April 13, 2006 -- The current Midwestern mumps outbreak may partly stem from two passengers on commercial flights to and from Iowa, the CDC reports.
Those passengers have been diagnosed with mumps and were "potentially infectious" when they flew in and out of Iowa between March 26 and April 2.
During that time, the passengers took nine flights on two different airlines, states the CDC's Morbidity and Mortality Weekly Report, citing Iowa's public health department.
Six hundred five confirmed, probable, and suspected mumps cases had been reported to Iowa's public health department through April 12.
Mumps has also been reported in six neighboring states: Illinois (four cases), Kansas (33 cases), Minnesota (one case), Missouri (four cases), Nebraska (43 cases), and Wisconsin (four cases), according to the CDC.
No Fatal Cases, Cause Unclear
The Iowa patients were about 21 years old, on average. Their symptoms lasted for an average of five days.
"The reasons for this outbreak are under investigation," states the CDC.
While the CDC isn't blaming the entire outbreak on those two air travelers, the CDC's report shows that one of those travelers flew to Minnesota and the other flew to Missouri, two states where mumps has been seen.
The CDC is using a new software program to identify people on the flights in question who may have been exposed to the mumps patients. Mumps typically incubates for 14-18 days.
The CDC reports that one of the travelers flew Mesaba Airlines, a Northwest Airlines affiliate, from Waterloo, Iowa, to Minneapolis on March 26. She later picked up Northwest Airlines flights to Detroit and Washington's Reagan National Airport, returning to Waterloo, Iowa, on March 29.
That traveler was a 51-year-old woman who may have contracted mumps on an earlier visit to the Dominican Republic, according to news reports. The woman didn't know she had mumps when she took those flights, the Associated Press reports.
The other passenger flew American Airlines on April 2 from Tucson, Ariz., to Cedar Rapids, Iowa, by way of Dallas, Arkansas, and Missouri. That traveler was a young man returning from an Arizona vacation, according to the Associated Press.
Mumps is usually prevented by getting two regular doses of the measles-mumps-rubella (MMR) vaccine.
As of April 12, Iowa's public health department had investigated the vaccine records of 362 Iowa mumps patients, nearly three-quarters of whom had gotten at least one dose of the MMR vaccine.
According to Iowa's public health department, almost two-thirds of the 362 patients whose vaccine records have been checked had gotten two MMR doses, 10% had gotten one dose of the vaccine, 3% hadn't gotten any doses, and MMR status was unknown for 23% of the patients.
The mumps vaccine is about 95% effective, states the web site of Iowa's public health department. "This means out of every 100 people vaccinated, 95 will be protected. However, the vaccine will not 'take' in five people, and these people will remain susceptible to the disease," the site states.