EPIDEMIOLOGY AND DISTRIBUTION OF PARASITES OF ANIMAL - SPECIFIC AND ZOONOTIC IMPORTANCE IN PIG FARMS IN NORTHERN ITALY.

In Italy pig production is traditionally based on intensive farming systems, predominantly confined indoors. In this context, parasitic diseases may often present a subclinical pattern resulting in less attention paid to them by farmers and veterinarians. Although oligosymptomatic trends predominate, parasites may be responsible for decreased animal welfare and significant economic losses due to reduced weight gain, increased feed consumption and organ condemnation during the post-mortem inspection at the abattoir. Furthermore, parasitic infections are often underdiagnosed and their role in intestinal disorders is seldom considered in differential diagnoses. An additional concern is the zoonotic potential of several pig parasites, which can pose health risks to individuals working along the food production chain, from farm personnel to abattoir workers. Control measures should be focused on both eliminating parasites from the host and reducing their survival and persistence in the environment. Given the growing concern about the anthelmintic resistance, an effective approach requires an integrated strategy that combines pharmacological interventions with optimized management practices. The review of the scientific literature revealed several gaps in the epidemiology of parasites in Italian pig farming. Thus, the main aims of this research project, structured into specific research lines, were: 1. To update epidemiological data on parasite prevalence For the first research line, 22 intensive fattening pig farms were recruited, and a total of 880 fecal samples were collected in two different sampling sessions to assess the circulation of gastrointestinal parasites throughout the fattening cycle. Moreover, a longitudinal study was carried out in one of the largest national abattoirs to determine the prevalence of milk spot lesions, indicative of Ascaris suum larval migration, in the livers of slaughtered pigs from 399 fattening farms. Finally, a serological analysis was conducted in 23 intensive pig farms to detect antibodies against the mite Sarcoptes scabiei, the causative agent of sarcoptic mange. Copromicroscopic analysis revealed that 95 out of 880 samples (10.8%) were positive for at least one parasitic taxon, with 63.6% (14/22) of the surveyed farms testing positive. Notably, farm management factors, such as the application of the all-in/all-out system and farm size, were significantly associated with parasite prevalence. These findings emphasize the need for targeted control strategies, including standardized anthelmintic protocols and regular fecal monitoring. Milk spot lesions were observed in 92.2% of the investigated farms and 26.4% of slaughtered pigs. Breeding province and season of post-mortem inspection emerged as significant risk factors. The high prevalence recorded underscores the importance of improving communication between abattoirs, veterinarians, and farmers to enhance animal health surveillance and control A. suum circulation. Regarding S. scabiei, the overall seroprevalence was 11.6%, demonstrating the effectiveness and sensitivity of serology for large-scale application. Statistical analysis showed significant associations between infestation and both production category and farm biosecurity scores. These results highlight the importance of implementing biosecurity measures to limit mite spread at the farm level. 2. To evaluate and molecularly characterize several zoonotic protozoa and microsporidia of the gastrointestinal tract of pigs Several enteropathogens are shared between humans and pigs, including the protozoa Balantioides coli and Blastocystis sp., as well as the microsporidian species Enterocytozoon bieneusi. Accordingly, the second research line focused on investigating their prevalence and molecularly characterizing circulating variants, subtypes, and genotypes. Both copromicroscopic and molecular techniques were employed to this end. Specifically, aliquots of fecal samples collected from the 22 fattening farms recruited in the first research line were allocated for these laboratory analyses. A high prevalence of B. coli (92.4%) was observed using the sedimentation technique, which showed higher sensitivity compared to the FLOTAC® technique. Sequence analysis revealed the presence of both ITS genetic types (A and B), with type B being predominant. Regarding E. bieneusi, an overall prevalence of 63.4% was detected, with age and fecal soiling of the animal’s body significantly associated with infection. Molecular characterization identified several genotypes, all classified within Group 1, including two genotypes with documented zoonotic potential, both previously reported in humans. Blastocystis sp. was detected in all sampled animals, with both single and mixed infections involving subtypes ST1, ST2, ST3, ST5, and ST15. With the exception of ST15, all the aforementioned subtypes are considered zoonotic. Subtype ST5 was the most prevalent and its occurrence increased with age, suggesting a close association between the pig gut microbiota and the natural acquisition of ST5. Interestingly, it is rarely detected in humans. The data obtained offer valuable insights into the prevalence and molecular characterization of these pathogens in Italian pigs. Given that direct contact with pig feces is a major route of zoonotic transmission, clarifying the role of pigs as reservoirs is essential. Additionally, research is needed to explore their distribution across different pig production categories and in humans, including the potential association with clinical symptoms and individual susceptibility. Further studies are also required to assess their environmental persistence and survival in food and water matrices. 3. To investigate the role of wild boars as reservoirs of parasites for domestic pigs In collaboration with the Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia-Romagna, Cremona section, fecal samples from 191 wild boars hunted in northern Italy were collected and analyzed using different copromicroscopic and molecular techniques. In particular, the third research line aimed to identify major endoparasites in wild boars and determine their potential epidemiological link to domestic pig populations. A total of 172 out of 191 animals (90.1%) tested positive for at least one parasitic taxon and statistical analysis revealed a significant association between age and A. suum and B. coli prevalence. Furthermore, updated morphological and morphometric keys were provided for several coccidian species, as well as for third-stage larvae of the nematode Globocephalus urosubulatus, the latter further supported by molecular characterization. It is therefore crucial to ensure regular monitoring of wild boars as potential reservoirs of parasites for both livestock and humans, especially in urban and semi-urban settings.