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Zoonoses are infections whose etiologic agents are transmitted from animal reservoirs to human hosts, either directly or via insect vectors. The number and variety of zoonoses are increasing due to the burgeoning geographic spread of insect vectors and contact with feral animals as human populations expand into and alter previous wilderness areas. The origin of the current COVID-19 pandemic is likely due to the zoonotic transmission of the coronavirus SARS-CoV-2 from its usual animal host, the bat, to humans.
Now, the Centers for Disease Control and Prevention report the first cases of apparent reverse-zoonotic transmission of SARS-CoV-2 from humans to domestic cats. During the peak of human COVID-19 cases in New York state, two cats — one living with five humans in an apartment in Nassau County, the other in a house with one human occupant in Orange County — developed respiratory illnesses 1 week apart that were characterized by sneezing, ocular discharge, and lethargy. Both cats recovered fully in about 8 days from illness onset.
Testing by the same laboratory of nasal, oropharyngeal, and ocular discharge using SARS-CoV-2 reverse transcription polymerase chain reaction was positive for both cats. One of the cats also tested positive for Mycoplasma felis. In both cases, a history of COVID-19-like illness was reported in the humans living with the cats about a week before each cat became ill. There was no interaction between the two households and no evidence of further transmission from cats to humans or vice versa.
Newman A et al. First reported cases of SARS-CoV-2 infection in companion animals — New York, March–April 2020. MMWR Morb Mortal Wkly Rep 2020 Jun 12; 69:710. (https://www.cdc.gov/mmwr/volumes/69/wr/mm6923e3.htm)
Comment
Millennia of cohabitation between humans, dogs, and cats seem to have produced relationships among which relatively few infectious agents are routinely transmitted. It now seems clear that SARS-CoV-2 virus can be spread from humans to cats. Acute respiratory illness in domestic animals should be reported to local health authorities who, with the aid of the newly formed U.S. One Health Federal Interagency COVID-19 Coordination Group, will ensure that the epidemiology of these cases is thoroughly investigated. Although there is no information suggesting that coronavirus transmission can move from pet to human, the asymptomatic presentation of this disease in many cases makes it vital that we investigate this potential pathway to the fullest extent possible.