Health officials are warning an unusually high number of measles cases among children in the Twin Cities could signal an oncoming outbreak.
The Minnesota Department of Health has recorded 13 cases of measles among unvaccinated children in the metro area since June — that's several times higher than the one to four cases seen in a typical year.
While most of the children shared a history of travel to a country where measles is common, a recent case among a child with no reported travel history is heightening concern about the potential for an outbreak here in Minnesota.
Investigators are still working to determine how that child might've become infected with the virus, according to state health officials.
“The measles virus is highly contagious and very successful at finding people who are unvaccinated, even within groups of people who may be vaccinated,” said Dr. Ruth Lynfield, the state epidemiologist.
The health department is urging parents to make sure their children are up-to-date on childhood immunizations — including the measles-mumps-rubella (MMR) vaccine, which is proven to be safe and highly effective against the measles virus.
According to Jennifer Heath, the immunizations program director for MDH, communities need an overall vaccination rate of at least 90% to prevent large measles outbreaks.
“Even a small drop in the immunization coverage rate means there are thousands more children who could be vulnerable to disease because they are not vaccinated,” Heath said. “If the coverage rate in a setting like a childcare or school is significantly less than 85 or 90 percent, that’s an outbreak waiting to happen."
While most Minnesotans are vaccinated, Lynfield said it only takes one case of travel-associated measles to start an outbreak in a community with low vaccination rates.
According to MDH, most of the children in Minnesota who've become infected so far were isolated when symptoms started, "so exposures were limited to health care and family settings" and the risk to the general public from these cases is low.
Measles spreads easily by coughing, talking or being in the same room with someone who has measles.
Symptoms of measles include a high fever, cough, runny nose, and watery eyes followed by a rash that typically spreads from the head to the rest of the body. It generally takes eight to 12 days from exposure to someone with measles to the first symptom, which is usually fever.
The rash typically appears two to three days after the onset of fever, according to MDH.