* Outbreaks in Britain, Balkans and Moldova
* Third vaccine dose could improve immunity
By Michael Kahn
LONDON (Reuters) - Mumps has made a resurgence in parts of Europe in the past year with outbreaks in Britain, the Balkans and Moldova, health experts said Wednesday.
In England and Wales, cases of the disease had doubled to nearly 1,700 in the past three months compared with the last three months of 2008, health officials said.
Several European countries had also reported outbreaks in the past year, from 50 cases in Sweden to thousands of infections in the Balkans, said Kari Johansen, a vaccine expert at the European Center for Disease Control and Prevention.
In Britain, many cases were among older teenagers and young adults, too old to have been immunized when the routine mumps, measles and rubella (MMR) vaccine was widely introduced.
Only 12 percent of the sufferers in Britain were born after 1990, when the two-dose MMR shot became universal.
“As the susceptible group is quite large, we expected to see high numbers of cases to continue over the next few years,” Mary Ramsay, an immunization expert at Britain’s Health Protection Agency, said in an email statement.
The large number of people in institutions such as universities allowed the disease to spread more easily, she said.
Mumps is a viral disease that can cause mild fever and swollen glands. Severe cases can cause deafness, testicular inflammation and encephalitis, or inflammation of the brain.
The virus can often mutate, so that people who have had only one or even two doses of vaccine remain vulnerable, experts say.
A double dose of the vaccine is supposed to be 88 to 95 percent effective but many countries that provide the inoculation do not give two doses or have not been doing so for as long as countries such as the United States.
While many people might have missed the MMR shot because of their age, the virus was so changeable that even two doses of the old vaccine was not always enough to prevent outbreaks in places with good vaccination coverage such as Sweden, Johansen said.
A third dose would boost the body’s immune response and, in theory, could provide what was known as cross-protection against mutated strains, Johansen added, but stressed tests in people would be needed to confirm this.
“Scientifically, researchers are looking at the possibility of a third dose of MMR,” she said in a telephone interview.
The last major mumps outbreak was in the United States, where more than 6,000 people became infected in 2006 and many more would have been affected if not for wide vaccination coverage, health officials said.
The mumps increase, however, was not tied to fears the MMR vaccine could cause autism. While health experts say these worries are unfounded, many parents in Britain and other countries have refused to have their children vaccinated.
Reporting by Michael Kahn; editing by Maggie Fox and Jonathon Burch