Abstract
This paper reports the occurrence for the first time in Italy of autochthonous Onchocerca infection in donkeys. Four jennies, bred on the same farm, were referred to the Veterinary Teaching Hospital of Pisa for a check-up on ovarian activity (n = 3) or for veterinary support during the delivery (n = 1). Microfilariae were incidentally detected during the blood smear examination of one jenny. Peripheral blood samples were then collected from the other three jennies and the presence of microfilariae was investigated by Knott's test. Circulating unsheathed microfilariae were identified in all the animals. The level of microfilaraemia was between 1 and 31 microfilariae in 2 mL of blood. Hematological changes showed moderate eosinophilia in one case or both remarkable eosinophilia and basophilia in another case. Based on molecular findings by PCR and sequencing, the microfilariae showed 98% sequence similarity with Onchocerca sp. in the NCBI GenBank database (Accession No.: MK541848.1). The present report provides evidence that Onchocerca is an etiological agent of parasitic infection in donkeys in Italy. Our findings highlight the importance of screening in donkeys for Onchocerca even in the absence of clinical indications.
Highlights
Onchocerca cervicalis, Onchocerca reticulata, and Onchocerca raillieti (Onchocercidae, Spirurida) are filarial thread-like nematodes
Eosinophilia was found in both animals and in jenny III it was substantial as was the occurrence of basophilia
The concentration of microfilariae that we found in the peripheral blood samples is likely to be much lower than the actual microfilariae concentration in the tissues of the examined jennies because Knott’s test is not the most suitable method to detect microfilariae in Onchocerca infected equids
Summary
Onchocerca cervicalis, Onchocerca reticulata, and Onchocerca raillieti (Onchocercidae, Spirurida) are filarial thread-like nematodes. O. raillietti has only been reported in donkeys in Africa [1] and adult worms live in the ligamentum nuchae [3]. Adult females release microfilariae (L1) measuring 190–310 μm for O. cervicalis, 330–370 μm for O. reticulata [4], and 180–217 μm for O. raillieti [3]. Information is only available for the life cycle of O. cervicalis [4], the transmission pathways of O. cervicalis, O. reticulata, and O. raillieti are likely to be similar. These parasites are all transmitted by blood-sucking midges of Culicoides
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