High prevalence of Tritrichomonas foetus 'bovine genotype' in faecal samples from domestic pigs at a farm where bovine trichomonosis has not been reported for over 30 years

- We report 65% prevalence of Tritrichomonas foetus in pigs from a mixed farming system with T. foetus negative cattle.
- T. foetus identity was confirmed by culture, real-time PCR and conventional PCR.
- We found the 'bovine genotype' T. foetus in pigs based on multi-locus genotyping.
- Negligible risk of transmission of T. foetus from pigs to cattle.

Bovine venereal trichomonosis caused by the flagellate Tritrichomonas foetus is a notifiable disease in Australia. While, T. foetus is pathogenic in both cattle and cats, it has long been established that the same T. foetus colonises the stomach, caecum and nasal cavity of pigs without apparent clinical significance. Multi-locus genotyping grouped the non-pathogenic porcine T. foetus with the pathogenic 'bovine genotype', rather than with the 'feline genotype' T. foetus. Bovine trichomonosis is now uncommon due to wide-spread use of artificial insemination, however, whether T. foetus remains prevalent in pigs where bovine trichomonosis has been eradicated remains unknown. We surveyed faecal samples from pigs farmed in close proximity with T. foetus-negative cattle. The Modified Diamond's Medium assay used were 77.4% (24/31) positive for trichomonads and 64.50% (20/31) were T. foetus-positive based on real-time PCR and conventional PCR. An axenic reference strain of T. foetus, designated PIG30/1 was established. In addition, a novel trichomonad ITS rDNA, PIG12, closely related to sequences from Trichomitus spp is reported. Multi-locus genotyping at nine loci matched PIG30/1 to the 'bovine genotype' T. foetus. In conclusion, cross-species transmission of T. foetus between pigs and cows from environmental exposure of T. foetus-contaminated pig faeces is unlikely. Domestic T. foetus-positive pigs possess a negligible risk of a successful T. foetus transmission event to cattle.

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