Unvaccinated Boys at Risk of Mumps-Linked Testicular Problem

FRIDAY April 2, 2010 -- A new study reports a significant increase in the number of young males with a mumps-related testicle condition called mumps orchitis, which causes one or both testicles to swell and can lead to fertility problems.

The measles-mumps-rubella (MMR) vaccine should be offered to all unvaccinated males aged 15-24, and they should be educated about mumps orchitis, said Irish urologists who reviewed five decades worth of research and statistics.

After the MMR vaccine was introduced in 1968, the number of cases of mumps orchitis decreased dramatically worldwide. But vaccination rates started to decline about 15 years ago because of a global shortage of the MMR vaccine and media reports that it was linked to autism, inflammatory bowel disease and Crohn's disease.

Even though subsequent research found no such links, there's still widespread public concern about the MMR vaccine.

"Boys that did not receive the [MMR vaccine] during the mid-1990s are now collecting in large numbers in secondary schools and colleges, and this provides a perfect breeding ground for the [mumps] virus," Niall Davis, a urology research registrar, said in a news release. "It's estimated that as many as 40 percent of males who develop mumps after puberty can suffer from orchitis. This is of considerable concern as epidemics of mumps orchitis are now being reported more frequently in countries worldwide."

In their review, Davis and colleagues found that:

  • Up to 50 percent of mumps orchitis patients experience testicular atrophy, a reduction in the size of one or both testicles.
  • Infertility is rare, but reduced fertility occurs in about 13 percent of patients.
  • Three years after recovery, 24 percent of adults and 38 percent of adolescents can still have abnormal sperm counts.
  • The association between mumps orchitis and testicular cancer is weak, with an incidence rate of 0.5 percent.

The paper appears in the April issue of the urology journal BJUI.

More information

The Medlineplus Encyclopedia has more about orchitis.

Posted: April 2010


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