The relationship of field rodents to plague in Kenya

Abstract

1. A study of the literature of East Africa on the incidence of plague in field rodents shows that in no single instance has evidence been offered to prove they have any relation to the disease.2. Recent epizootics in field rats in Kenya are described.3. The health of house and field rats is discussed, with an account of the work carried out on a septicaemic condition present in field rats.4. The results of bacteriological examination of 2750 field rats and attempted transmission experiments with 1285 field fleas, both investigations conducted during a period when there was heavy mortality among them, failed to establish the presence of B. pestis.At the same time, mortality among the Rattus population, proved bacteriologically to have been caused by B. pestis, enabled successful transmissions to be accomplished with fleas from that species.5. In the absence of any confirmatory bacteriological evidence to prove that epizootics among field rats are caused by B. pestis, and the failure to find natural infection among field fleas, together with the knowledge of their aversion to feed on man and lack of opportunity to develop such tastes, the theories that field rodents and their fleas “are definitely assisting in the perpetuation and spread of plague” or that they “ are possible factors in initial outbreaks of plague” (Thornton, 1930) appear to be fallacious.6. Plague in Kenya is distinguished by its isolated and sporadic nature, even in endemic areas, and it is not dependent on types of housing or the general hygiene of inhabited areas, but on individual domestic habits. Any individual, neglectful in regard to food, particularly its storage and wastage, is the person responsible for the disease, by offering an unlimited supply of food to a dense rat population and encouraging its survival.