Species Composition, Diversity, Abundance, and Phylogeny of Fleas of Small Mammals in Selected Plague-Endemic and Nonendemic Areas of Tanzania.

The remerging nature of plague requires detailed understanding of the plague flea vectors and small mammal reservoir interactions. Therefore, this study is aimed at assessing flea vector composition, diversity, prevalence, abundance, and phylogeny in selected villages of Lushoto, Mbulu, and Morogoro Rural districts in Tanzania. Small mammals were captured from households and different habitats, and flea ectoparasites were collected, processed, and identified morphologically. Furthermore, seven specimens of the most collected flea species Ctenophthalmus sp. and Xenopsylla cheopis were submitted for advanced molecular identification and phylogenetic relatedness. The prevalence between predictors such as habitat type, host species, host sex, and locality was compared using chi-square tests, and also, generalized linear models (GLMs) were used to check the variation between flea abundance and different predictors. A total of 302 small mammals were captured with Mastomys natalensis (n = 163, 54.0%), Rattus rattus (n = 41, 13.6%), and Crocidura spp. (n = 31, 10.3%) dominating the total capture. The collected fleas belonged to nine species, and the most prevalent and abundant species were Ctenophthalmus spp. (n = 84, 31.0%), Pulex irritans (n = 82, 30.3%), Dinopsylla lypusus (n = 78, 28.8%), and Nosopsyllus incisus (n = 11, 4.1%) from rodents, and more so on males than females. The highest flea diversity was in crop fields (H' = 1.05) followed by near-natural forests (H' = 1.03) and fallow land (H' = 0.7). Phylogenetic analysis of ITS1 sequences for Ctenophthalmus sp. and Xenopsylla cheopis from Lushoto and Mbulu districts showed strong nucleotide identity. These findings highlight the need for continuous flea and rodent surveillance to mitigate potential plague outbreaks and protect public health in endemic areas.