Kansas City reaches important milestone in its two measles outbreaks

Kansas City has reached an encouraging milestone in the two measles outbreaks that have been spreading in the metro area since early March.

It's been more than 21 days, or one full incubation period, since the last known public exposure. But Mary Anne Jackson, the director of the infectious disease division at Children's Mercy Hospital, said it's not yet time to relax.

“We do not say a measles outbreak is over until we get past two incubation periods. That’s 42 days, folks," Jackson said Friday during a presentation to health officials at the Kansas Infectious Disease Symposium in Olathe. "I think we still have a little work on our hands."

The Kansas measles outbreak started when an infant picked it up during a trip abroad and brought it back to a daycare in Johnson County.

It spread to 12 other people who either attend the daycare or work there, Jackson said. Most of them, including the initial case, were unvaccinated because they are infants under age 1. That's the age when the first dose of the measles-mumps-rubella, or MMR, vaccine is usually given.

The virus has since infected nine people who live in Miami County and Linn County, for a total of 22 cases, the most in Kansas since 1990.

Jackson said the type of measles virus in that outbreak is from Pakistan.

The Centers for Disease Control declared measles eliminated from the United States in 2000, but it's still prevalent in some other countries and people can carry it back to the U.S. and spread it among unvaccinated populations.

The measles virus that has spread on the Missouri side of the metro is from Guatemala, Jackson said.

A traveler brought it back to the Kansas City area and it has since infected 13 people — eight children and five adults — who live in Clay County and Platte County.

“There were three household clusters where vaccine-refusing was part of the issue (in that outbreak)," Jackson said.

Measles is highly contagious. In unvaccinated populations, about 90 percent of people who are exposed to the virus will get the disease. But with two doses, the MMR vaccine is estimated to be at least 97 percent effective at preventing it.

Jackson said it's too soon to determine just how many of the 35 total cases occurred in people who had no MMR vaccines, people who had one dose or people who were fully vaccinated with a second dose, which is usually given before kindergarten.

That's because in some cases it takes time for people who think they've been vaccinated to locate and produce their immunization records.

Measles begins with a high fever and respiratory symptoms like cough and runny nose before proceeding to the telltale red rash associated with the illness. People who think they might have it are encouraged to stay home except to seek medical care, and even then to call ahead so doctors' offices and hospitals can arrange to separate them from other patients.

Most people recover from measles, but it can cause potentially fatal complications such as pneumonia and, more rarely, encephalitis.

There are about 40 known sites throughout the metro where people might have been exposed to measles since early March.

The Missouri outbreak included exposures at South Valley Middle School in the Liberty Public Schools and Nashua Elementary School in the North Kansas City School District.

Students at those two schools who aren't vaccinated were held out of classes during the 21-day incubation period per state law. Spokespeople for those districts said they're all back in class now.

The last known public exposure in the Missouri outbreak was April 18 at St. Joseph Medical Center in south Kansas City. The last known public exposure in the Kansas outbreak was April 15 at a store called Tranquility Village in Mound City.

Because it has been more than 21 days since those exposures, anyone who was at those sites and has not taken ill by now is in the clear. So is anyone who was exposed when a person associated with the Missouri outbreak took a road trip through Iowa, Minnesota and Wisconsin from April 13-16.

Still, Jackson said parents and medical providers should stay vigilant. There might still be unknown cases and unknown exposure sites in the metro area.

“We still have a ways to go," Jackson said. "But it is encouraging.”

This story was originally published May 11, 2018 at 1:40 PM with the headline "Kansas City reaches important milestone in its two measles outbreaks."