Cat genotype Tritrichomonas foetus survives passage through the alimentary tract of two common slug species

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Abstract

Tritrichomonas foetus has recently been recognised as the cause of large bowel diarrhoea in cats (feline trichomoniasis), for which the epidemiology is largely unknown. We tested whether garden slugs common in Sydney, Australia can pass viable T. foetus in their faeces after oral intake. First, Leopard slugs (Limax maximus) were offered cat food with 104 of T. foetus per gram, 63% (5/8) of slugs consumed food with T. foetus and subsequently 20% (1/5) shed T. foetus in their faeces. Furthermore, 63% (5/8) and 75% (6/8) of the Leopard slugs and the Yellow cellar slugs (Limacus flavus) consumed food with 106 of T. foetus per gram and subsequently 100% (5/5) and 83% (5/6) shed T. foetus in their faeces, respectively. These results suggest that slugs may facilitate passive transmission of T. foetus between cats. We speculate that cats may become infected with T. foetus should they consume food contaminated with faeces from slug(s) infected with T. foetus.

Introduction

Tritrichomonas foetus is a protozoan parasite that has attracted recent attention in feline medicine, where it has been identified as the cause of chronic large bowel diarrhoea in cats – feline trichomoniasis (Gookin et al., 2001, Gookin et al., 2004, Levy et al., 2001, Levy et al., 2003, Bell et al., 2010). In the past, T. foetus was best known as the causative agent of bovine trichomoniasis, a venereal disease of naturally bred cattle associated with abortions and infertility (Felleisen, 1999, Rae and Crews, 2006). Comparative studies have been undertaken to explore the link between feline and bovine trichomoniasis and have revealed important biological and genetic differences between bovine and feline isolates of T. foetus (Stockdale et al., 2007, Stockdale et al., 2008, Šlapeta et al., 2010). The consistent genetic differences between T. foetus isolated from cats and cattle supports recognition of the cat and cattle genotypes of T. foetus (Šlapeta et al., 2010). Accordingly, epidemiological and biological characterisation of the cat genotype T. foetus is of great interest to feline clinicians and basic scientists alike.

Transmission of T. foetus between cats is thought to involve faecal-oral transmission. Therefore, multi-cat environments, use of common litter trays and close proximity between cats are considered major risk factors for spread of T. foetus infections (Gookin et al., 2001, Gookin et al., 2004, Bissett et al., 2008). To better understand the transmission of T. foetus between cats, we have focused on the ability of the cat genotype of T. foetus to survive outside the host and have demonstrated that viable T. foetus can survive in cat faeces for several hours, or even days (Hale et al., 2009). This degree of environmental resilience has prompted us to investigate, whether ubiquitous molluscs (i.e. slugs known to eat cat faeces) may facilitate passive transmission of T. foetus in areas occupied by cats.

The aim of this study was to investigate whether slugs are capable of excreting viable T. foetus after ingesting viable trophozoites. Two common species of garden mollusc, the Leopard slug (Limax maximus) and the Yellow cellar slug (Limacus flavus), were fed trophozoites of T. foetus cat genotype. The presence of organisms in their faeces was subsequently monitored for 14 days post initial feeding on viable trophozoites (p.i.). This report provides the first direct evidence that T. foetus can survive passage through the alimentary tract of slugs.

Section snippets

The parasite T. foetus cat genotype

A cat genotype T. foetus (Riedmüller, 1928), designated G10/1 was obtained from a 12-week-old castrated Tonkinese kitten with ongoing diarrhoea containing blood and mucus (Šlapeta et al., 2010). The axenised culture was genotyped, as described (Šlapeta et al., 2010). The culture was maintained as described in Section 2.2, and cryopreserved in liquid nitrogen using 10% dimethyl sulfoxide.

The culture media

Modified Diamonds Medium (MDM) was prepared using trypticase (BD 211921), yeast extract, maltose, 10% sheep

Gut transit time of slugs is typically 24 h

After feeding small slices of carrot to a group of Leopard slugs, carrot-coloured faeces could be detected in 40% (4/10) of slugs within 12 h. After 24 h in 80% (8/10) of the slugs had defecated carrot-coloured faeces. The remaining two slugs refrained from eating during the experimental period.

T. limacis in Australian slugs

A number of parasites were detected in the faecal samples of slugs prior to experimental feeding on T. foetus. The trichomonad, T. limacis could be detected in the faeces of 15% (3/20) L. maximus and 20%

Discussion

In this investigation, we have demonstrated that two common species of slugs from the Sydney metropolitan area can be fed, and subsequently excrete viable T. foetus in their faeces for 24–48 h post initial feeding. This provides direct experimental evidence that T. foetus is a resilient parasite within the environment, and that slugs may facilitate passive transmission of the parasite between cats.

Slugs are a very diverse group of molluscs commonly labelled as pests, where they have been known

Acknowledgements

We thank Richard Malik, Jan Tachezy, David Emery and Simon Craig for insight and Michael Shea for help with slug identification, and Denise Wigney and Jan Van Ekris for help with slug collection. The study was in part supported by the Faculty of Veterinary Science, University of Sydney through an internal support for the Honours project of the first author.

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