The number of measles cases in the country spiked by nearly 100 in the past week, reaching a high of 465, the Centers for Disease Control and Prevention (CDC) said Monday.
This is the second greatest number of cases reported in the U.S. since measles was eliminated in 2000, the agency said. The worst year for measles since then was 2014, when there were 667 cases.
Last week, the CDC confirmed 387 cases across 15 states, which was more than there were in all of 2018.
{mosads}This week there are cases in 19 states, and the outbreaks are linked to unvaccinated travelers returning to the U.S. from countries where large measles outbreaks are occurring, such as Israel and Ukraine.
Many of the cases are tied to one unvaccinated child from New York City. The initial child with measles was unvaccinated and acquired measles on a visit to Israel.
As of April 3, there have been 259 confirmed cases of measles in Brooklyn and Queens since October. Most of these cases have involved members of the Orthodox Jewish community.
Outbreaks can occur when someone infected with the measles returns to communities in the U.S. where there are high numbers of people who are unvaccinated.
Vaccine rates have dropped slightly in recent years, mostly among children, health experts say, due to the spread of misinformation online about vaccine safety.