Prevalence and pathology of Onchocerca infection in camels (Camelus dromedarius) in central parts of Iran

Background: Skin lesions of filarial worms are usually common in livestock. In camels, the most reported species is Onchocerca fasciata, which involves subcutaneous connective tissue and the nuchal ligament. OBJECTIVES: The aim of this study was to investigate the prevalence and pathology of camel onchocerciasis in Iran’s central desert. METHODS: Carcasses of 144 dromedary camels of both sexes and different ages, slaughtered at the slaughterhouse of three provinces in the central arid parts of Iran, were examined for  O. fasciata infection. In addition, the blood smears of tested animals were searched microscopically for the presence of microfilariae. RESULTS: The results of this study show that seventeen (11.8%) of the tested animals harbored one or multiple nodules containing the worm. Nodular lesions were mainly on the two sides of neck and abdomen. Histopathologically, multifocal granulomatous inflammatory reactions were observed to be associated with the parasites in the affected areas. Transverse and longitudinal sections of the worms were observed within the granulomas. The granulomas were composed of thick fibrous walls, the cellular infiltrate of lymphocytes, plasma cells, macrophages, multinucleated giant cells and eosinophils, associated with different degrees of coagulation necrosis and calcification around the parasites. No positive case was found in blood films. CONCLUSIONS: In this study, it was found that onchocerciasis is one of the relatively common skin lesions of camels in Iran. However, parasitemia is not common in the central partsof the country. Histopathologic changes in tissues are quite similar to granulomatous inflammations seen in other cutaneous infections.