Public health officials said Thursday that they're investigating a seventh confirmed case of measles among Los Angeles County residents amid an outbreak of the highly contagious virus.
Officials had previously said those four people were infected on an international trip. The other two patients in the county are not linked but also became sickened during a trip abroad, authorities said.
The sixth patient is not tied to exposures that prompted the quarantine of hundreds of students and staff members at UCLA and Cal State Los Angeles.
And, unlike the other cases, officials have not identified any public locations the seventh patient visited while infectious, so there is no known exposure threat.
In addition to the seven local residents who contracted the illness, authorities have identified five non-residents who traveled through L.A. County while infectious.
The majority of individuals sickened were not vaccinated, officials said. About 90% of unvaccinated people become ill seven to 21 days after exposure.
“We will likely see additional measles cases in Los Angeles County, so if you are not already immune to measles, the best way to protect yourself and to prevent the spread of measles is to get the measles immunization, with two doses of measles immunization being about 97% effective at preventing measles,” L.A. County Health Officer Muntu Davis said in a statement.
The U.S. is currently experiencing the highest number of measles cases since 1994, with more than 700 cases confirmed across the nation as of Monday, according to the Centers for Disease Control and Prevention.
That includes around 40 cases in California.
Measles symptoms include fever, cough, a runny nose and red eyes. A rash usually appears 7 to 21 days after exposure.
People who haven't been vaccinated and those with weakened immune systems are at the highest risk.
Anyone who is not vaccinated against the highly contagious illness should speak with their health care provider. People with measles can spread the virus before they know they are infected and up to four days before a rash begins to develop.
More information about the measles can be found by going to the L.A. County Department of Public Health website or dialing 211.