An infectious disease specialist in Toronto is trying to predict where new cases of a respiratory infection could crop up next.

The Geneva-based World Health Organization has encouraged countries to be on the lookout for NCoV, a coronavirus known to have infected 13 people in Saudi Arabia, Qatar, Jordan and the United Kingdom. There have been seven deaths.

Coronaviruses are a cause of the common cold but can also be the cause of more severe illnesses (Beth Fischer/Canadian Press)

Last week, WHO urged countries to consider molecular tests for the virus if someone has unexplained pneumonia or a severe respiratory infection that doesn't respond to treatment, particularly if the patient has recently travelled or come from affected countries.

Without a blood test to detect antibodies to the virus, cases can only be reliably determined using sophisticated and rapid diagnostic capabilities that may not be widely accessible in more resource-limited areas of the world such as South Asia.

"Our work has identified that about 50 per cent of all the travellers that leave Saudi Arabia, Qatar and Jordan end up going to resource-limited countries — low and lower income countries that don't really have robust public health and medical systems," said Dr. Kamran Khan, an infectious disease specialist and scientist at St. Michael's Hospital in Toronto.

"Being vigilant and really directing some of your resources to areas that have the highest risk, that is really going to offer you the greater potential of anticipating where this virus might show up and perhaps mitigate its impact."

In the U.K., a man who had recently travelled to Pakistan and Saudi Arabia became severely ill after his return. He tested positive for the coronavirus, as did two other members of his family who had not travelled abroad. Another female family member recovered after a mild illness, according to the UK Health Authority.

It's important to keep in mind that the total number of infections is unknown and the full spectrum of illness is unclear, Khan said.

"If there are a larger number of people with mild infectious they may go undetected," Khan said. "They may still be capable of spreading the virus to others, but they may not necessarily come to the attention of public health officials and health providers."

If so, the mortality rate from the virus is lower than it currently seems.

The Public Health Agency of Canada is advising people travelling to areas with confirmed infections to seek medical attention if they develop symptoms that include difficulty breathing.

Coronaviruses are a cause of the common cold but can also be the cause of more severe illnesses. So far, all cases of the new coroanvirus have experienced flu-like illness — coughing, mucous, shortness of breath, malaise, chest pain and/or fever.

It is difficult to distinguish between symptoms of the new coronavirus and seasonal respiratory infections, said Todd Hatchette, director of virology and immunology at the QE2 Health Science Centre in Halifax.

"You really have to look for the key features that would suggest they're at risk for this particular virus and right now that's travel to an area where someone has been infected or attached to a cluster of the infections."

Hatchette and Khan agreed Canadians should not be alarmed. They suggest common-sense precautions such as staying home when sick and seeking general travel medical advice before leaving.

With files from CBC's Pauline Dakin