Tritrichomonas is a microscopic parasite which lives in the large intestines of cats, where it causes diarrhoea. Without intervention, affected cats may have diarrhoea for several years before clearing the infection naturally! Although cats of all ages can develop tritrichomonas diarrhoea, it is most commonly seen in young cats and kittens, and these cats often have a history of being in multi-cat environments such as rescue shelters.
Tritrichomonas is spread through faeces, which is why the risk of infection is higher in places where there are multiple cats. The parasite can also survive for a short time in wet faeces, cat food and water, and this means that transmission can occur between cats who are not in direct contact.
Young pedigree cats, especially Siamese and Bengals, have been shown to be more likely to be infected in the UK. Tritrichomonas is a parasite of cats and cattle, and does not affect humans.