Measles Outbreak Map Shows States Where Cases Have Been Reported

Cases of measles have been recorded in at least four U.S. states since the start of the year, as local health officials attempt to prevent the spread of the disease.

Officials in parts of Delaware, Pennsylvania, New Jersey and Washington have confirmed cases and are investigating whether others who had close contact with those infected with the illness may have contracted it as well.

It comes after officials in Virginia warned travelers that they may have been exposed to the virus which causes measles after they became aware of a person who had recently been in the northern part of the state following international travel. No cases have been confirmed in Virginia.

Measles is a highly contagious disease caused by a virus that spreads through an infected person's breath, coughs or sneezes. Symptoms tend to include cold-like symptoms and a rash of tiny red spots, but the illness can cause complications and, in some cases, lead to death.

On January 11, the Delaware Division of Public Health announced that 20-30 people may have been exposed to someone who had been at the Nemours Children's Hospital in Wilmington and was not showing symptoms of the disease but was infectious, on December 29, 2023. The incubation period for measles is usually about 10 days.

On January 13, the Camden County Health Department in New Jersey said it was "closely monitoring" a confirmed case of measles in the area, noting that potentially exposed individuals could develop symptoms as late as February 2.

The infected person visited Cooper University Healthcare Pediatrics in Voorhees between late morning and early afternoon January 5, and was in the emergency department of Jefferson South Jersey Stratford Hospital in Stratford between 8 p.m. January 8 and 12:30 a.m. the following day.

The person also visited a daycare center, but health authorities said those may have been exposed in the setting had been identified and contacted.

"Given the serious consequences of measles and the ease with which it can be spread, we will be engaged in a large investigative effort centered on locating and ensuring the immune status of those individuals who may have been in contact with this patient," said Paschal Nwako, a health officer for the county.

Health officials in Philadelphia, Pennsylvania, have been tracking an outbreak of measles in the city. As of Tuesday, there had been nine confirmed cases. The city listed locations—including several hospitals and a daycare center—where infections may have taken place across a number of dates from December 19 to January 7.

Camden County sits just across the river from Philadelphia, but health officials suggested to CBS News that it was unclear whether the case in New Jersey was linked to those in Philadelphia until more contact tracing had been undertaken.

Officials in Washington state said that, as of January 6, six epidemiologically connected cases of measles had been identified in Clark and Wahkiakum counties. They stressed that the risk to the public was deemed low and the infections likely occurred in mid- to late December.

"All six cases are unvaccinated," an announcement on the outbreak noted. The three cases in Clark County were among adults and had isolated at home.

Health officials in the U.S. urged people to get the MMR vaccine. One dose is 93 percent effective at preventing measles, while two doses are 97 percent effective.

According to figures compiled by the U.S. Centers for Disease Control and Prevention (CDC), between January 1, 2023 and January 4, 2024, there were 48 cases of measles reported in the U.S., 41 of which occurred in 2023.

The worst year for measles in the U.S. since 1992 came in 2019, when there were 1,274 cases recorded nationwide.

The disease was declared eliminated in the U.S. in 2000, but America could lose that status if an outbreak of more cases than the CDC expects from international travel were to occur for more than a year.