Outbreak of human monkeypox, Democratic Republic of Congo, 1996-1997

Human monkeypox is a zoonotic smallpox-like disease caused by an orthopoxvi rus of interhuman transmissibility too low to sustain spread in susceptible populations. In February 1997, 88 cases of febrile pustular rash were iden tified 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-fatal ity rate = 3.7%). Seven were active cases confirmed by virus isolation. Ort hopoxvirus-neutralizing antibodies were detected in 54% of 72 patients who provided serum and 25% of 59 wild-caught animals, mainly squirrels. Hemaggl utination-inhibition assays and Western blotting detected antibodies in 68% and 73% of patients, respectively. Vaccinia vaccination, which protects ag ainst monkeypox, ceased by 1983 after global smallpox eradication, leading to an increase in the proportion of susceptible people.