Epidemiology of Aujeszky disease in wild boars (Sus scrofa L.) in Croatia

Aujeszky disease (AD) or pseudorabies is a viral disease of domestic and wild animals caused by the Suid alphaherpesvirus 1. In wild boar infection usually undergo latent phase but under certain conditions reactivation of the virus can result in a disease. Seroprevalence in wild boars ranges from 0.8 to 100%, and is among other influenced by region, type of management, age and sex of the studied animals. In this study we analyzed blood, lungs, olfactory bulbs and spleen from 222 free-living wild boars from different localities in Croatia and compared results obtained by ELISA with PCR, sex, age and locality. Total seroprevalence was 33.78%, ranging from 25.26% in males to 40.15% in females (p = 0.0346; χ2 = 4.47). According to the age categories prevalence was 10% in offspring, 27.53% in subadults, and 66.75% in adults. Seroprevalence in adult males (66.66%) and females (65.30%) was almost identical. In males, significantly lower seroprevalence was detected in offspring compared to subadults (χ2 = 4.07, p < 0.05) and adults (χ2 = 31.04; p < 0.05), and in subadults compared to adults (χ2 = 15.13; p < 0.0001). Among females, adults had a significantly higher prevalence compared to offspring (χ2 = 19.27; p < 0.0001) and subadults (χ2 = 8.62; p < 0.01). Analysis between counties revealed Sisačko-moslavačka county as a hot-spot for AD. None of the samples was positive for ADV antigens. The observed trend in prevalence points to the fact that the main transmission occurs during one part of the year (most probably the mating season). Also, triggers for virus reactivation might be more complex than previously thought, since none of our samples, collected during the mating and hunting season, was PCR positive. Finally, we can conclude that adult males represent the main transmission link between different wild boar groups.

The First Description of Setaria Tundra (Issaitshikoff & Rajewskaya, 1928) in Roe Deer from Croatia

Genus Setaria, Viborg 1795, comprises 46 species that parasitize in the peritoneal cavity of Artiodactyla, Perissodactyla and Hyracoidea. The majority of these infections pass unnoticed, but occasionally they can induce severe peritonitis or neurological signs in aberrant hosts and, rarely, even in humans. In this paper we describe for the first time the finding of Setaria tundra in roe deer in Croatia. We examined 45 roe deer and determined the presence of Setaria nematodes in 24.4% of samples, which were subsequently diagnosed as Setaria tundra using molecular methods.

Evolution of MHC class II SLA-DRB1 locus in the Croatian wild boar (Sus scrofa) implies duplication and weak signals of positive selection

The wild boar is an ancestor of the domestic pig and an important game species with the widest geographical range of all ungulates. Although a large amount of data are available on major histocompatibility complex (MHC) variability in domestic pigs, only a few studies have been performed on wild boars. Due to their crucial role in appropriate immune responses and extreme polymorphism, MHC genes represent some of the best candidates for studying the processes of adaptive evolution. Here, we present the results on the variability and evolution of the entire MHC class II SLA-DRB1 locus exon 2 in 133 wild boars from Croatia. Using direct sequencing and cloning methods, we identified 20 SLA-DRB1 alleles, including eight new variants, with notable divergence. In some individuals, we documented functional locus duplication, and SLA-DRB1*04:10 was identified as the allele involved in the duplication. The expression of a duplicated locus was confirmed by cloning and sequencing cDNA-derived amplicons. Based on individual genotypes, we were able to assume that alleles SLA-DRB1*04:10 and SLA-DRB1*06:07 are linked as an allelic combination that co-evolves as a two-locus haplotype. Our investigation of evolutionary processes at the SLA-DRB1 locus confirmed the role of intralocus recombination in generating allelic variability, whereas tests of positive selection based on the dN/dS (non-synonymous/synonymous substitution rate ratio) test revealed atypically weak and ambiguous signals.

New data on wild boar (Sus scrofa L.) a dead-end host for large American liver fluke (Fascioloides magna)

Fascioloidosis is a parasitic disease of primary wild and domestic ruminants, caused by a digenean trematode, Fascioloides magna. The final hosts of F. magna are divided according to the host-parasite interactions into definitive, dead end and aberrant. The clinical appearance, pathology, outcome of disease, and its importance in disease epidemiology vary with different host types. According to this division, wild boar (Sus scrofa) are characterized as a dead end host. In this paper we analysed 12 wild boar livers from Croatia. Eleven of them contained pigment traces, pseudocysts, degrading pseudocysts, fluke migratory channels, live and degrading flukes. F. magna eggs were found in pseudocysts, but no eggs were recovered from faeces. Concurrent infection with F. magna and Fasciola hepatica was detected in one liver. According to everything we observed, wild boar currently has no direct role in maintaining and spreading the disease.