COVID-19 (also known as Coronavirus Disease 2019) is a disease due to infection by a subtype of coronavirus. When infected, humans may show few, if any, symptoms and often mistake it for the common cold. Symptoms of COVID-19 include fever, coughing, and difficulty breathing.
Coronaviruses were identified in the mid-1960s and are known to infect humans and a variety of animals (including birds and mammals). These are enveloped RNA viruses in the order of Nidovirales. When viewed under an electron microscope, the virus has a crown-like appearance which is why it was named after the Latin word corona, meaning ‘crown’ or ‘halo’.
There are four main types of coronavirus: Alphacoronavirus, Betacoronavirus, Deltacoronavirus, and Gammacoronavirus.
The most significant characteristic of coronaviruses is their ability to mutate which ultimately means they have the potential to jump hosts relatively easily.
To date, there are seven coronaviruses that are known to infect humans and cause disease:
- The common cold: can be due to infection by Betacoronavirus HCoV-OC43, Betacoronavirus HCoV-HKU1, or Alphacoronavirus HCoV-229E. (Please note that there are over 200 viruses that have been linked to symptoms of the common cold including Rhinovirus, the most common virus associated with human colds)
- Pseudo-croup and bronchiolitis in children: due to Alphacoronavirus HCoV-NL63
- Severe Acute Respiratory Syndrome (SARS): due to Betacoronavirus SARS-CoV
- Middle East Respiratory Syndrome (MERS): due to Betacoronavirus MERS-CoV
- COVID-19: believed to be due to a novel Betacoronavirus which is genetically very similar to the one that caused SARS. This virus is still being studied.
For SARS-CoV, bats were the likely origin of the virus, which further spread to Himalayan palm civets, Chinese ferret badgers and raccoon dogs at the wet markets of Guangdong, China. People handling or consuming these animals were infected and further spread the virus through human-to-human transmission.
For MERS-CoV, dromedary camels are important animal reservoirs of the virus and are considered the main intermediate animal host source for human MERS-CoV infections. Contact with infected animals can be a route of infection. Zoonotic infections due to the consumption of raw camel milk, or other camel products related to MERS-CoV infections have also been reported. Once in the human population, the virus spreads person-to-person and has resulted in healthcare-associated outbreaks, particularly in Saudi Arabia, the United Arab Emirates, and South Korea. This leads to the transmission of the virus to people sharing a room with a MERS patient or to healthcare workers and visiting family members tending to MERS infected individuals.
For COVID-19, the exact origins of this strain of the coronavirus is still under investigation. Initial reports suggested that the virus may have been introduced from snakes but this has been disproven. Current studies are focusing on bats and pangolins as potential sources of this coronavirus.
The transmission of COVID-19 from person-to-person is primarily through respiratory droplets produced when an infected person coughs or sneezes. It may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this is not thought to be the main way the virus spreads.
According to the U.S. Centers for Disease Control and Prevention, a few pets — including cats and dogs — also have been infected with the virus that causes COVID-19. This happened mostly after the animals were in close contact with people infected with the COVID-19 virus.
Based on the limited available information, the risk of animals spreading the COVID-19 virus to people is considered low. Animals don't appear to play a significant role in spreading the virus that causes COVID-19.
While mammals are mostly infected by alphacoronaviruses or betacoronaviruses, birds are predominantly infected by deltacoronaviruses and gammacoronaviruses. Within the gammacoronavirus group, the main representative is avian coronavirus which is known to cause Infectious Bronchitis, a highly contagious disease in chickens. There have been no reports of transmission of avian coronaviruses to people.
Ferrets are commonly infected by coronaviruses but none of these are transmissible to people. The two most common coronarvirus infections in ferrets are both alphacoronaviruses: Ferret enteric coronavirus (FRECV) and ferret systemic coronavirus (FRSCV). FRECV is associated with foul smelling diarrhea, dehydration, anorexia, hyporexia, lethargy, weight loss, and vomiting. FRSCV is an emerging fatal disease seen in young ferrets (average age 11 months) and is progressive throughout several weeks to months. Clinical signs include anorexia, weight loss, diarrhea, and large intra-abdominal masses.
In 1961, an infectious disease in rabbits was identified which resulted in significant damage to the heart. This was later recognized as an Alphacoronavirus but further differentiating of the virus has not been completed. This virus is so reliable at causing heart disease in rabbits that it has been used in laboratory settings as the animal model for studying heart disease development in humans. Young rabbits aged 3 to 10 weeks have been shown to be susceptible to rabbit enteric coronavirus. This disease leads to profuse watery diarrhea, poor growth, and acute death. Again, neither of these rabbit viruses have been found to be a source of disease for people.
- A small number of pets worldwide, including cats and dogs, have been reportedexternal icon to be infected with the virus that causes COVID-19, mostly after close contact with people with COVID-19.
- Based on the limited information available to date, the risk of animals spreading COVID-19 to people is considered to be low.
- It appears that the virus that causes COVID-19 can spread from people to animals in some situations.
- Treat pets as you would other human family members – do not let pets interact with people outside the household.
- If a person inside the household becomes sick, isolate that person from everyone else, including pets.