British Columbia has identified eight more presumptive cases of the novel coronavirus, including one involving a woman who has no recent travel history.

This is B.C.'s first apparent case of the COVID-19 virus spreading in the community. The woman, who is in her 50s and lives in the Fraser Health region, has not had contact with other coronavirus patients or people returning from disease hot spots.

She tested positive for COVID-19 after visiting her doctor with what she assumed was influenza. Provincial health officer Dr. Bonnie Henry said officials have launched a detailed investigation into how the patient was infected — a process she described as "disease detective work."

"There's likely at least one other person out there who has this disease or had this disease, and we need to find them," she told reporters at a press conference Thursday.

Four of the new cases were identified in the same household as another patient in the Fraser Health region who was identified last week, Henry said. They were already being monitored for symptoms and are living in isolation.

'Things are moving quickly'

Another two patients are a couple in their 50s and 60s have recently returned from travel to Iran, and the final new patient is a resident of Seattle who is visiting family in the Fraser Health region.

Henry confirmed that one of the cases is linked to University Canada West in Vancouver, which closed its campuses on Wednesday for three days of disinfection.

There have now been 21 positive tests for the coronavirus in B.C., including 13 linked to the outbreak in Iran.

At least four patients have recovered completely. Only one patient has required treatment in hospital — a woman in her 80s who is in critical condition in the intensive care unit at Vancouver General Hospital.

Henry said that travelling internationally has become risky as the virus continues to spread around the globe.

"We are seeing that things are moving very quickly and things can open up very suddenly," she said. "This is one of those years where I would shift my thinking to staying at home."

People who have recently returned from travel in Iran and China have been asked to self-isolate for 14 days on their return to B.C.

Henry said that implementing screening at the land border with Washington state would be of "limited effectiveness," but officials are closely monitoring the outbreak there, which has led to 10 deaths so far.

B.C. officials are reminding anyone who feels unwell to stay home from work or school and to call 811 or their health practitioner if they have symptoms of coronavirus such as a fever or cough.