HANOVER — A cluster of measles infections tied to an international traveler who visited Hanover last month has grown to three and health officials on Tuesday provided a new list of Upper Valley locations where people may have been exposed to the highly contagious, but preventable disease.

Both a vaccinated Vermonter and an unvaccinated Granite Stater contracted measles while in Hanover last month, according to Tuesday news releases from the Vermont and New Hampshire health departments.

The two new cases are believed to be related to an international traveler who had visited Hanover from June 20 to 22 and subsequently tested positive for measles.

The international traveler was infectious during late June visits to Dartmouth College, the Hanover Inn, Hanover Scoops and Lou’s Restaurant and Bakery, the New Hampshire Department of Health and Human Services previously said. In addition, the individual took the Dartmouth Coach to and from Hanover from Boston’s Logan Airport.

On Tuesday, health officials warned the public of additional places in the Upper Valley where they may have been exposed to measles, this time through the unvaccinated Granite Stater:

■July 1, 1:30 to 3:30 p.m.: Peppermint Patty’s, 25 Road Round the Lake, Grantham

■July 1, 5:30 to 11:30 p.m.: Sierra Trading Post, 200 S Main Street, West Lebanon

■July 3, 9 to 11:30 a.m.: Dartmouth Co-op, 21 S Main Street, Hanover

■July 5, 9 a.m. to 12:30 p.m.: Dartmouth Co-op, 21 S Main Street, Hanover

■July 5, 11:45 a.m. to 6 p.m.: ClearChoiceMD Urgent Care waiting room, 410 Miracle Mile, Lebanon

■July 6, 8 to 10:30 a.m.: ClearChoiceMD Urgent Care waiting room, 410 Miracle Mile, Lebanon

■July 6, 9:30 a.m. to July 7, 1 a.m.: Dartmouth Hitchcock Medical Center Emergency Department, 1 Medical Center Drive, Lebanon

Both state health departments are encouraging people to make sure they are up to date on measles vaccination. Vulnerable populations include people who are not immune, such as those who have not previously been infected or fully vaccinated, as well as people with weakened immune systems, and infants who have not yet been vaccinated.

“The 2-dose measles vaccine provides lifelong protection in most people, and it is the best protection against measles and complications of infection,” Dr. Benjamin Chan, New Hampshire state epidemiologist, said in the news release from DHHS. “Anybody who is not vaccinated is strongly encouraged to talk with their healthcare provider about completing the vaccine series.”

Anyone who was exposed to measles and is not protected against measles from vaccination or previous infection, or is unsure about their immunity status is asked to contact the New Hampshire Division of Public Health Services at 603-271-4496.

People who have been exposed and are not protected from measles may benefit from preventative treatment such as vaccination or a measles antibody injection to lower their risk of developing measles, the DHHS release said. In addition, those who are severely immunocompromised, even if previously vaccinated against measles, may benefit from preventative antibody treatment. DHHS urges such people to contact their health care provider.

The Vermont Department of Health said in its release that there is “no ongoing risk of measles from this case in Vermont” and it is unrelated to another case of measles the department had reported in April.

Health Department epidemiologists determined that the Vermonter had been outside the state while infectious. The department has identified contacts in other states and shared that information with those states’ health agencies. The department is monitoring one Vermont contact.

DHHS is in the process of conducting community-exposed contact tracing, and DHMC is identifying employees who were potentially exposed, Cassidy Smith, a Dartmouth Health spokeswoman, said in an emailed statement.

The case in the Vermont was identified after New Hampshire health officials provided the Vermont Health Department with information about Vermont residents who may have been exposed to measles by the Hanover visitor.

Of those on the list, health officials identified one person who was experiencing symptoms. Symptoms of measles include: high fever, cough, runny nose, and watery eyes, which appear several days before a distinctive red-brown body rash. Measles also can cause serious health complications, especially in children under the age of 5.

Some people who become sick with measles also get an ear infection, diarrhea or a serious lung infection, such as pneumonia, Smith said. People who are exposed may develop symptoms up to 21 days, typically 10-14 days, after exposure. Severe cases are rare, but measles can cause the brain to swell and even result in death.

Public health nurses went to the Vermonter’s home on Sa turday to collect a specimen to be tested at the Public Health Laboratory. The results of that testing showed the person was positive for measles.

The measles virus spreads through the air and can remain infectious in the air for up to two hours after an infected person leaves a room. To prevent the spread of the virus, those who develop symptoms should call their health care provider before going to a health care facility. Masking also can help prevent the spread, Smith said.

Anyone exhibiting measles symptoms and/or who thinks they may have been exposed can call Dartmouth Health’s hotline at 603-650-1818, beginning on Wednesday.

Nora Doyle-Burr can be reached at ndoyleburr@vnews.com or 603-727-3213.