Scientists have found one new canine coronavirus in a handful of people hospitalized with pneumonia. It may sound alarming, but once we unpack it, you will see that there is no reason to lose sleep.
The discovery of canine coronavirus in eight people at a hospital in Sarawak, Malaysia, was reported in Clinical infectious diseases by a group of highly regarded international scientists. Does it mean, then, that dogs can transmit coronaviruses to humans?
The first thing to clarify is what canine coronavirus is. It is important to note that it is 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 beta-coronavirus group, while canine coronaviruses are in the completely separate alpha-coronavirus group.
Scientists have learned about canine coronaviruses almost 50 years. These viruses have existed in relative darkness for most of this period, only of interest to veterinary virologists and occasional dog owners. There are no previous reports of these viruses infecting people. But the sudden international focus of all coronaviruses is to find coronaviruses in places we hadn’t seen before.
Canine coronavirus infections recently identified in humans were serendipitally discovered. Scientists were not specifically looking for canine coronavirus and the patients involved had long since recovered. The researchers were trying to develop a new test that could detect all types of coronavirus at once, the so-called pan-CoV test.
After confirming that the test worked on virus samples grown in laboratories, they did so tested it on 192 human swabs of pneumonia patients hospitalized in Malaysia. Nine of these samples tested positive for coronavirus.
Subsequent analysis showed that five of the nine samples were normal human coronaviruses that can cause colds. But, surprisingly, four of the samples were canine coronavirus. A subsequent study of patients from the same hospital revealed four more positive patients.
The researchers studied nose and throat swabs from the eight Malaysian patients to try to learn more about canine coronaviruses. Samples were placed in the canine cells of the laboratory to see if there was any live virus. The single-sample virus replicated well and virus particles could be seen by electron microscopy. Scientists were also able to sequence the virus genome.
The analysis found that this canine coronavirus was closely related to a few different alfacoronaviruses, including those of pigs and cats, and showed that it had not been previously identified anywhere else.
There is no evidence of subsequent spread
Was canine coronavirus responsible for pneumonia in patients? At the moment, we just don’t know. Seven out of eight patients became infected simultaneously with another virus, either adenovirus, influenza, or parainfluenza virus. We know that all of these viruses can cause pneumonia on their own, so they are more likely to be responsible for the disease. We can say that there is an association between canine pneumonia and coronavirus in these patients, but we cannot say that it is the cause.
There have been concerns that the canine coronavirus identified in these Malaysian patients could spread from person to person, leading to a wider outbreak. What many headlines do not clarify that these human infections actually occurred in 2017 and 2018. This makes the likelihood of a canine coronavirus outbreak from this source even lower, as there is no evidence of subsequent spread in all three or four. following years.
As coronaviruses have become the focus and we look for related viruses, we will inevitably find more positive samples in unexpected places. The vast majority of these will be of academic interest only and will not need to be alarmed. However, it is critical that surveillance of new coronaviruses continue and expand so that we have the best possible chance of identifying significant jumps between species in the future.