According to the CDC, the mumps outbreaks in 2016 is worse than it has been in the last ten years. The latest Morbidity and Mortality Weekly Report, mumps cases in 2016 thus far tally 3,832, which is triple the 1,088 cases that occurred in 2015. The virus has emerged across the country, but Arkansas has a third of the total cases at 1,305. Iowa reported 645 cases, Illinois reported 377, and Indiana reported 231. There were also outbreaks in New York and Massachusetts.
University of Missouri is limiting dining hall hours and social gatherings, as it has had 128 cases this semester. All of the infected students had received the MMR vaccine. Why were they then still susceptible to the infection? The memory arm of the immune system can often need booster vaccines to bring up the level of circulating antibody for the virus, so that it can continue to mount an effective defense in case of infection. In the case of mumps vaccine, the effectiveness of the vaccine increases from the 1st dose to the second dose, from 78% to 88% effectiveness.
The easy spread of mumps among university students is likely due to the nature of dormitories, which facilitate close contact and transmission of the virus. The virus can be transmitted through respiratory droplets (coughing/sneezing/talking) or through saliva.
Mumps is caused by rubulavirus, paramyxovirus that causes swelling of the salivary glands, as well as typical viral symptoms such as fever, fatigue, headache, and anorexia. Complications include encephalitis, aseptic meningitis, acute pancreatitis, and orchitis (testicular inflammation), Guillain-Barré, and several other complications related to inflammation.
"Mumps: For Healthcare Providers."http://www.cdc.gov/mumps/hcp.html
"Morbidity and Mortality Weekly Report (MMWR): Notifiable Diseases and Mortality Tables." December 2, 2016. http://www.cdc.gov/mmwr/volumes/65/wr/mm6547md.htm?s_
"Mumps Outbreaks Are Worst in a Decade." December 5, 2016. http://www.wsj.com/articles/mumps-outbreaks-are-worst-in-a-decade-1480968263