US Mumps spreads to Canada - MMR vaccine under close scrutiny

CTV reports Canadian officials are closely monitoring the the worst mumps epidemic in the U.S. since 1988 -- 9 Midwestern states are now reporting cases.

A travel advisory was issued on April 13th for Canadian travellers to areas most affected. In early April, doctors in Hamilton, Ont., west of Toronto, discovered a patient who developed the mumps after visiting Iowa.

Starting in Iowa and moving rapidly into 9 states the virus has affected about 1,200 young people. No deaths have been reported.

Of concern to experts, however, is that an unusually high proportion of those affected have previously received the two-dose vaccine that covers measles, mumps and rubella.

Investigators are trying to determine the cause of the anomaly.

Dr. Neil Rau, an infectious disease specialist, told CTV Newsnet,"We used to believe the vaccine was 95 per cent effective,"

"There may be something novel about this strain of virus that indicates this vaccine is not as effective as we once thought."

"It could also be that the vaccine works very well when you keep having the disease in your midst," Rao said.

However, he added, it's possible that people lose their immunity to the virus once the risks have been minimized through vaccination, and when it reappears, people aren't prepared to deal with it and the effect is amplified.

The virus is said to be identical to the strain causing an epidemic in the UK last year. More background on the US outbreak here

Here is a blog which makes some astonishing (unprovable and mysterious) claims about the Mumps Mid West outbreak and the hospitalization and isolation of people - which is an unusual step to take as it is usually dealt with at home.

Here is the previous post about the outbreak with lots more information.

Pic (c) Newsweek archive of an outbreak in the 50's in Wisconsin