Helminths of Wild Boar (Sus scrofa) in the Calabrian Region of Southern Italy Open Access

The population of wild boar (Sus scrofa Linnaeus, 1758) has sharply increased in population throughout Europe in the past few decades (Spagnesi and De Marinis 2002). In Italy, the wild boar occurs in a great variety of habitats, from the intensely anthropized areas of the foothills to true mountainous zones (Carnevali et al. 2009). Among Italian ungulates, it plays a very particular role, both for some intrinsic biologic characteristics (i.e., potential population growth rates) and because it is undoubtedly the most manipulated game species. In Calabria, as in other Italian regions, the wild boar (S. scrofa) population has experienced a considerable increase in the last few years (Monaco et al. 2010). The autochthonous Sus scrofa majori has been replaced by Sus scrofa raiseri, imported into the area, and in some cases, by hybrids with feral domesticated pig (Sus scrofa domesticus). Both subspecies are characterized by larger body sizes, greater dimensions, higher reproductive rates, and a considerable phenotypic variability. Moreover, they have a greater adaptability toward less favorable habitats devoid of natural predators. These factors have caused a rapid expansion of the subspecies S. scrofa raiseri in southern Italy (Pedrotti et al. 2001; Carnevali et al. 2009; Provincial Administration of Catanzaro, Agriculture Sector 2011). Widespread throughout the national public lands, S. scrofa raiseri currently has serious management problems (Apollonio et al. 1988). In the region of Calabria, the presence of this wild game ungulate was detected in all provinces (Pedrotti et al. 2001; Carnevali et al. 2009; Provincial Administration of Catanzaro, Agriculture Sector 2011). Due to the excessive population of wild boar in the province of Catanzaro, selective hunting for the control of this species was introduced (Provincial Administration of Catanzaro, Agriculture Department 2012). This wild ungulate is the final host for many endoparasites (De La Muela et al. 2001; Rajković-Janje et al. 2002; Foata et al. 2005; Navarro-Gonzalez et al. 2013). Helminths are mainly detectable by microscopic examination of feces. Some of them have high specificity for pigs but can be transmitted to other livestock species (Foreyt 2001; Genchi et al. 2010; Taylor et al. 2010). There is a lack of data regarding helminths in the gastrointestinal (GI) and hepatic systems of wild boar populations in the province of Catanzaro. We focused our work on this area of study by using microscopic fecal examination.

We gathered data from September 2014 to December 2014 on wild boars culled during the 2014–15 hunting season. The animals were from a hunting territory about 215 km² situated in the areas of Sila and Presila (a mountainous area of Calabria; 39°22′N, 16°30′E). The animals came from 60 capture points distributed in four municipalities of Cicala, Taverna, Sorbo San Basile, and Carlopoli, at an average elevation of 994 m; all municipalities were within the province of Catanzaro with respect to game management (Fig. 1).

In each of these municipalities, 15 specimens were subjects of a parasitologic examination. The search for parasites used fecal material collected in the field from the dissected terminal colon and rectum, with a minimum of 10 g/subject. All data concerning the animal (sex, weight, estimated age, hybridization signs, place and date of culling, and GPS coordinates) were also collected. All samples and reports were transported together in disposable hermetic containers, at 4 C, to the Interdepartmental Center of Veterinary Service located within the Human and Animal Health Unit of Parasitic Disease at the University of Catanzaro “Magna Graecia,” Catanzaro, Italy. We collected a total of 60 fecal samples from 34 males and 26 females of different estimated ages (mean age of 4 yr). We estimated animal ages following the ministerial guidelines (Monaco et al. 2010).

Fecal microscopic exams were performed by using the FLOTAC dual technique, which is based upon the use of two flotation solutions that are used in parallel on the same fecal sample. A sodium chloride–based solution with a specific gravity of 1.200 was used to detect nematode and cestode eggs, and a zinc sulfate–based solution (specific gravity=1.200) was used to detect lungworm larvae and trematode eggs (Fasciola hepatica and Dicrocoelium dendriticum) and for nematodes, such as Ascaris suum and Trichuris suis. The analytic sensitivity of the FLOTAC dual technique was 2 eggs/g (EPG) of feces (Cringoli et al. 2010; Rinaldi et al. 2010).

For statistical analysis, data from each sample were divided into three categories: juvenile categories that consisted of 15 animals (nine males and six females) up to 18 mo of age (mean=18.1 mo, SD=2.3); adult categories that consisted of 25 animals (eight males and 17 females) between 18 mo and 4 yr of age (mean=3.4 yr, SD=1.7); elderly categories that consisted of 20 animals (17 males and three females) over the age of 4 yr (mean=6.1 yr, SD=1.2). All data were analyzed by analysis of variance and Pearson correlation tests. Statistical significance was considered as P<0.05 and P<0.01 with the software IBM SPSS® Statistics (version 20.0, IBM Corporation, Armonk, New York, USA).

The most common parasitic elements that we found were the eggs of GI helminths, such as the roundworms (A. suum), present in 88% (53/60) of the examined animals, followed by GI strongyles 82% (49/60), T. suis 37% (22/60), and finally by Strongyloides ransomi 15% (9/60). The lungworms, Metastrongylus spp., were present in 60% (36/60) of wild boars examined, while hepatic helminths, D. dendriticum were present only in 2% (2/60) of the examined animals. The mean parasitic intensities were A. suum (252 EPG), GI strongyles (111 EPG), T. suis (8 EPG), Strongyloides ransomi (8 EPG), Metastrongylus spp. (13 EPG), and D. dendriticum (1 EPG).

The full survey results are categorized and summarized in Table 1, where we report (for each species or class) the number of animals with positive results, the respective parasitic prevalence (percentage) with 95% confidence interval, mean parasite intensity, and parasite load, with the range expressed in EPG. We found no significant correlations among parasitic prevalences with the sex and age of the examined animals (Table 2).

Our research described the presence of several helminths in the wild boar in natural conditions of the Sila and Presila areas of Catanzaro. The lack of previous studies on parasites of the wild boar in the Calabria region prevent the comparison of our data with historic data. It is, nevertheless, possible to make a comparison with studies conducted in other regions of Italy. Our results, with the exception of A. suum, accord with other surveys conducted on national territory (Macchioni et al. 1988; Poglayen et al. 1991; Candotti et al. 1996; Magi et al. 2005; Moretta et al. 2011). The higher prevalences of A. suum and T. suis, compared with the other groups of helminths, could be attributed the continued practice of crossing domestic pigs (S. scrofa) with wild boar in the areas of Sila and Presila of Catanzaro. These animals are often released in the territory. In our opinion, the contact of wild boar with domestic pig (S. scrofa domesticus) has favored helminthiasis in the study area and has yielded high parasite populations. This hypothesis is also supported by the presence of six animals (10%), with evident signs of hybridization. The parasitologic scenario suggested that wild boars are the final host of the most common endoparasites of the domestic pig and represent an important reservoir for it. This scenario could have health consequences due to the poor biosecurity of typical family farms in the area. Because they serve as reservoirs for parasites, we recommend increased scientific research on wild boars in Calabria, combining both sanitary monitoring and population reductions to preserve both the wild species and domestic breeds.