A measles outbreak first detected two months ago continues to spread through the Fraser Health region, an area in southern British Columbia that contains 1.6 million people and extends from Burnaby to Hope.
Tracing back from the seven patients who have so far been detected with the highly infectious disease, health authorities have identified hundreds of people who might have been exposed – but they have failed to detect the original carrier.
"What's been a little frustrating to us is that typically measles in Canada is through importation from other countries," medical health officer Michelle Murti said Thursday. "And so far we haven't been able to find the original [source] from where our cases have been exposed."
She said the most recent case, detected Friday, involves a three-year-old girl, but it isn't known yet how she came in contact with the disease.
"We're still trying to figure out what cluster this belongs to and what this case means in terms of ongoing transmission risk to the community," Dr. Murti said. "Measles is a highly infectious disease. It's an airborne spread so even people who were sitting in the same room up to two hours after [a carrier has left] can come in contact with the virus and become infected. It's one of the most highly infectious diseases that we have."
Last month, Fraser Health issued a directive to all staff, including physicians, midwives, dentists and volunteers, saying they had to show proof of immunization against measles if they want to continue to work in public-health facilities. A health alert was also sent advising staff to isolate anyone arriving at hospital with the symptoms of measles, which include fever, cough, runny nose and inflamed eyes.
Last week a directive was sent to B.C. Ambulance Service employees in the Fraser Health region saying they could not work without proof of immunization. Bronwyn Barter, president of Ambulance Paramedics of B.C., said the union is supporting the call for immunization, but questions the blanket coverage sought by health authorities.
"We think it's important to protect not only our paramedics, but their families, the public and our patients," she said. "But we also support a person's right to choose. Obviously, some can't get the vaccination because of a pregnancy or some other underlying medical issue."
Ms. Barter said the measles outbreak is "an added stress" on the job for paramedics because in the early stages of the disease it is difficult to tell who has it.
Measles is a respiratory system infection that in extreme cases can lead to brain inflammation, blindness and deafness. One in about 3,000 cases is fatal.
The B.C. Centre for Disease Control on Tuesday issued a statement urging parents to make sure their children participate in school-based immunization clinics this fall.