Genetic and morphological characterization of Thysaniezia tapeworms from cattle and sheep in Senegal

Genetic and morphological diversity of Thysaniezia tapeworms from cattle and sheep in Senegal was investigated using light and scanning microscopic observations and molecular analysis based on mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear small subunit ribosomal RNA gene (SSU rDNA). A total of 52 adult tapeworms were collected from sheep and cattle. Although the tapeworms of the two hosts were morphologically very close, phylogenetic analysis based on cox1 and SSU rDNA gene sequences showed that they were divided into two clades corresponding each to a host. The maximum pairwise divergence between the clades were 12.1% in cox1 and 2.9% in SSU rDNA, indicating they are distinct species. The tapeworms collected from sheep were morphologically identified as Thysaniezia ovilla, a cosmopolitan species in domestic ruminants. Detailed morphological observations revealed a consistent difference between the tapeworms obtained from sheep and those from cattle. The latter were identified as Thysaniezia connochaeti. The present study highlights presence of two species of Thysaniezia among domestic ruminants in Senegal: T. ovilla specific to sheep and T. connochaeti specific to cattle. Our work is the first report of T. connochaeti from domestic animals.