Prevalence of Rickettsia typhi in rodent fleas from areas with and without previous history of plague in Mbulu district, Tanzania

Murine (endemic) typhus is a flea-borne infectious disease caused by Rickettsia typhi. The disease transmission cycle has similarities to that of Yersinia pestis causing plague. It is hypothesized that murine typhus is prevalent in areas with plague transmission. This study aims at detection of R. typhi in rodent fleas by conventional polymerase chain reaction (PCR). A cross sectional study was carried out in Mbulu district in villages with, and without previous history of plague from November 2018 to February 2019. Sherman® traps were set in forest and agricultural habitats while box traps were set inside houses. Captured rodents were anaesthetized using halothane and fleas were removed from the fur using a hard brush and preserved in 70% ethanol. PCR amplification of the targeted citrate synthase (gltA) gene of R. typhi was done using primers RpCS.877p and RpCS.1258n. 12 (24%) of the DNA from rodent fleas was positive for R. typhi. Of these, 5 (10%) and 2 (4%) were from farms and forests with previous plague history respectively, while 3 (6%) and 2 (4%) were from houses and farms with no previous plague history, respectively. This suggests the prevalence of murine typhus is independent of plague infections.