Feb. 11, 2010 - An ongoing mumps outbreak has sickened 1,521 people in New York and New Jersey.
"Patient Zero" was an 11-year-old boy who got infected with mumps during a summer visit to Great Britain. He came down with symptoms while at a summer camp for Orthodox Jewish boys; campers and staff then carried the disease back to their communities.
Nineteen people have been hospitalized; no one has died. Scores of people have developed complications, including 55 cases of swollen testicles, five cases of pancreatitis, two cases of meningitis, one case of temporary deafness, one case of Bell's palsy, and one case of inflamed ovaries.
The infections happened despite high coverage with the measles-mumps-rubella (MMR) vaccine. Among patients ages 7 to 18 -- the age group that had the most cases -- 85% of patients had received the two recommended MMR vaccine doses.
"Two doses of mumps vaccine is believed to be 90% to 95% effective," Gallagher tells WebMD. "But that means people can still get mumps. If the vaccine is 90% effective and 100 people are exposed to mumps, 10 will get the disease."
In the U.K., the source of the outbreak, MMR vaccination rates remain low due to fears that the vaccine might be linked to autism. The small, 12-year-old study that spurred those fears has been retracted by the journal that published it and disavowed by 10 of its 13 authors. The doctors who did not disavow the study have been rebuked by U.K. authorities and face revocation of their medical licenses.
The U.S. mumps outbreak is the worst since an 11-state outbreak sickened 2,597 people from December 2005 to May 2006.
Over three-fourths of the cases have been in males, as the outbreak is spreading mostly in Orthodox Jewish schools for boys. Fewer than 3% of the cases have occurred outside Orthodox Jewish communities, mostly in people with close community contact.
New York City -- mainly Brooklyn -- accounts for 44% of the mumps cases. An additional 24% are in Orange County, N.Y.; 20% are in Rockland County, N.Y.; and 10% are in four New Jersey counties. Although the summer camp was in Sullivan County, N.Y., the disease is not spreading there.
Because of continued spread, health authorities working with communities in Orange County are giving schoolchildren a third dose of the MMR vaccine. Gallagher says it will be two or three months before it's known whether the effort succeeded.
Mumps starts just like most other viral diseases, with fever, tiredness, muscle aches, and/or loss of appetite. The classic sign of mumps -- swollen salivary glands that make a person look like a chipmunk -- don't appear right away. About half of people infected with the mumps virus don't get noticeable symptoms.
When mumps symptoms do appear, they usually come 16 to 18 days after infection. Because infection can precede symptoms by up to 25 days, outbreaks are difficult to control.
In the days before the introduction of the mumps vaccine in 1967, huge waves of mumps spread across the nation every few years.
"It is believed the vast majority of the population was infected," Gallagher says. "It's not as infectious as measles, but it spreads very easily via respiratory droplets."
There is no specific treatment for mumps, which is why vaccination is strongly recommended. Complications of mumps are more common in people who already have reached puberty.
Swollen testicles, a complication called orchitis, can lead to sterility, but much more rarely than once was believed. Permanent deafness is another feared but relatively rare complication of mumps.
A report on the mumps outbreak appears in the Feb. 12 issue of the CDC's Morbidity and Mortality Weekly Report.