Monkeypox is an enzootic disease (prevalent in animals of a particular area) that circulates in monkeys in the rainforests of central and western Africa. It was previously believed that the virus is not easily transmitted to humans. However, 71 cases of monkeypox were recorded from February to August 1996, including six deaths that occurred in 13 villages, in Zaire. The virus causes a syndrome in humans clinically similar to smallpox. The symptoms are rashes, fever and respiratory trouble and it can sometimes lead to death.

The Zaire ministry of health and WHO ordered an investigation in February 1997 to assess the magnitude of the outbreak. Preliminary results of the investigation suggest that person-to-person transmission accounted for most monkeypox cases investigated in 1996 and 1997. In previous sporadic outbreaks, it was reported that it resulted from animal-to-human transmission.

Buffalopox is another disease similar to smallpox, though less dangerous since it mostly affects buffaloes. Occurrence of this disease has been reported from Punjab, Haryana, Maharashtra, Uttar Pradesh and Kerala. It was noticed in children in Beed district in Maharashtra by a team of scientists from the National Institute of Virology, Pune. The first outbreak of this infection was reported in buffaloes, cows and humans in Dhulia district, Maharashtra, in 1977.