Teenage Boys and Young Men Who Lack Mumps Vaccinations Are at Risk for Reduced Fertility

From Medscape Medical News
Nancy Fowler Larson

March 31, 2010 — A reduction in mumps vaccinations in the 1990s has produced a spike in infections, raising concerns about fertility issues in men aged 15 to 24 years, according to an article published in the April issue of the British Journal of Urology International.

The introduction of the measles, mumps, and rubella, or MMR, vaccine in 1968 led to a sharp decline — 99% in the United States — in cases of mumps, a contagious viral disease. In the mid-1990s, the inoculation rate plunged in the United States, the United Kingdom, and other locations for 2 reasons: a global shortage of the vaccine, and publicity about its alleged, unproven connections to autism, inflammatory bowel disease, and Crohn's disease. In some parts of the United Kingdom, vaccination rates fell from 91% to 58%.

This failure to vaccinate had clear consequences. In 2001, confirmed cases of mumps hovered close to zero in England and Wales. By 2004, more than 56,000 cases were reported, according to the authors' examination of data spanning a 5-year period. As many as 40% of men who are infected with mumps experience 1 or more complications, including mumps orchitis, which can result in impaired fertility.

"This is of considerable concern as epidemics of mumps orchitis are now being reported more frequently in many countries worldwide," said Niall Davis, research registrar, Department of Urology, Mater Misericordiae Hospital, Dublin, Ireland, in a press release.

One case of mumps can result in 12 secondary infections in a vulnerable population. Today, many of the unvaccinated 15- to 20-year-olds are gathered in close quarters in secondary schools, colleges and universities.

"This clustered environment provides a perfect breeding ground for the virus," write Mr. Davis and colleagues.

Mumps orchitis typically appears 10 days after the disease's hallmark facial swelling, but it can occur up to 6 weeks later. Thirty percent to 50% of men with mumps orchitis, 1 or both testicles will atrophy, resulting in reduced size. Among other findings is the fact that complications can affect fertility even if swelling does not occur. For example, 13% of patients experience subfertility, whether or not they have had testicular atrophy, and up to 50% of patients produce abnormal sperm as long as 3 months after recovery — 24% of adults and 38% of teenagers can have abnormal sperm up to 3 years later.

The term "abnormal sperm" is used to reference sperm count, motility, and/or morphology. A significant relationship was found between the extent of testicular swelling and the degree of sperm abnormalities. The researchers found only a slight (incidence of 0.5%) association between mumps orchitis and testicular cancer.

The investigators call on physicians to become familiar with mumps and its complications and to recommend vaccinations for teenage boys and adult men who are not already inoculated.

"Clinicians should be aware of this epidemiological shift and of the resurgence of mumps orchitis," the authors write. "Unvaccinated male patients in this age group should be offered the MMR vaccine and educated about mumps orchitis and its potential complications."

The study authors have disclosed no relevant financial relationships.

BJU Int. 2010;105:1060-1065.