Clinical and epidemiological observations on an outbreak of plague in Nepal.

In the autumn of 1967, plague broke out among hill people in western Nepal, a country that had not previously reported human plague. Two persons were infected from an active sylvatic focus at a grazing area 5 km from Nawra, the village where the epidemic occurred. The second patient introduced plague into the village where the rest of the cases occurred. Clinical and epidemiological evidence suggests that plague was spread both by the airborne route, resulting in 6 cases of tonsillar plague and 1 case of primary pneumonic plague, as well as by infected fleas, resulting in 17 cases of bubonic plague. Since no evidence of a rodent epizootic was uncovered in the village itself, and because of the distinct clustering of the bubonic cases, human-to-human spread of plague by infected ectoparasite vectors, presumably Pulex irritans, is thought to have occurred.This focus probably represents the most southerly boundary of the central Asian plague area yet identified.