Researchers in Ireland have detected "an alarming rise" in the number of young males suffering from testicular problems after being infected with mumps, once a common childhood illness.
They are urging doctors to provide the MMR shot (measles, mumps and rubella) to unvaccinated males between the ages of 15 and 25.
Before vaccinations became widely used, mumps primarily affected children aged five to seven, who became immune after the initial infection. When the virus strikes for the first time in adulthood or the teenage years, there is a greater risk of serious medical complications, including swollen testicles in males.
The lead researcher, Niall Davis of Mid-Western Regional Hospital in Limerick, Ireland, noted that there was a global shortage of the vaccine 15 years ago. At the same time, reports that the vaccine was linked to autism made some parents reluctant to have their kids vaccinated, especially in Britain. (The alleged autism link has since been discounted.)
"Boys who did not receive the ... 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 virus," Dr. Davis said in a statement issued with the study, published in the British Journal of Urology International.
"Our data reflects global trends and not just trends in Great Britain," he added in an e-mail. "Some of the countries in which epidemics have been described include Australia, the United States, Wales, England, Ireland and Switzerland," he noted. "There was also a small outbreak in Quebec in October 2009."
More than 40 per cent of patients infected with the mumps experience at least one complication, including swollen testicles, inflammation of the brain, pancreatitis and deafness. Swollen testicles can lead to "sub-fertility" and abnormal sperm for up to three months. Complete infertility is rare, Dr. Davis said.