Clinical characteristics and predictors of human mpox outcome during the 2022 outbreak in Nigeria: a cohort study

Abstract

Background: Research from sub-Saharan Africa that contributes to our understanding of the 2022 mpox (formerly known as monkeypox) global outbreak is insufficient. Here, we describe the clinical presentation and predictors of severe disease among patients with mpox diagnosed between Feb 1, 2022, and Jan 30, 2023 in Nigeria.

Methods: We did a cohort study among laboratory-confirmed and probable mpox cases seen in 22 mpox-treatment centres and outpatient clinics across Nigeria. All individuals with confirmed and probable mpox were eligible for inclusion. Exclusion criteria were individuals who could not be examined for clinical characterisation and those who had unknown mortality outcomes. Skin lesion swabs or crust samples were collected from each patient for mpox diagnosis by PCR. A structured questionnaire was used to document sociodemographic and clinical data, including HIV status, complications, and treatment outcomes from the time of diagnosis to discharge or death. Severe disease was defined as mpox associated with death or with a life-threatening complication. Two logistic regression models were used to identify clinical characteristics associated with severe disease and potential risk factors for severe disease. The primary outcome was the clinical characteristics of mpox and disease severity.

Findings: We enrolled 160 people with mpox from 22 states in Nigeria, including 134 (84%) adults, 114 (71%) males, 46 (29%) females, and 25 (16%) people with HIV. Of the 160 patients, distinct febrile prodrome (n=94, 59%), rash count greater than 250 (90, 56%), concomitant varicella zoster virus infection (n=48, 30%), and hospital admission (n=70, 48%) were observed. Nine (6%) of the 160 patients died, including seven (78%) deaths attributable to sepsis. The clinical features independently associated with severe disease were a rash count greater than 10 000 (adjusted odds ratio 26·1, 95% CI 5·2-135·0, p<0·0001) and confluent or semi-confluent rash (6·7, 95% CI 1·9-23·9). Independent risk factors for severe disease were concomitant varicella zoster virus infection (3·6, 95% CI 1·1-11·5) and advanced HIV disease (35·9, 95% CI 4·1-252·9).

Interpretation: During the 2022 global outbreak, mpox in Nigeria was more severe among those with advanced HIV disease and concomitant varicella zoster virus infection. Proactive screening, management of co-infections, the integration and strengthening of mpox and HIV surveillance, and preventive and treatment services should be prioritised in Nigeria and across Africa.

Funding: None.