Cysticercosis by Taenia pisiformis in Brown Hare (Lepus europaeus) in Northern Italy: Epidemiologic and pathologic features

In Northern Italy, a hastening of hare population decline was noticeable from 2008. In the same year hunters reported a sudden increase of hares infected by Taenia sp. larvae, whose morphology was consistent with T. pisiformis cysticerci. The aim of the survey was: i)to identify the parasites through morphological features and molecular techniques; ii)to quantify the prevalence and abundance of cysticerci in hunted hares; iii)to describe pathological aspects of parasite-induced lesions; iv)to evaluate the short-term trend of the infection comparing two different hunting seasons; v)to highlight possible relationship between T. pisiformis infection and hare-related variables. In 2013, 2015 the viscera of 54 and 61 hares legally hunted in agro-ecosystems of the Po Plain were collected. Peritoneum, liver and lungs were examined for cysticercosis; abundance was estimated counting superficial parasites in liver; parasites were microscopically identified by shape and measure of both large and small hooks. One cysticercus from each hare was analized by a PCR targeting Taeniid species and then sequenced. Frozen liver, lungs and gastrointestinal peritoneum were macroscopically observed and, after thawing, representative samples from the available organs were collected for histologic examination to verify parasitic cysts and the subsequent damage of the involved organs. Sex, weight and age class of the animals were recorded. Generalized linear models were used for statistical analysis. T. pisiformis was isolated in 8 hares in 2013 (prevalence 14.8%; abundance range: 0-400; mean abundance 17.8) and in 2 hares in 2015 (prevalence 3.28%; abundance range: 0-180; mean abundance 3.22). Identification was confirmed morphologically and by PCR. The DNA sequencing confirmed T. pisiformis in all samples. The sequences were all identical each-other. Infection was significantly related with adult age class, sampling year and low full-weight. Epidemiological and pathological pattern suggest both a possible role on host population health and a tendency toward host-parasite equilibrium.