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Enterocytozoon bieneusi Was Detected for the First Time in Italian Wild Boar

Male wild boar in Genoa, Italy
Research: Disease, parasites & microbiology, Genetics & genomics

A 2026 parasite survey of wild boar (Sus scrofa) in central Italy detected Enterocytozoon bieneusi in eight of 46 animals, providing the first molecular evidence of this microsporidian in Italian wild boar. Microsporidians are microscopic parasites that can colonise intestinal tissue; some E. bieneusi genotypes are also known from humans and other animals. The animals were sampled during the 2023 hunting season in the Marche region, including hunting grounds in Ancona, Macerata and Fermo provinces and around Monti Sibillini National Park.

The study combined microscopy of faecal samples with molecular analyses of selected parasites of zoonotic interest. The broader aim was not limited to E. bieneusi: the researchers examined the gastrointestinal parasite community and then characterised Balantioides coli, Blastocystis and E. bieneusi in greater molecular detail.

Nearly half of the wild boar carried at least one parasite taxon

Microscopy detected at least one gastrointestinal parasite taxon in 22 of the 46 animals, or 47.8%. Nine positive animals carried one taxon, while 13 had coinfections with more than one. Thirteen parasite taxa were identified overall, including several groups of single-celled parasites and helminths, or parasitic worms.

Among the taxa examined further by molecular methods, Balantioides coli was confirmed in three of seven microscopy-positive animals. Blastocystis was characterised as subtype ST5 in two sequenced samples. These results placed the new E. bieneusi finding within a wider picture of gastrointestinal parasite diversity in wild boar from the study area.

Eight animals carried Enterocytozoon bieneusi DNA

Molecular testing detected E. bieneusi DNA in eight wild boar. Six sequences belonged to genotype D, while one each belonged to genotypes J and I. Phylogenetic analysis placed genotype D in Group 1, the group that includes genotypes with established zoonotic potential. Genotypes J and I clustered in Group 2.

The authors report that genotypes D, J and I had not previously been described from wild boar in any European country. They also note that genotype J had not previously been identified in either domestic pigs or wild boar worldwide. The Italian records therefore expand both the known geographic distribution of E. bieneusi in European wild boar and the known host range of genotype J.

The genotype pattern may connect wildlife and livestock epidemiology

The repeated detection of genotype D and the additional finding of genotype I are relevant because related genotypes have also been reported from domestic livestock. The authors discuss a possible epidemiological connection between wild boar and domestic swine populations in the study area, where semi-wild pig farming and cattle holdings can create opportunities for environmental overlap.

They present cross-species transmission or a shared environmental source as possible explanations, not as processes demonstrated by this survey. The study did not track transmission between individual hosts. Instead, the genotype pattern identifies a reason to examine the wildlife–livestock interface more closely.

The wider parasite community strengthens the One Health context

The study also detected parasites such as Giardia duodenalis, Ascaris spp., Trichuris sp. and gastrointestinal strongyles, alongside the molecularly characterised taxa. Some of these organisms or genotypes are relevant to animal or human health, although detection in wild boar does not by itself establish transmission to people or livestock.

The authors describe wild boar as having a dual epidemiological role: they can act as reservoirs for some parasites and as sentinels that reveal which potentially zoonotic organisms are circulating in shared environments. They therefore argue for integrated surveillance across wildlife, livestock and human health within a One Health framework, an approach that treats human, animal and environmental health as interconnected.

They also caution that the survey involved a limited number of animals and a restricted part of central Italy. The findings establish what was present in this sample and add new molecular records, but broader surveillance would be needed to determine how widespread the genotypes are across Italian wild boar populations.

Sources and image credit

  1. Cavallero, S., Rondón, S., Bellini, I., et al. (2026). Gastrointestinal parasites circulating in wild boars from central Italy and molecular characterization of Balantioides coli, Blastocystis sp. and Enterocytozoon bieneusi. Parasitology Research.Primary open-access CC BY 4.0 research article first published 2 July 2026. Forty-six wild boar from the Marche region were examined during the 2023 hunting season. Microscopy detected at least one gastrointestinal parasite taxon in 22 animals (47.8%), with coinfections in 13. Molecular analyses detected Enterocytozoon bieneusi in eight animals: six genotype D and one each genotypes J and I; genotype D clustered in zoonotic Group 1.

Image: Cellofilo — male wild boar in the Bisagno river area of Genoa, Italy, 3 June 2017; Wikimedia Commons; CC BY 4.0. Representative image, not one of the wild boar sampled in the Marche study. · CC BY 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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