Minnesota public health officials have identified two more measles cases, including a troubling illness in an unvaccinated Dakota County child with no recent history of travel or known exposures to others who carried the fast-spreading infectious disease.

The absence of identified exposures means the measles virus is spreading beyond the view of state health authorities, said Jessica Hancock-Allen, infectious disease division director at the Minnesota Department of Health.

"Anytime we confirm a case of measles unrelated to travel that has no known source, it is worrying," she said Monday.

The child was infectious while at the central theme park inside the Mall of America from 5 to 9 p.m. on May 24.

Other visitors to the mall in that time frame should be watching for symptoms, the Health Department warned on Monday. Classic measles symptoms include an itchy, head-to-toe rash as well as fever, cough, runny nose and watery eyes.

Because the virus takes time to incubate, symptoms could emerge among these potential contacts between May 31 and June 14. Hancock-Allen said the child was mostly in the theme park but may have been in other areas.

"We're not totally sure where else they traveled throughout the Mall of America and, of course, measles is very, very infectious," she said. "That's why we are sending out a blanket warning."

The other case reported Monday involved a Washington County adult who was exposed to measles while on a domestic U.S. flight. Hancock-Allen said the state was still checking with the infected individual and child immunization records to determine if the person had been vaccinated.

The two-dose measles vaccine typically offers 97% lifetime immunity against infection, Hancock-Allen said, and also lowers the risks of contracting severe illness or spreading the measles to others.

One of the fastest-spreading infectious diseases on the planet, measles can spread through airborne transmission of droplets in a person's breath that can linger in the air for up to two hours. People can become infectious four days before their first symptoms.

Both infected Minnesotans are recovering at home, the health department said.

The new cases raise Minnesota's measles tally to four in 2025, one year after an outbreak that resulted in 70 infections — mostly among young, unvaccinated children from the state's Somali community.

Hancock-Allen declined to provide demographic information about either new case. She stressed that "measles knows no boundary, demographically or otherwise" when people aren't vaccinated.

An investigation into the source of the child's infection is ongoing. Extended interviews were able to link infections in last year's outbreak among children who initially appeared to have no connections.

"Every once in a while, we do see someone that remembers something that they forgot to share with us," she said.

Minnesota once had one of the highest vaccination rates in the country, but last fall it had one of the lowest rates of vaccination for measles among children entering kindergarten.

Anxiety among parents over the COVID-19 vaccines has spread to other vaccines, including the MMR vaccine that is highly protective against measles, mumps and rubella. The MMR vaccine is usually administered in two doses around 12 months and 4 years of age.

Nationwide, more than 1,000 measles infections and three deaths have been reported this year, largely among unvaccinated children, according to the Centers for Disease Control and Prevention. One outbreak in Texas has resulted in more than 250 cases.

"Measles spreads easily, and it finds those who are vulnerable," Hancock-Allen said.