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Measles infections have been identified in two young Hennepin County siblings who recently returned from international travel.

The first case emerged in a 5-year-old child, who developed a characteristic measles rash on June 7, and later in the child's sibling. One of the children was hospitalized because of complications from the infection.

Minnesota health officials announced the cases of the vaccine-preventable illness on Tuesday but said the risks to the broader community were low. Neither of the unvaccinated children was believed to be infectious during travel, and both were isolated from others after showing symptoms. Health officials said the children had traveled to a country where measles is common but did not specify the country.

The Minnesota Department of Health nonetheless issued an alert for physicians to watch for telltale measles symptoms through July 1 and to know when to prescribe prophylactic treatments to people who have been exposed to the highly infectious virus. Health care workers in contact with the children were being notified of their exposure risks.

The department also announced the cases as a cautionary tale over Minnesota's slipping rate of childhood vaccinations. The share of 2-year-old children who received at least one dose of the measles vaccine dropped from 81.4% in 2019 to 79.3% in 2021, according to state health immunization data.

"As long as there is measles somewhere in the world and people travel, the risk to Minnesota remains," said Margaret Roddy, the health department's section manager for vaccine-preventable disease. "The measles vaccine is safe and effective. Without it, the risk of disease is real."

Measles typically results in fever as a first symptom, followed by a red, spotty rash and cold symptoms. Severe and even fatal illness can occur. No specific treatments exist other than common fever-reducing medications and basic supportive care.

Preventive care involves taking the measles vaccine within three days of viral exposure or immune globulin shots within six days to boost the immune system's response to infection.

Minnesota has had four cases of measles since 2017, when an outbreak of 75 cases mostly involved unvaccinated Somali children and preschool facilities. While the measles virus is largely contained in the United States through vaccination, it is one of the most infectious agents on the planet.

One person infected with measles would be expected without interventions or vaccinations to spread the virus to 16 to 20 other people. By comparison, health officials were concerned when the original COVID-19 coronavirus emerged that one person could spread the virus to two or five others.

People with measles can become infectious four days before or after their rashes appear, and they can spread the virus by coughing, talking or breathing in the same room with others, according to the health department. Minnesota had an outbreak of 16 measles cases in 1991 that originated at a Special Olympics ceremony at the Metrodome. The virus in that outbreak spread from someone on the field to others higher up in the stands.