infections were transmitted via occupational exposures. Out of the 51 individuals, 24 (47%) were professional sex workers (PSWs), while five (10%) were gold miners, 6 (12%) were students, and four (8%) were farmers; the remaining individual occupations were unknown. The most common symptoms associated with clinical mpox diagnosis were fever, which was described in 38 (75%) of 51 individuals, and rash, which was described in 45 (88%) of 51 individuals. Among those with a rash, 21 (41%) of 51 individuals experienced oral lesions, and 32 (63%) of 51 presented anogenital lesions. Mpox viral DNA was detected by qPCR from vaginal, penile, and oral swabs in 37 (73%) of 51 enrolled individuals. Two deaths were reported. Interpretation In this observational cohort study, mpox virus infection caused symptoms in a wide age range of participants with most cases presenting in sexually active individuals. Symptoms included fever, cough, lymphadenopathy, sore throat, chills, headache, back pain, muscle pain, vomiting, nausea, conjunctivitis, and rash (oral and anogenital). Heterosexual partners dominated human-to-human contact transmission suggesting that heterosexual close contact is the main form of transmission in this outbreak. Furthermore, Professional Sex Workers (PSWs) were the dominant occupation among infected individuals, indicating that PSWs and clients may be at higher risk for developing mpox virus infections.