‘Very contagious’ disease found in North Idaho wastewater. What to know
Measles has been found in wastewater in North Idaho.
“We believe that there is or was someone in the Coeur d’Alene area that was infected with measles,” Dr. Christine Hahn, an epidemiologist at the Idaho Department of Health and Welfare, told the Idaho Statesman on Monday.
It’s possible they were completely asymptomatic, she said. It’s possible they had a mild fever and a little rash and never sought the medical care that would have added their case to a map kept by the Centers for Disease Control and Prevention. It’s also possible that the virus was shed by someone traveling through from Montana, Washington, Canada or elsewhere. Maybe they went back to their hometown in another state and got tested and reported there.
There’s no way to know for sure, Hahn said.
The two states neighboring Idaho’s panhandle have each reported 10-49 cases so far this year, according to the CDC. But Idaho has had zero.
“Wastewater detection won’t be translated into reporting a case,” Hahn said by phone. “Right now, we really can’t say if this indicates one person or more than one person.”
The dashboard for WastewaterSCAN, a national wastewater monitoring system based at Stanford University, first reported measles in wastewater treated at the Coeur d’Alene Water Resource Recovery Facility on July 29. Then, on July 31, it reported higher levels of the virus in that wastewater.
Many communities in the state don’t even do that kind of testing, Hahn said. The city of Boise, which treats wastewater for itself, Garden City and Eagle, hasn’t detected the disease, according to the dashboard. It is the only other community in the state that tests its wastewater for measles.
The virus found in Coeur d’Alene’s wastewater is a wild type, a label used to distinguish between measles that is naturally occurring and the diminished form of measles in the vaccine, Hahn explained.
“You may be aware that the measles vaccine is a weakened, live virus,” Hahn said. “So if you get your measles shot, you might actually shed a little bit of that virus into the sewer system, and that would just show up as a vaccine strain, not as a wild type.”
She said people should consider checking whether they’re protected, especially parents who are gearing up to send their children back to school or people planning to go on a trip.
The vaccine for measles is very effective because it offers, in most cases, lifetime protection, Hahn said. Children are recommended to get two doses, once when they turn 1-year-old and once before they start kindergarten, at about age 4 or 5. Boosters aren’t needed. But if you can’t remember if you were previously vaccinated, it doesn’t hurt to get the two doses again just to be sure, Hahn said. Or, you could get blood drawn and an antibody test that will tell you whether you’re immune.
“Maybe those old immunization records are still hanging around somewhere in a drawer, and you can double check,” Hahn said. “If you’re going to go and international travel, or you are a health care worker, it is recommended that you have documentation.”
She said Idaho has imperfect data, but according to the annual National Immunization Survey, nearly 80% of kindergarteners in the 2023-24 school year were vaccinated, leaving about 20% unprotected.
If you think you might have measles, or have been exposed to someone with measles, and develop a fever or rash, public health officials recommend staying home, isolating yourself from others and calling your doctor or a health care provider.
Measles has been surging nationwide. The CDC reported on Tuesday the highest number of annual cases since the U.S. declared measles eliminated in 2000. Most of the cases are connected to an outbreak that began in a Mennonite community in West Texas and spread to New Mexico, Oklahoma and Kansas, The New York Times reported. The majority of the Texas and New Mexico cases have been among people who are unvaccinated, according to the Times.
Wastewater testing is a valuable public health tool because it can detect the presence of infectious diseases, like measles, before cases are even reported.
“I feel like it’s a signal,” Hahn said. “Measles is very contagious, and so the wastewater itself is just our canary in the coal mine, as it were, telling us that measles is in the community. It’s just one more reminder that measles is still out there circulating.”