As a multi-state measles outbreak in New England has grown to include five infections, public health officials in Massachusetts and New Hampshire said Thursday they are tracking confirmed cases and possible exposures.
Massachusetts state officials announced the first confirmed case of measles in the state in more than four years and urged state residents to make sure they have been vaccinated against the highly contagious, airborne disease.
An alert from the New Hampshire Department of Health and Human Services also issued Thursday warned that people who visited three particular locations earlier this month in that state might have been exposed to someone with the infection.
That person, a traveler from out of state, visited Baked and Brewed Café in Alton and Texas Roadhouse in Concord on July 5 in the afternoon, then visited the Common Man in Merrimack on July 6 in the afternoon, according to the New Hampshire announcement.
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The Massachusetts case was diagnosed in early July in an adult resident from Worcester County who recently traveled internationally.
Spokespeople for public health agencies in New Hampshire and Massachusetts did not immediately respond to a request to confirm whether the case in Massachusetts had been linked to the outbreak affecting residents of New Hampshire and Vermont.
The New England cases come against a backdrop of surging measles cases in parts of the United States and Europe. The United States reported 13 outbreaks so far this year, compared with four in all of 2023, according to the US Centers for Disease Control and Prevention. In Europe, public health officials have warned that the total number of reported cases was on the cusp of surpassing all recorded cases in 2023. More than half of those who contracted the disease in Europe in 2023 were hospitalized, according to the World Health Organization.
The five infections listed in New Hampshire’s updated tally ― which does not specify where the three non-residents are from ― have all been traced to an international traveler who was diagnosed late last month, shortly after returning home from a visit to Hanover, N.H.
New Hampshire officials announced June 28 that the traveler had visited Dartmouth College and local businesses before riding a Dartmouth Coach bus from Hanover to Boston Logan Airport on June 22 to fly home.
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Massachusetts officials alerted the public on June 29 that the international visitor who had been in Hanover, N.H., traveled through Boston on public transit during their return trip to Amsterdam on June 22 while infectious with measles. The bus arrived at the airport at about 2:40 p.m., and the traveler was in Terminal E until about 8:40 p.m., officials said.
The number of confirmed cases grew to a cluster of three on July 9, when officials in Vermont and New Hampshire announced that one resident from each state had gotten sick, likely as a result of being exposed to the traveler in the Hanover, N.H., area.
Measles is among the world’s most contagious diseases, easily spread through the air. Its “reproductive rate” — the number of unvaccinated people that a single individual with measles can infect — is between 10 and 15, compared with an average of two people for COVID-19 before vaccines became available, said Dr. David Hamer, a professor of global health and medicine at the Boston University School of Public Health who also directs a travel clinic at Boston Medical Center.
Individuals who have received two doses of the measles vaccine are close to 100 percent protected and have close to lifelong immunity, Hamer said. In Massachusetts, vaccination rates are high, which makes an outbreak here less likely.
Some 96 percent of children in Massachusetts have received at least one dose of the vaccination, according to the American Academy of Pediatrics.
The most recent National Immunization Survey showed Massachusetts ranks number one in the country for 19-to-35-month-olds vaccinated with the measles, mumps, and rubella vaccine, DTaP vaccine for diphtheria, tetanus, and pertussis, and the combined series of seven vaccines recommended for children before they turn two.
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The explosion of new cases in Europe is being driven in part by an increase in the same kind of vaccine hesitancy that has been rising in parts of the United States, Hamer said.
“With more vaccine hesitancy and less coverage because of the pandemic, there’s a greater pool of people that are at risk for becoming infected,” Hamer said.
Measles is particularly dangerous for young children, who are at the highest risk of severe complications, with high rates of hospitalization and the potential to cause chronic weakening of the immune system that makes those infected more vulnerable to other diseases.
A prominent rash is usually the most visible symptom. Complications can include severe diarrhea, ear infections, and pneumonia. In a small number of cases, the disease can cause deafness, blindness, seizure disorders, and other brain diseases, according to DPH.
“DPH urges anyone who does not know their measles immunization status to contact their healthcare provider to get vaccinated with at least one dose of the MMR vaccine,” the statement read. “Health care providers who suspect measles should call DPH.”
As of July 11, a total of 167 measles cases had been reported in 24 jurisdictions across the United States, according to the CDC. About 84 percent were in individuals who were unvaccinated or had unknown vaccination status. Eleven percent had one dose of the measles, mumps, and rubella vaccine, and 5 percent had two doses. Nearly half of all reported cases (46 percent) were under 5 years of age. Among reported cases, 53 percent were hospitalized.
Adam Piore can be reached at [email protected]. Steven Porter can be reached at [email protected]. Follow him @reporterporter.