A large majority of those who contracted measles – 41 – have not been vaccinated against the disease, said Clark County officials. One patient received a vaccine against MMR (measles, mumps and rubella), but the health agency refused to provide more details about this case "to protect the privacy of the patient".

Most Washington residents – 34 – are children aged 1 to 10 years old.

Clark County Public Health urges all people who have been exposed to an identified location and who think they have measles symptoms to call their health care provider before going to the medical office to develop a plan that avoids To expose other people in the waiting room, "said the manager. the agency said.

Washington is not the only state struggling with the disease. Officials from Harris County, Texas, including Houston, reported three measles cases on Monday, bringing to six the total number of cases in the state this year.

According to US Centers for Disease Control and PreventionAt least 10 states reported measles cases in 2019: California, Colorado, Connecticut, Georgia, Illinois, New Jersey, New York, Oregon, Texas and Washington.

In total, at least 79 cases have been reported in the country this year.

Two other outbreaks have also been reported this year, said the CDC, in the state of New York and in New York City. Health officials said these outbreaks occurred in observant Jewish communities.

According to the New York State Department of Health, at least 209 cases have been reported there since October: 64 in Brooklyn and 145 in Orange and Rockland counties last week.

Epidemics began when travelers to Israel and Ukraine came back with the disease. Large measles epidemics are underway in both countries.

"In a given year, more cases of measles may occur for one of the following reasons: increased numbers of travelers infected with measles abroad and introduced to the United States and / or spread of measles in American communities with pockets of unvaccinated people, "says the CDC website.

The measles vaccine – known as the MMR vaccine – is very effective. A dose is about 93% effective in preventing measles if you come in contact with the virus. Two doses are effective at about 97%.

Experts recommend that children receive the vaccine in two doses: the first between 12 and 15 months and the second between 4 and 6 years.

Chris Boyette, Susan Scutti and Elizabeth Cohen from CNN contributed to this report.