COEUR D’ALENE, ID – After measles was detected in wastewater in Coeur d’Alene, Idaho health officials are encouraging medical providers to look for the disease.

Wastewater surveillance — a recently expanded public health tool that involves studying traces of diseases in sewage water — doesn’t necessarily mean officials will detect cases of the infectious disease they spot. But the detection suggests someone had measles in the North Idaho area.

Idaho health officials have not reported any measles cases in state residents this year, during the nation’s worst outbreak of the highly contagious virus in decades.

Idaho health officials believe someone in the Coeur d’Alene area was infected with measles, Idaho Department of Health and Welfare Epidemiologist Dr. Christine Hahn said in an interview. But officials aren’t sure whether they were traveling through the area, or if they even knew they had measles, she said.

“We think this is real. And we want to use it to say to people, ‘Hey, measles is in the area. Please check your immunity records. Consider making sure you’re up to date and your children are up to date on the measles vaccine,’” Hahn told the Idaho Capital Sun on Tuesday.

The measles virus was detected in Coeur d’Alene from a sample taken on July 29, the Panhandle Health District announced last week.

The health district did not know of any suspected or confirmed measles cases in its area in North Idaho, but encouraged medical providers to consider measles as a possible diagnosis for people who have similar symptoms, according to the health alert issued Aug. 1.

What to do if you’re exposed to measles

The virus’s serious complications can include pneumonia, encephalitis and, in rare cases, death. A high fever, cough, runny nose, rash and red, watery eyes are common measles symptoms, the Centers for Disease Control and Prevention, or CDC, says.

There is no antiviral treatment for measles, according to the CDC.

People with measles symptoms should not enter health care settings without calling ahead, and should contact their health care providers. People exposed to measles should monitor for symptoms for 21 days after exposure.

Vaccination is the best measles prevention, officials say. But Idaho has a spotty vaccination rate

Measles — which can live in the air up to two hours after someone infected leaves — is highly contagious but rare. Up to 90% of non-immune people in contact with an infected person can become infected.

Vaccination is the best way to prevent measles, health officials say.

Idaho has the lowest rate of kindergartners — nearly four out of every five — who are reportedly up to date on their measles vaccine, according to CDC data.

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On average, nearly 91.6% of kindergartners across the U.S. are up to date on their measles vaccine, compared to 78.5% of Idaho kids, the data show.

But a separate CDC vaccine survey found a higher measles vaccination rate for young Idaho kids, estimated at 88.7%.

And some of the one-fifth of Idaho kindergarteners without confirmed vaccination rates might be vaccinated, Hahn told the Sun.

Idaho has the highest opt out rate for school vaccine requirements, with 14% of parents opting their kids out compared to just 3% nationally, Idaho Education News reported.

“Those parents that are saying ‘I’m exempting my child from this requirement,’” Hahn said. “That doesn’t necessarily mean they’re unvaccinated. … We can’t exactly call it a (vaccination) rate for that reason.”

The United States’ worst measles outbreak in decades

The United States is experiencing its worst outbreak of the highly contagious measles virus in decades, Stateline reported. This year, health officials have confirmed 1,333 measles cases across 40 states by late July, the CDC says.

In 2000, measles was declared eliminated in the U.S. thanks to vaccines.

In May, South Central Public Health District reported that a visitor to Idaho had measles.

Idaho has not reported cases of state residents with measles since 2023, when an outbreak in southwest Idaho led to 10 measles cases, Hahn said. The outbreak started with an Idaho resident exposed during international travel, she said.

Idaho Capital Sun is part of States Newsroom, a nonprofit news network supported by grants and a coalition of donors as a 501c(3) public charity. Idaho Capital Sun maintains editorial independence. Contact Editor Christina Lords for questions: info@idahocapitalsun.com.