Flea infestation of rodent and their community structure in frequent and non-frequent plague outbreak areas in Mbulu district, northern Tanzania

Abstract

Understanding rodent-ectoparasite interactions and the factors driving them is important in understanding the epidemiology of diseases involving an arthropod vector. Fleas are the primary vector for Yersinia pestis, the bacteria that causes plague and monitoring of flea population is essential for planning the potential mitigation measures to prevent the disease outbreak. In this study, we investigated flea abundance, community structure and the potential factors driving flea infestation in areas with frequent (persistent) and non-frequent plague (non-persistent) outbreaks. We collected fleas from captured rodents in two villages with both forest and farm habitats. We found 352 fleas belonging to 5 species with Dinopsyllus lypusus the most abundant overall (57.10%) and Ctenophthalmus spp. the lowest (1.70%). There were no significant differences of flea abundance between study localities, habitats and seasons (p > 0.05) but, flea infestation was significantly positively associated with the persistent locality and with the short rain season (p < 0.05). Further, flea abundance increased significantly with rodent body weight (p < 0.05). Furthermore, we found fleas broadly structured into two communities varying between the dry, long rain and short rain seasons. These findings have important implications for public health, as they may be used to assess and control the risks of plague transmission and other flea borne diseases in the foci.

Keywords: Flea abundance; Flea community; Flea-rodent interactions; Plague.

Graphical abstract

Fig. 1

A map of Mbulu district indicating the two study localities, Endeshi-Arri (Persistent locality and Mongahay (non-persistent locality), along with the two study habitats (Farmland and forests) in each locality.

Fig. 2

Flea abundance in the (a) localities, (b) habitats and (c) seasons. Error bars represent the standard error. There were no statistically significant differences that were observed.

Fig. 3

Flea abundance for different flea species across habitat types in each locality and rodent species.

Fig. 4

Plots showing predicted effect of rodent traits on flea abundance, based on final best fitting generalized linear mixed model with a negative-binomial function. The plots (a) indicates that rodent weight increased with flea abundance. The gray shade in the plots represents the strength and direction of the correlation, with the width of the shade indicating the 95% confidence interval (CI) around the estimated effect. Furthermore, plot (b) indicates that male rodents are more likely to have higher flea abundance compared to female rodents, but this association was not statistically significant. The bars are 95% confidence intervals of the effects.

Fig. 5

Plot showing the predicted effect of locality and season on the probability of flea infestation, based on the final best-fitting generalized linear model with a binomial function. The analysis aimed to identify the factors that strongly influence flea infestation. The strongest predictors of flea infestation were plague persistent localities and short rain seasons. The probability of infestation on these predictors was found to be statistically significant (p < 0.05), suggesting a higher likelihood of flea infestation in this locality and season. The bars are 95% confidence interval of the effects.

Fig. 6

Dendrogram of flea species showing two main groups (AB) of flea community based on farm and forest habitats.