2nd measles death reported in US outbreak was in New Mexico adult

A second person has died from a measles infection amid an ongoing outbreak in the United States, health officials say.

The adult, in Lea County, New Mexico, tested positive for the measles virus, although the official cause of death is still under investigation, the New Mexico Department of Health said in a statement on Thursday (March 6).

As of March 6, there have been 10 confirmed cases of the virus in New Mexico, all concentrated in Lea County. It's unclear whether the new case is tied to the measles outbreak in Gaines County, Texas, but the two counties are about 50 miles (80 kilometers) apart.

Measles is a highly contagious virus that spreads from one person to another via droplets in the air — for example, through coughs and sneezes. It causes a respiratory infection and distinctive red rash, and it can potentially lead to more severe symptoms such as pneumonia and swelling of the brain, known as encephalitis, according to the Centers for Disease Control and Prevention (CDC).

About 1 in 5 cases requires hospitalization while approximately 3 in every 1,000 result in death, according to the New Mexico Department of Health.

As of Feb. 27, 164 confirmed measles cases have been reported in the U.S.this year, in Alaska, California, Georgia, Kentucky, New Jersey, New Mexico, New York City, Rhode Island and Texas, according to the CDC. The majority of cases have been reported in the South Plains region in northwest Texas, with 159 cases reported in total since late January as of March 4, according to the Texas Department of State Health Services.

Nationwide, 32 cases have resulted in hospitalization, and two people have died. The first fatality was of a school-age child in Lubbock, Texas.

Related: Death reported in Texas measles outbreak is 1st in US in a decade: What to know

Neither of the patients who died had been vaccinated against the virus, and 95% of the cases so far have been reported in those who are either unvaccinated or have an unknown vaccination status, according to the CDC.

A measles, mumps and rubella (MMR) vaccine is 97% effective at preventing measles, according to the CDC. However, breakthrough infections do occasionally occur, especially in communities in which high levels of the virus are circulating.

These breakthrough infections are usually milder, with only 3% of reported infections this year having been among individuals with one dose of the vaccine and 2% among those with two doses.

"We don't want to see New Mexicans getting sick or dying from measles," Dr. Chad Smelser, the deputy state epidemiologist at the New Mexico Department, said in the statement. "The measles-mumps-rubella (MMR) vaccine is the best protection against this serious disease."