Scientists have found a new canine coronavirus in a few individuals hospitalized with pneumonia. This may seem alarming, but once we unpack it, you will understand that there’s no reason to lose any sleep.
The discovery of the canine coronavirus in eight people in a hospital in Sarawak, Malaysia, was reported in Clinical Infectious Diseases by a group of highly regarded international scientists. So does this mean dogs can spread coronaviruses to humans ?
The first point to clarify is exactly what canine coronavirus is. Importantly, it’s quite different from SARS-CoV-2, the virus that causes COVID-19. The coronavirus family can be divided into four groups of viruses: alpha, beta, gamma and delta coronaviruses. SARS-CoV-2 falls within the group, whereas the canine coronaviruses are in the entirely distinct alphacoronavirus group.
Researchers have known about canine coronaviruses for almost 50 years. These viruses have been around in relative obscurity over the majority of this time, being of interest only to veterinary virologists and occasional puppy owners. There are no prior reports of those viruses infecting people. But the sudden global spotlight on all coronaviruses is finding coronaviruses in areas we haven’t looked before.
The canine coronavirus infections recently identified in people were actually discovered serendipitously. Scientists were not specifically looking for canine coronavirus, and the patients involved had long since recovered. The researchers were trying to create a new test that could detect all sorts of coronaviruses at precisely the identical time – a so-called pan-CoV test .
After confirming the evaluation worked on samples of viruses grown in labs, they tested it on 192 human swabs from hospitalized pneumonia patients in Malaysia. Nine of these samples tested positive for coronavirus.
Further analysis showed that five out of the nine samples were ordinary human coronaviruses which can cause colds. But surprisingly, four of the samples were canine coronavirus. Further study of patients in the same hospital revealed four more positive patients.
The researchers studied nose and throat swabs from all eight Malaysian patients to try to learn more about the canine coronaviruses. Samples were put onto dog cells in the laboratory to see whether any live virus was present. Virus from a single sample replicated well, and virus particles could be viewed using electron microscopy. The scientists were also able to order the virus’s genome.
The analysis found that this canine coronavirus was closely associated with a couple different alphacoronaviruses – including those from pigs and cats – and showed it had not previously been identified anywhere else.
No evidence of onward spread
Was canine coronavirus responsible for the pneumonia in the patients? Right now, we simply can’t tell. Seven out of eight patients were concurrently infected with another virus, either adenovirus flu or parainfluenza virus. We know that each one of these viruses can cause pneumonia by themselves, so it is more probable that these were responsible for the illness. We can say there is an association between pneumonia and canine coronavirus in these patients, but we could ’t say it’s the cause.
There have been concerns that the canine coronavirus identified in these Malaysian patients could spread from person to person, causing a wider outbreak. What many headlines don’t explain is that these human infections really occurred in 2017 and 2018. This makes the likelihood of a canine coronavirus outbreak from this source even lower as there’s not any evidence of onward spread in the intervening three to four years.
As coronaviruses have become the center of attention and we search for related viruses, we’re inevitably going to find more positive samples in unexpected places. The huge majority of these can be of academic interest only and need not raise alarm. However, it’s crucial that surveillance for new coronaviruses continues and expands so that we have the best possible chance of identifying significant cross-species jumps later on.