Cutaneous distribution and localization of Cercopithifilaria sp. microfilariae in dogs

The aim of this study was to investigate the anatomical distribution of microfilariae of a recently described Cercopithifilaria sp. and the relationship with the preferred attachment sites of its vector, the brown dog tick Rhipicephalus sanguineus. Skin samples from 20 dogs were collected from eight anatomical sites and soaked twice in saline solution at 37 °C. All samples were also molecularly processed for the specific amplification of partial cytochrome c oxidase 1 gene. Microfilariae were unevenly distributed on the body, with higher frequencies on interscapular region (n = 13; 68.4%) and on the head (n = 9; 47.4%). Larval abundance in dogs was positively correlated with the number of positive anatomical sites with a higher percentage of skin samples scoring positive at the microscopic examination of the first sediment (n = 47; 30.9%) than of the second (n = 8; 5.3%). Histological examination revealed that microfilariae were scattered in the dermis, in association with inflammatory cells. Molecular analysis of skin samples showed a lower frequency of positive sites (n = 37; 24.3%) when compared to the microscopic examination (n = 53; 34.9%) with five haplotypes sequenced. The results here presented suggested a close co-evolution of this filarioid with its vector.