A measles outbreak in the Fraser Health region has prompted a broader warning to residents and health professionals to be on the lookout for the disease.
Public health officials say four confirmed cases of measles have turned up in Burnaby, Surrey, Abbotsford and Chilliwack and several more patients have symptoms consistent with measles.
Fraser Health is investigating to see if the cases are linked.
So far there's no known source of exposure to measles – most infections are normally from travel to another country.
"These people haven't travelled so we really have no idea where they picked it up from," said medical health officer Dr. Michelle Murti, adding the new cases are unrelated to each other.
All the recent cases were either unimmunized, incompletely immunized, or didn't know their immunization status, she said.
Anyone born after 1956 should have two doses of measles-containing vaccine, although many have had just one or none at all.
The new cases in Burnaby and Surrey each had one vaccination, which Murti said underscores the case for getting two doses.
Advice and vaccinations are being offered to anyone who may have been in contact with those infected, and anyone who is unsure about their measles immunization can get the vaccine for free from doctors, clinics and some pharmacies.
There were three cases on Bowen Island or Whistler in June.
And in August Fraser Health warned that a measles-infected visitor to Abbotsford Regional Hospital exposed about 60 women and newborns in a post-natal unit.
The disease is most serious for infants, who die at a rate of one for every 3,000 infections in developed countries. It's much worse in the third world, which accounts for most of the 150,000 annual measles deaths worldwide.
The risk of fatalities as well as significant complications like pneumonia and brain inflammation is why health leaders encourage vaccination.
Measles are highly contagious starting one to two days before symptoms show up and continuing until four days after the classic measles rash begins.
The droplets from coughs and sneezes can remain airborne in a room for one to two hours after the infectious person has left.
"People can spread it without even knowing that they're ill," Murti said.
Anyone who develops measles symptoms – starting with a fever, runny nose, cough and red, watery eyes – is urged to stay home and not expose others.
Fraser Health has put up signs in its facilities warning that anyone arriving with those symptoms should advise staff immediately so steps can be taken to prevent infection of others.