Maybe there are fewer mumps cases in Wisconsin than health officials first thought.

State and federal officials say one test they've been using might not be accurate.

One mumps test is conducted on blood and serum and another on saliva.

But researchers say the serum test might give false positives, meaning the test could indicate the presence of mumps in people who don't have it. That would overstate the number of people infected.

Doctor Peter Shult says it's a nationwide problem, so there could be hundreds or thousands of wrong diagnoses -- or none at all.

Shult says officials are retesting results to know for sure.

Officials suggest people getting checked for mumps should take the more accurate saliva test.