Outbreak of Human Monkeypox, Democratic Republic of Congo, 1996 to 1997

TLDR

Human monkeypox is a zoonotic orthopoxvirus disease with limited interhuman transmissibility, and cessation of vaccinia vaccination after 1983 has increased the susceptible population. In February 1997, an outbreak of 88 cases (attack rate 22/1 000, case‑fatality 3.7 %) was identified in 12 villages of Katako‑Kombe, with 7 confirmed by virus isolation and serologic evidence of infection in 54 % of patients and 25 % of wild animals.

Abstract

Abstract Human monkeypox is a zoonotic smallpox-like disease caused by an orthopoxvirus of interhuman transmissibility too low to sustain spread in susceptible populations. In February 1997, 88 cases of febrile pustular rash were identified for the previous 12 months in 12 villages of the Katako-Kombe Health Zone, Democratic Republic of Congo (attack rate = 22 per 1,000, case-fatality rate = 3.7%). Seven were active cases confirmed by virus isolation. Orthopoxvirus-neutralizing antibodies were detected in 54% of 72 patients who provided serum and 25% of 59 wild-caught animals, mainly squirrels. Hemagglutination-inhibition assays and Western blotting detected antibodies in 68% and 73% of patients, respectively. Vaccinia vaccination, which protects against monkeypox, ceased by 1983 after global smallpox eradication, leading to an increase in the proportion of susceptible people.