(NEXSTAR) – More than 300 cases of measles, one of the most contagious viruses in the world, have now been confirmed across more than a dozen U.S. states, the Centers for Disease Control and Prevention announced Friday.
The actual case count is likely higher. The agency said it’s aware of more “probable” measles cases that are still under investigation.
As of this week, the virus is now confirmed in three additional jurisdictions: Maryland, New York and Vermont. (Previously, measles had been identified in New York City, but not elsewhere in New York state).
The biggest outbreaks are in Texas and New Mexico, but there are also cases in Alaska, California, Florida, Georgia, Kentucky, New Jersey, Pennsylvania, Rhode Island and Washington.
Measles is airborne and spreads easily when an infected person breathes, sneezes, or coughs. The virus then spreads from the respiratory tract throughout the body, causing a high fever; runny nose; cough; red, watery eyes, and a rash.
The rash generally appears three to five days after the first symptoms, beginning as flat red spots on the face and then spreading downward to the neck, trunk, arms, legs, and feet.
Measles isn’t usually deadly, but it can have serious complications, especially for young children. Among kids with measles, about 1 in 20 develop pneumonia, which can be fatal. About 1 in 1,000 also suffers swelling of the brain called encephalitis, which can lead to convulsions, deafness, or intellectual disability.
One death related to measles has been confirmed in Texas, and another in New Mexico is under investigation.
Of the 301 known cases, 50 have required hospitalization. Most of the cases are impacting children, and the vast majority – 95% – of those infected were not vaccinated with the measles, mumps and rubella (MMR) vaccine.
The best way to avoid measles is to get the vaccine, health experts say. The first shot is recommended for children between 12 and 15 months old and the second between 4 and 6 years old.
People at high risk for infection who got the shots many years ago may want to consider getting a booster if they live in an area with an outbreak, said Scott Weaver with the Global Virus Network, an international coalition. Those may include family members living with someone who has measles or those especially vulnerable to respiratory diseases because of underlying medical conditions.
Adults with “presumptive evidence of immunity” generally don’t need measles shots now, the CDC said. Getting another MMR shot is harmless if there are concerns about waning immunity, the CDC noted.
The Associated Press contributed to this report.
