Because it is so highly contagious, even a single case of measles is considered an outbreak by the Center for Disease Control.

So, San Juan Island, home to four confirmed cases in less than two weeks, is, by definition, in the midst of an “outbreak.” But for better or worse, the island is not alone, as similar or more widespread outbreaks have occurred recently in New York City and on the campus of Ohio State University, in Columbus.

“There’s one in California as well,” San Juan County Health & Community Services Director John Manning said. “And there’s an outbreak now in B.C. (British Columbia), south of Vancouver, and a couple of cases in Whatcom County linked to the ones in B.C.”

The public health department circulated an “exposure alert” March 31 after confirming that a San Juan Island man had the measles and had been in numerous public places over a five-day period. Exposure to the disease would have occurred in the afternoon and evening hours of March 21 to March 24 in downtown Friday Harbor, possibly at several restaurants, Cask & Schooner, China Pearl, The Bean, and at Kings Market on the afternoon of March 24. The incubation period for the disease is seven to eighteen days.

Since the initial alert, Manning said that another three cases have been confirmed. The outbreak, however, has been limited to family and friends of those infected by the disease, according to the health department.

A highly contagious respiratory viral disease, measles spreads easily when an infected person breathes, coughs, or sneezes. The virus remains in the air up to two hours even after an infected person leaves the room. Those exposed to the virus and that have not been immunized against measles are likely to become infected, according to the health department.

The disease can cause serious complications such as deafness and pneumonia in young children, pregnant women and people with compromised immune systems. Symptoms include high fever, runny nose, cough, red eyes, and a rash of tiny red spots that starts at the head and spreads to the rest of the body. They will be present up to three weeks after exposure.

The health department began holding immunization clinics in the wake of the initial alert. Manning said the number of people seeking vaccinations has slowed since the initial influx, but that calls from those seeking information remain steady. State health officials have helped to track the outbreak and follow up with those who may have been exposed, he said.

The measles vaccine is exceeding effective, Manning said, with a 95 percent rate of effectiveness with one dose and 99 percent with a second. More people may have been infected by the measles virus had it not been for an outbreak of pertussis, commonly referred to as whooping cough, in the islands two years, which prompted an overall surge in vaccinations.

“Our immunization rates go up and down, but its better now than it was a couple years ago,” Manning said,

The health department cautions: If you or your child, older than 12 months of age; has not received a dose of MMR vaccine, you should be vaccinated now. If you or your child are older than 12 months of age and have received one dose of MMR vaccine and it has been more than 28 days since that dose, you should receive a second dose. Most adults born before 1957 have had measles are considered immune.

For more info, contact your health care provider or public health, 378-4474.