Mumps Infection Despite Vaccinatio

Posted by Judy Arbique Sep 10, 2006

Although mumps vaccination programs began in the mid-1970's, recent outbreaks of mumps have occurred locally in the Halifax area of Nova Scotia, as well as in the U.S., and the United Kingdom.

For any of us old enough to actually remember having mumps as a child, the image of chipmunk cheeks is likely the memory that remains. The most common symptoms of mumps infection are one or two-sided swelling of the parotid (salivary) glands, sore-throat and fever, but up to 20% of those infected may be asymptomatic. Mumps infection is usually self-limited, but occasionally may cause serious complications such as meningitis (15% of cases), encephalitis and permanent central nervous system damage, pancreatitis (4% of cases), deafness (1/20,000 cases), spontaneous abortion during first trimester of pregnancy (25% of cases), orchitis in postpubertal males (40% of cases) possibly resulting in infertility.

A report published in the Canadian Medical Association Journal (Two successive outbreaks of mumps in Nova Scotia among vaccinated adolescents and young adults)describes two recent outbreaks of mumps in Nova Scotia in August 2005 among vaccinated adolescents and young adults - one involving 13 high-school students, nine of whom had received 2 doses of MMR (measles-mumps-rubella) vaccine and 4 who had received a single dose. The second outbreak involved 19 cases of mumps in students and staff at a Halifax university - all but one of those infected had received only 1 dose of vaccine. The virus isolated from the first outbreak belonged to a genotype common in the U.K., while the virus from the second outbreak was similar to a strain associated with outbreaks in the U.S. and the U.K.

Recent mumps outbreaks in the U.S. included 31 cases among staff and campers at a summer camp in New York, and an outbreak originating in Iowa in December 2005, and involving at least 10 more states as of May, 2006. The source of infection in the New York summer camp was a 20-old camp counselor from the U.K. who had not been vaccinated. During January 1 - May 2, a total of 2,597 mumps cases were reported, with the majority of these in Iowa (57%), followed by Kansas (14%), Illinois (9%), Nebraska (8%) and Wisconsin (7%). Cases also occurred in Missouri, Pennsylvania and South Dakota. Additional cases in Colorado, Minnesota and Mississippi were associated with travel to an outbreak state. Although vaccination data collection is incomplete, it would appear that the majority of those infected in the Iowa outbreak had received 2 doses of MMR vaccine (51%). (Morbidity Mortality Weekly Report).