SARS-CoV-2 (COVID-19): Fomites, Pets, & Transmission
Radford G. Davis, DVM, MPH, DACVPM, Iowa State University
Published April 8, 2020, at 9:00 PM CT. Updated April 21, 2020, at 4:56 PM CT.
Coronaviruses: A Primer
Coronaviruses are enveloped viruses that typically cause respiratory and enteric disease in humans and animals,1 notably camels, bats, masked palm civets, mice, swine, cattle, horses, chickens, turkeys, dogs, and cats.2-4 Five coronaviruses are known to circulate in humans: four that cause the common cold, and Middle East respiratory syndrome coronavirus (MERS-CoV), which appeared in Saudi Arabia in 2012.1 A sixth coronavirus, severe acute respiratory syndrome coronavirus (SARS-CoV-1), emerged in 2002 from China and has not been seen since 2003. A seventh severe acute respiratory syndrome coronavirus (SARS-CoV-2), which causes coronavirus disease (COVID-19), emerged in Wuhan, China, in late 2019 with some exposures linked to the Huanan Seafood Wholesale Market; it is currently circulating at pandemic levels.5 Evidence suggests that bats serve as the ultimate reservoir for at least two of the human common-cold associated coronaviruses as well as for MERS-CoV, SARS-CoV-1, and SARS-CoV-2, which infect humans through intermediate animal hosts.1,6-8
Transmission
SARS-CoV-2 is transmitted person-to-person via droplets generated from talking, coughing, and sneezing that fall off after approximately six feet and can also be transmitted via fomites (ie, contaminated surfaces and objects).9,10 There is some evidence that aerosol transmission may be possible.11-13
SARS-CoV-2 can survive on some surfaces to a limited extent.11,13 One experimental study examined the survival of SARS-CoV-2 on plastic, stainless steel, copper, and cardboard.11 No viable virus was detected on copper after 4 hours or on cardboard after 24 hours, but virus was viable up to 72 hours on plastic and stainless steel. SARS-CoV-2 genetic material was also detected on environmental surfaces in Huanan Seafood Wholesale Market in China.6,9,14 Studies of other human coronaviruses have demonstrated survival of up to 9 days on certain surface types, with length of persistence correlated to inoculum dose and ambient temperatures.15
Transmission from Pets
There is no evidence that domestic animals, or any animal within the United States, can serve as a source for human infection with SARS-CoV-2.16-19 Although dogs and cats have tested positive for SARS-CoV-2 on PCR and/or serology, there is no evidence that dogs develop clinical signs and limited evidence that cats do.20-25 There are concerns that companion animals could serve as fomites for transmission of SARS-CoV-2, particularly if the pet belongs to someone ill with COVID-19.
Although pet skin and fur are recognized sources for human infection for some parasites and microorganisms, there is no evidence that pets can serve as fomites for SARS-CoV-2.16,26-29 There is also no evidence that inanimate objects associated with pets such as collars, leashes, food or water dishes, can be fomites for SARS-CoV-2. Information and risk messaging regarding pet-to-human transmission may change as more information is collected.
Prevention Measures
To reduce the chances that a pet could become a fomite, the following is recommended17-19,30:
If a pet owner is ill with COVID-19, she/he should maintain separation from a pet, just as would be done for another member of the household. If possible, someone else may take care of the pet.
If a pet owner must care for a pet while ill, a face mask should be worn around the pet; hands should be washed before and after contact with the pet; hugging, kissing, and sleeping with the pet should be avoided (as well as being licked); and food, eating utensils, cups, bedding, or other items should not be shared. The pet should be kept indoors as much as possible.
For pet owners without symptoms, good hygiene should be practiced around the pet with hand washing before and after contact and feeding. Food and water dishes, toys, and bedding should also be washed regularly.
If a pet that has been in contact with someone with COVID-19 needs medical attention, the pet owner should call their veterinarian, who can discuss the urgency of the medical problem and help determine if the pet should be brought into the clinic for medical care.
All coronaviruses are enveloped and therefore readily killed by many biocidal agents, as well as washing with soap and water. Bathing the pet of someone who is ill may help reduce any chance the pet could be a fomite, but there is no scientific evidence at this time that supports this measure.