The Seattle-King County Health Department says some people at Sea- Tac Airport may have been infected with measles from another traveler on March 26.
A woman in her 20s flew from Amsterdam to Sea-Tac (on Northwest Flight 33) and then continued to Portland (on Horizon flight 2243). After developing a rash, she returned to the Netherlands on March 29 where a blood test on April 4 confirmed measles.
Health officials say other travelers who may have been on the flights and in the airport on the 26th should be alert for symptoms and see a doctor if they become ill.
Measles is spread through respiration and is highly contagious—90% of people without immunity sharing a house with an infected person will catch it. Airborne precautions should be taken for all suspected cases of measles.
The incubation period usually lasts for 4–12 days (during which there are no symptoms). Infected people remain contagious from the appearance of the first symptoms until 3–5 days after the rash appears.
Complications with measles are relatively common, ranging from relatively mild and less serious diarrhea, to pneumonia and encephalitis, corneal ulceration leading to corneal scarring. Complications are usually more severe amongst adults who catch the virus.
The fatality rate from measles for otherwise healthy people in developed countries is low: approximately 1 death per thousand cases. In underdeveloped nations with high rates of malnutrition and poor healthcare, fatality rates of 10 percent are common. In immunocompromised patients, the fatality rate is approximately 30 percent.
Measles is a significant infectious disease because, while the rate of complications is not high, the disease itself is so infectious that the sheer number of people who would suffer complications in an outbreak amongst non-immune people would quickly overwhelm available hospital resources. If vaccination rates fall, the number of non-immune persons in the community rises, and the risk of an outbreak of measles consequently rises.