Lymph nodes of red deer infected with subcutaneous filariae Wehrdikmansia cervipedis (Wehr et Dikmans, 1935) and Onchocerca flexuosa (Wedl, 1856)

First molecular detection of Onchocerca flexuosa (Wedl, 1856) in red deer in Slovakia

The present paper deals with the post-mortem diagnostics of onchocerciasis and the molecular detection of causative agents of this disease in wild ruminant ungulates (Cervus elaphus, Dama dama and Capreolus capreolus). The animals were shot in hunting seasons 2017 and 2018, in two regions of the Eastern Slovakia. The total number of examined skins was fifty-eight. The presence of subcutaneous nodules was confirmed in 27.59% (95% CI 16-39) of animals. All positive skins belonged to red deer individuals (47.06%; 95% CI 30-64). The nodules were present mainly in the back area and in the lumbar area, and their sizes ranged from 2.9 to 24.1 mm, with the average count of 10 nodules per animal. Thirteen worms, isolated from the nodules collected from 13 animals, were subjected to molecular identification. Applying the standard PCR method, targeting the mitochondrial 12S rRNA, 16S rRNA and NADH-dehydrogenase gene, and subsequent sequencing, all the worms were identified as Onchocerca flexuosa Wedl, 1856. The sequences were submitted to GenBank under specific accession numbers. Two samples were identified as Onchocerca flexuosa haplotype B, in which T176A and A177T were present. Despite the presence of mutations in the 12S rRNA of the Onchocerca flexuosa, the standardized PCR remains to be a very specific and sensitive method that uses this fragment as a selectable marker for the detection of the studied parasite.

First description of Onchocerca jakutensis (Nematoda: Filarioidea) in red deer (Cervus elaphus) in Switzerland

Twenty-seven species of the genus Onchocerca (Nematoda; Filarioidea) can cause a vector-borne parasitic disease called onchocercosis. Most Onchocerca species infect wild and domestic ungulates or the dog, and one species causes river blindness in humans mainly in tropical Africa. The European red deer (Cervus e. elaphus) is host to four species, which are transmitted by blackflies (simuliids) or biting midges (ceratopogonids). Two species, Onchocerca flexuosa and Onchocerca jakutensis, produce subcutaneous nodules, whereas Onchocerca skrjabini and Onchocerca garmsi live free in the hypodermal serous membranes. During the hunting season, September 2013, red deer (n = 25), roe deer (Capreolus c. capreolus, n = 6) and chamois (Rupicapra r. rupicapra, n = 7), all shot in the Grisons Region (Switzerland) were investigated for the presence of subcutaneous nodules which were enzymatically digested, and the contained Onchocerca worms were identified to species by light and scanning electron microscopy as well as by PCR/sequencing. In addition, microfilariae from skin samples were collected and genetically characterized. Neither nodules nor microfilariae were discovered in the roe deer and chamois. Adult worms were found in 24% of red deer, and all of them were identified as O. jakutensis. Two morphologically different microfilariae were obtained from five red deer, and genetic analysis of a skin sample of one red deer indicated the presence of another Onchocerca species. This is the first report of O. jakutensis in Switzerland with a prevalence in red deer similar to that in neighbouring Germany.