There is a report of a mumps outbreak on the campus of Berkeley in California, with two confirmed cases and another suspected case of the vaccine preventable disease.
Although we have been hearing a lot more about the measles outbreaks lately, there have actually been two very large mumps outbreaks fairly recently:
- 2006 mumps outbreak with at least 6,584 cases in 45 states
- 2009 mumps outbreak with at least 3,502 cases in and around New York and New Jersey
Mumps is a viral infection that can cause parotitis, with swelling and inflammation of the parotid glands at the angle of the jaw. Other symptoms can include myalgia, anorexia, malaise, headache, and low-grade fever.
Of course, we worry more about the complications of mumps, which can include meningitis (15% of patients), orchitis (testicular inflammation), which can occur in up to 50% of postpubertal males and can lead to some testicular atrophy, and less commonly, pancreatitis, deafness, and encephalitis. And mumps can occasionally cause life-threatening infections.
Although a mumps vaccine is routinely given as part of the MMR vaccine, unfortunately, it is not 100% effective. Unlike some other vaccines, the mumps vaccine is only about 75 to 91% effective at preventing mumps. This is much less than the 99% effectiveness of two doses of MMR at preventing measles.
In fact, many of the patients affected by the 2006 and 2009 mumps outbreaks were in fact vaccinated against mumps.
Still, according to the CDC, "People who are not vaccinated against mumps have a higher chance of getting the disease and spreading the virus to others." For example, in the 2006 outbreak, 2 doses of the MMR vaccine were estimated to be 79 to 88% effective in preventing mumps. Even though a lot of vaccinated people got mumps, they were 9 times less likely to get mumps than unvaccinated people.
Hopefully the mumps cases at Berkeley will be isolated cases and won't turn into larger outbreaks like we have seen in 2006 and 2009.
Remember, making sure your child is fully vaccinated with the MMR vaccine is the best way to avoid mumps.