The Maine Center for Disease Control and Prevention reported the state’s first measles case in two years on Tuesday, adding Maine to the growing list of states affected by one the nation’s most severe measles outbreak in decades.

Maine is susceptible to infectious disease outbreaks because it has one of the nation’s worst vaccination rates for students entering kindergarten.

One case of measles involving a school-aged child was confirmed Monday in Somerset County, the state CDC reported.

“The child is vaccinated, did not have any serious complications, and is fully recovered from the disease,” the agency said in a news release Tuesday. “Maine CDC notified the facilities where potential exposure occurred and is working with them to ensure potentially exposed individuals are made aware.”

The agency released a list of locations – including Madison junior and senior high schools, Waterville Pediatrics and the emergency department at Redington-Fairview General Hospital – where people were potentially exposed at certain times of day from April 30 to May 6.

People who may have been exposed should review their vaccine history and monitor for symptoms, the CDC said.

“Those who are not immunized or do not know their measles immunization status should get vaccinated with at least one dose of measles, mumps and rubella (MMR) vaccine to protect from subsequent exposures,” the Maine CDC said. “Individuals who were exposed and begin to develop symptoms should contact their health providers for instructions before arriving at the providers’ offices or hospitals, to ensure precautions are taken to prevent further infection.

“If symptoms are consistent with the disease, testing may be performed to determine whether the individual is infected. Individuals without symptoms should not be tested.”

Measles cases in the United States hit a 25-year high through May 17, according to the U.S. Centers for Disease Control and Prevention, with 880 cases in 24 states. Because Maine’s case was reported after May 17, it has not yet shown up on the federal report, but once it does, measles will have spread to 25 states.

The measles outbreaks have been most acute among unvaccinated populations in Washington state and New York City. A majority of the cases have been contracted by people who have not been immunized, according to the U.S. Centers for Disease Control and Prevention. But about 3 percent of people, despite being fully immunized, are still susceptible to contracting measles. In general, if a vaccinated person gets measles, they will have milder symptoms than someone who is unvaccinated, the U.S. CDC says.

Meanwhile, the Maine House and Senate approved a bill that would eliminate all non-medical exemptions to school-required vaccines. The Senate approved the bill by one vote last week. It faces at least one more procedural vote before heading to Gov. Janet Mills’ desk. She has indicated she supports the measure.

The last reported measles case in Maine was one confirmed case in 2017. On April 2, the Maine CDC reported a measles exposure by a Massachusetts resident who had visited the Skin Clinic in Falmouth and the Maine Centers for Healthcare Endoscopy in Westbrook on March 27, but there have not been any reported cases in Maine from that exposure so far.

The measles outbreaks have spurred actions including mandatory vaccinations in New York City. Maine has one of the worst opt-out rates in the nation for schoolchildren entering kindergarten, at 5.6 percent in 2018-19.

There are pockets of dangerously low vaccination rates that make the return of preventable diseases more likely. Forty-three Maine elementary schools had at least 15 percent of parents forgoing vaccines for their children entering kindergarten by using non-medical philosophic and religious exemptions.

Measles is a highly contagious and dangerous disease, with symptoms that include a rash that can cover the entire body, fever, cold, cough, runny nose and red, watery eyes.

Dr. Laura Blaisdell, a Yarmouth pediatrician, said the bill in the Legislature will improve vaccination rates, which is crucial for a disease like measles, which can easily spread.

“It is so important, to have safe communities and safe schools, to have as many people vaccinated as possible,” Blaisdell said.

After an infected person leaves a location, the virus remains alive for up to two hours on surfaces and in the air. The incubation period is typically 10 to 14 days, but can be as long as 21 days. Measles is so contagious that over 90 percent of people who are exposed and not vaccinated or immune from having previously contracted measles will get the disease.

Measles can cause severe health complications that may include pneumonia, encephalitis, brain damage and possibly death.

In about one in 1,000 childhood measles cases, death can occur, and there’s a similar chance that children can become deaf or have permanent brain damage from the measles.

Before the measles vaccine became widely available in the 1960s, about 3 million to 4 million children in the United States contracted measles each year, with 48,000 hospitalizations and 400 to 500 deaths, according to the U.S. CDC. Measles was declared eliminated in the U.S. in 2000, but the disease has experienced a resurgence in recent years as more parents have opted to not have their children immunized.

Severe reactions to the measles vaccine are extremely rare – fewer than one time per every million doses given – according to the U.S. CDC. Myths that the measles vaccine is linked to autism has been debunked, and the 1998 article claiming a link retracted.