In the Literature
Sila T, Sunghan J, Laochareonsuk W, et al. Suspected cat-to-human transmission of SARS-CoV-2, Thailand, July-September 2021. Emerg Infect Dis. 2022;28(7):1485-1488. doi:10.3201/eid2807.212605
The Research …
Early in the coronavirus disease (COVID-19) pandemic, there were concerns for potential severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection of domestic animals and the possible human and animal health implications. SARS-CoV-2 was found to infect a range of animals, including dogs and cats, but public health implications remained unclear.1-5 Identification of zoonotic transmission is challenging when there is high risk for human-to-human exposure, and it was therefore assumed that unique circumstances would be required to identify zoonotic transmission of SARS-CoV-2.
This article describes events that allowed for a strong presumptive diagnosis of cat-to-human transmission of SARS-CoV-2. A cat’s owners developed COVID-19 and required hospitalization; however, there was a lack of available beds, so they were transferred to a hospital 559 miles (900 km) away. The cat was also transported in the ambulance and was sent to a university veterinary hospital on arrival.
Although the cat was clinically normal, nasal and rectal swabs to test for SARS-CoV-2 were collected because of the cat’s close contact with infected owners. During sample collection, the cat sneezed in the face of a clinician who was wearing an N95 mask but no eye protection. Three days later, the clinician developed COVID-19 and was hospitalized.
Viral genomics revealed that the cat’s owners, cat, and clinician were infected with the same strain of SARS-CoV-2, which was different from strains circulating in the province where the clinician lived. In addition, the clinician had no known contact with humans from the owners’ province. This evidence supported transmission of the virus from the owners to the cat, with subsequent infection of the clinician.
The broader relevance of this finding is unclear. Transmission of SARS-CoV-2 between humans and companion animals may be rare or common but not recognized because of lack of testing, lack of consideration of pets as a source of infection, and difficulty confirming zoonotic exposure with widespread human-to-human transmission. Although zoonotic infections are likely rare, they can occur.
... The Takeaways
Key pearls to put into practice:
Veterinary staff are more likely to be exposed to SARS-CoV-2 from infected humans, but there is some risk from typical clinical handling of infected cats. The risk from dogs is unclear and likely lower but cannot be ruled out.
Eye protection is underused in veterinary medicine. Ocular mucous membranes are a potential route of entry for many pathogens, including zoonotic respiratory viruses. If a mask is indicated, concurrent eye protection (ie, goggles, face shield) is often beneficial.
The magnitude of risk from SARS-CoV-2–exposed dogs and cats is unclear and may be low, but cat-to-human transmission can occur, even with a clinically normal patient. Use of respiratory and eye protection when handling exposed cats (and potentially dogs) is an easy and reasonable precaution.
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