A genetic perspective on the taxonomy and evolution of the medically important flea,Dinopsyllus ellobius (Siphonaptera: Dinopsyllinae), and the resurrection of Dinopsyllus abaris

Dinopsyllus ellobius is considered a common and widespread flea in southern Africa and can act as a vector for plague. Due to differences in the interpretation of geographical variation in male sternite VIII, the taxonomy of the species is characterized by uncertainty. In an attempt to provide a better understanding of the systematics of D. ellobius, and also to provide new insights into the mechanisms that play a role in the diversification of the taxon, we sampled 830 small mammals at 31 localities throughout the distribution range of the parasite. Mitochondrial cytochrome c oxidase subunit II (COII) sequence data were generated for 151 D. ellobius specimens from 19 positive localities and this data set was supplemented with partial data derived from an elongation factor 1 alpha (EF1‐α) intron. A parsimony haplotype network of the mtDNA and a Splitstree analyses revealed the existence of two genetic clades that were separated by 5.53% (± 1.78) sequence divergence. Although the nuclear DNA data were unresolved, significant size differences were detected between head, coxa, femur and tibia lengths of male individuals belonging to the two mtDNA lineages. The exact mechanisms that could have caused the diversification among lineages are not clear but the two lineages seem to be geographically separated and may have different ecological requirements. The present study strongly supports the notion that the two lineages are representative of D. ellobius (probably more associated with the host body and better adapted to mesic conditions) and Dinopsyllus abaris (probably more associated with the host nest and diverse climatic conditions) as originally proposed based on the single morphological character confined to male sternite VIII.     

Seasonal patterns of rodents, fleas and plague status in the Western Usambara Mountains, Tanzania

Field and commensal rodents were live-trapped at three villages in an active focus of plague (Yersinia pseudotuberculosis pestis) in Lushoto District, Western Usambara Mountains, Tanga Region, Tanzania, from December 1983 to November 1984. Their flea ectoparasites were collected, identified and counted. The rodent carcasses were serologically examined for specific plague antibodies and antigens, and bacteriologically examined for bipolar staining bacilli. A total of 1758 traps were set during the 12-month period and 924 animals were caught. From these, 1037 fleas were collected. Rattus rattus (L.), Praomys natalensis (Smith) and Lophuromys flavopunctatus Thomas comprised the largest proportions of the rodent population, while Dinopsyllus lypusus Jordan & Rothschild, Ctenophthalmus calceatus Waterston and Xenopsylla brasiliensis (Baker) were the dominant flea species. Rodents were most abundantly trapped during December and January. Flea indices were highest from December to May. Human plague was most active from November to March. Rodents contained plague antibodies every month except May and July, with a peak in September. Plague antigens and bipolar bacilli were detected in rodent organs during January-April. From the product of abundance and infection rate, the most prevalent rodent hosts of plague appeared to be R. rattus, Otomys angoniensis Wroughton, P. natalensis and Pelomys fallax (Peters). Continuous integrated control of rodents and fleas was recommended, reinforced by quarantine and maintenance of a surveillance service for clinical detection, diagnosis and treatment of patients in the plague endemic area.