Japanese researchers say mumps-related hearing loss in children may be 20 times more common than previously suggested.
"Deafness is a rare but important complication of mumps virus infection," the researchers note in a report in The Paediatric Infectious Disease Journal.
They determined the incidence of sudden hearing loss in children with mumps based upon a population-based office survey of more than 7 500 patients from 40 paediatric practices in Japan, a country where mumps is endemic (constantly present).
Among 7 400 children who took hearing tests after the onset of mumps, seven, or 0.1%, had confirmed hearing loss. Hearing loss in the seven children was confined to one ear but was "severe and did not improve over time," the researchers note.
What the researchers found
"We were surprised so many people get hearing loss after mumps," said Dr Hiromi Hashimoto, from Hashimoto Paediatric Clinic in Osaka, Japan.
None of the seven children with mumps-related hearing loss had been vaccinated against mumps.
"I'm afraid many Japanese people, including physicians, don't know about mumps deafness," Hashimoto said.
"Many Japanese people believe mumps is a slight illness if only caught in childhood. We want many people to have a proper understanding about mumps and the importance of vaccination."
In a commentary on the Hashimoto's report, Dr Stanley A. Plotkin from the University of Pennsylvania, Doylestown, highlights the lack of universal mumps vaccination in Japan.
The absence of vaccination against mumps is "surprising for a developed country," Plotkin wrote, "and this regrettable policy must be changed for the sake of Japanese childre.." - (Reuters Health, April 2009)
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