By Glenn Howatt

Minneapolis Star Tribune

Three new measles cases were reported Wednesday by state health officials in an outbreak that has now sickened 24 children.

State officials said earlier this week that the current outbreak will likely exceed one in 2011, when 26 people developed the highly-infectious disease.

All the cases so far are in Hennepin County, in Somali-American children aged 5 years or younger. Investigations have shown that 23 of them had not received the measles vaccine; health investigators are obtaining records for the remaining child.

On Monday, state health officials urged Minnesotans to get current on their measles vaccinations if they have not previously had the disease. Parents of Somali-American children were also advised to speed up the measles booster shot, which is usually given around age 5.

Investigators have traced the current outbreak to several day care facilities in Hennepin County, but have not found the original source, believed to be someone who traveled outside of the United States. They have contacted families of children who were potentially exposed and have asked all who were unvaccinated to avoid exposing others.

That effort began two weeks ago, but since it can take three weeks for measles symptoms to develop, health officials expect more cases to emerge.

Measles symptoms often start out resembling a cold, with fever, cough, runny nose and watery eyes. After a few days, a rash begins at the hairline and spreads down to the rest of the body. In severe case, measles can produce lasting lung and brain damage.