Plague and the human flea, Tanzania

Domestic fl eas were collected in 12 villages in the western Usambara Mountains in Tanzania. Of these, 7 are considered villages with high plague frequency, where hu- man plague was recorded during at least 6 of the 17 plague seasons between 1986 and 2004. In the remaining 5 vil- lages with low plague frequency, plague was either rare or unrecorded. Pulex irritans, known as the human fl ea, was the predominant fl ea species (72.4%) in houses. The den- sity of P. irritans, but not of other domestic fl eas, was signifi - cantly higher in villages with a higher plague frequency or incidence. Moreover, the P. irritans index was strongly posi- tively correlated with plague frequency and with the logarith- mically transformed plague incidence. These observations suggest that in Lushoto District human fl eas may play a role in plague epidemiology. These fi ndings are of immediate public health relevance because they provide an indicator that can be surveyed to assess the risk for plague