Vaccination

After years of very few reported incidences in the United States, mumps very suddenly made a comeback in 2006, according to a study by the US Centers for Disease Control and Prevention recently published in the New England Journal of Medicine.

Mumps is a viral disease. The symptoms may be mild, with only a slight fever and a swelling of the salivary glands; it can also have effects as severe as encephalitis, inflammation of the testicles, and deafness.

In the period 2000-2005, mumps cases in the U.S. numbered less than 1 per million people. In 2006, there were 6,584 cases across the country. This translated into a national incidence rate of 2.2 per 100,000 people.

Interestingly, a huge concentration (85 percent) of mumps cases occurred in only 8 contiguous states in the Midwest, whose combined population was only 13 percent of the U.S. population.

The U.S. has set a target to eliminate mumps by 2010. The new outbreak may require a re-examination of the target. It may be necessary, said the authors of the CDC study, to develop more effective vaccines or to change the vaccination policy in order to achieve the goal.

Doctors usually consider disease-elimination programs successful if no new incidences or cases are reported within the country for at least a 12-month period.

It is still possible to achieve the target of eliminating mumps. But the study authors said that the disease may never be eradicated permanently, because over two-fifths (43 percent) of the countries in the world do not have a resolute vaccination program against mumps.

Starting in 1990, the U.S. implemented a 2-dose vaccination policy after a rash of mumps outbreaks affected both vaccinated and unvaccinated teenagers. From the time the 2-dose vaccination was required, mumps cases decreased dramatically.

A 2-dose vaccination is normally expected to be effective 88-95 percent of the time. The 2006 outbreak indicates that there was a failure of the 2-dose vaccine program in certain areas.

Slightly over three-fourths (76 percent) of the 2006 cases were detected during the March-May period. The most number of cases occurred among young adults aged 18-24 years. Incidence rate in this age group was 3.7 times the rate in all other age groups combined. More than 8 out of 10 of these patients were college students.

No single explanation could be postulated for the sudden outbreak. Many factors may have been involved, including high contact rates in colleges and insufficient immunity gained from the vaccine against wild mumps viruses.

Safety Tip:

* Vaccinate your children. There are parents who still refuse to have their children vaccinated, thinking that combined MMR (measles, mumps, and rubella) vaccine is unsafe. That puts their children at risk. The fears are without foundation.