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Astrovirus Outbreak in an Animal Shelter Associated with Feline Vomiting

Li Y, Gordon E, Idle A, et al. Astrovirus Outbreak in an Animal Shelter Associated with Feline Vomiting. Front Vet Sci. 2021;8. doi:10.3389/fvets.2021.628082

Vomiting and diarrhea are common presentations in domestic cats, and may occur frequently as outbreaks in shelter cats. These outbreaks are often caused by well described organisms, such as a panleukopenia virus, giardia, or others. Dietary changes and stress are also common causes of GI distress. Astroviruses are non-enveloped, single-stranded, positive-sense RNA viruses that resemble a star in shape. They are common causes of diarrhea in human infants and have been associated with disease in a wide range of veterinary species.

The purpose of this paper was to describe an outbreak of vomiting and diarrhea in a population of shelter cats that is suspected to be due to an outbreak of an astrovirus.

From December 2019 to Jan 2020 an outbreak of vomiting occurred in an animal shelter in British Colombia, Canada. Twelve cats were identified with acute onset vomiting without any identified cause. Most cats did not have any evidence of concurrent diarrhea (only one cat). Aside from two co-housed pairs, cats did not have direct contact with each other. Clinicals signs were often prolonged (median 9.8 days, range 1-31), but decreased dramatically in incidence when control measures (disinfection, cessation of cat movement, isolation protocols) were instituted. No fatalities were noted.

Fecal samples were available from 10 of these 12 cats and vomit from 7 of the 12, for a total of 11 of the 12 cats with samples collected. 19 unaffected cats were also present in the shelter at this time who had fecal samples collected to act as controls. Longitudinal samples were collected when possible, with the number of samples per cat ranging from 1 to 18.

Fecal samples were subjected to a commercial real-time PCR panel (IDEXX Diarrhea Panel) to look for possible pathogens. Of the clinically affected cats, three were weakly positive for clostridium perfringens alpha toxin gene (commonly encountered in subclinical animals), two were weekly positive for panleukopenia virus (suspected to be vaccine induced), and one was positive for feline coronavirus. No explanation for the vomiting was identified. As such, metagenomic analysis was performed on fecal samples from control and case cats. Nucleic acids were isolated and amplified, and several viruses were identified based on in silico analysis from pooled samples in the groups of cats. Four of the virtues were considered less relevant, and so the astrovirus genome was sequenced and found to match that of common mammalian astroviruses. Rt-PCR was performed on all of the fecal samples and astrovirus was isolated from 10 of the 11 samples. Five of the nine control cats tested were also positive for astrovirus.

In order to determine if astrovirus infection is endemic in the healthy cat population, fecal samples from 18 cats collected a year before and a year after the outbreak were tested for astrovirus by PCR and were all negative.

Based on this data, the authors conclude that infection with an astrovirus was likely the cause of vomiting in this group of cats, and that astrovirus infection may represent a contagious cause of vomiting in cats.

A limitation to this study was its observational nature. While the correlation between astrovirus infection and vomiting was documented, the possibility that it is a secondary pathogen, opportunist, or other non-causative agent remains a possibility. There were also a very small number of cats affected, making large scale associations difficult. The detection of astrovirus in control cats may indicate that infection does not cause disease in all animals, or may imply that it was not responsible for vomiting.

Overall, this study suggests that an astrovirus may be a cause of contagious vomiting in domestic cats. Further work is needed to clarify its role in disease.

See Also
1. Donato C, Vijaykrishna D. The broad host range and genetic diversity of mammalian and avian astroviruses. Viruses. (2017) 9:102. doi: 10.3390/v9050102
2. Boujon CL, Koch MC, Seuberlich T. The expanding field of mammalian astroviruses: opportunities and challenges in clinical virology. Adv Virus Res. (2017) 99:109–37. doi: 10.1016/bs.aivir.2017.07.002
3. Cortez V, Meliopoulos VA, Karlsson EA, Hargest V, Johnson C, Schultz-Cherry S. Astrovirus biology and pathogenesis. Annu Rev Virol. (2017) 4:327–48. doi: 10.1146/annurev-virology-101416-041742

Related Blog Posts
1. Survival and outcomes in shelter cats with feline panleukopenia virus infection: https://everycat.org/cat-health/survival-and-outcomes-in-shelter-cats-with-feline-panleukopenia-virus-infection/
2. Survival of orphan shelter kittens under treatment for diarrhea: https://everycat.org/cat-health/survival-of-orphan-shelter-kittens-under-treatment-for-diarrhea/
3. Disease Control in Animal Shelters: https://everycat.org/cat-health/disease-control-in-animal-shelters/