Mumps is a contagious disease caused by a virus. It starts with a few days of fever, headache, muscle aches, tiredness, and loss of appetite, which can be followed by swollen cheeks (salivary glands) or swollen testicles in teenage boys and men. You can help protect yourself and your family against mumps with vaccination. The mumps vaccine is pretty effective; in general, one does of MMR prevents infection by 78%, and two doses up to 88%.
Mumps is no longer very common in the United States, but sporadic outbreaks continue to occur, especially in places where people have had prolonged, close contact with a person who has mumps. Before the U.S. mumps vaccination program started in 1967, about 186,000 cases were reported each year. Since the pre-vaccine era, there has been a 99% decrease in mumps cases in the United States. In 2012, there were 229 cases reported in the U.S.
We are kind of having an exciting year in regards to Mumps outbreaks; as of the end of December 2016, seven states have reported more than 100 cases: AR, IA, IN, IL, MA, NY, and OK. Washington is about to join that list with approximately 30 confirmed cases in King County and over 70 that are probable cases. Symptoms typically appear 16-18 days after infection, but there is a long incubation period ranging from 12-25 days after infection. Most people with mumps recover completely in a few weeks.
Mumps can occasionally cause complications, especially in adults. Complications include: inflammation of the testicles (orchitis) in males who have reached puberty, inflammation of the brain (encephalitis) or covering of the brain (meningitis), and inflammation of the ovaries (less obvious than the men.)
Here is where it gets interesting: the outbreak in Arkansas, Texas, and Washington State are predominately in Marshallese people, those individuals with heritage from the Marshall Islands. If geography is not your favorite subject, this is a group of Islands in the Pacific Ocean. 66% of those infected in Arkansas are Marshallese. 83% of those infected in Washington State are Marshallese or have close connections with the Marshallese community. Those with Mumps in Washington State are mostly school aged (5-18 years) and about 90% of that group is fully immunized.
So what does this mean exactly? Most likely the mumps portion of the MMR vaccine is less effective in the Marshallese population in particular due to some genetic difference in their immune response. It is also possible this virus is “drifting” by changing a protein here or there or an H or N molecule as similar to the influenza virus. So all in all, there are likely small changes in the natural mumps virus altering the landscape for everyone; however those with Marshallese background are naturally more susceptible.
In closing, as you would expect, I still recommend and support vaccination for all with MMR, personally and professionally. However, no vaccination is perfect and works 100% of the time. I wanted to share some scientific information with you all about what is happening here in the Northwest right now, most of which was provided by the Washington State Department of Health.