Though measles had been eradicated in the US in 2000, the disease is expected to continue a nationwide spread primarily because of vaccine skepticism, the Centers for Disease Control and Prevention (CDC) has said.

Measles, one of the most transmissible diseases, has been found in recent weeks in some north-eastern US states, according to the CDC.

The health agency warned healthcare workers about an uptick in measles infections and urged them to be on alert for new cases.

An email from the CDC sent to healthcare workers last week said the agency was notified of 23 confirmed US cases of measles between 1 December 2023 and 23 January 2024.

Most of these infections were in children and teenagers who had not gotten their measles vaccines despite being eligible. So far, measles cases have been found in Pennsylvania, New Jersey, Delaware and the Washington DC area.

Taylor Nelson, a University of Missouri healthcare center infectious disease physician, said to the news station KRCG that measles would probably spread to the midwest and the west coast given the situation laid out by the CDC.

If measles cases are discovered, healthcare workers are asked to isolate patients, immediately notify local and state health departments, test patients with nose or throat swabs, and ensure all patients are vaccinated against the disease, especially if traveling internationally.

The CDC email said measles cases often originate from unvaccinated or undervaccinated people who travel internationally and then transmit the disease to others who are not vaccinated against the disease.

“The increased number of measles importations seen in recent weeks is reflective of a rise in global measles cases and a growing global threat from the disease,” the email said.

Although measles is highly contagious, vaccines are effective in preventing the disease, which has caused a surge in cases in Europe, according to the World Health Organization.

Measles became a national problem in the US in the early 1900s. But once a vaccine for the disease was created in 1963, the number of cases drastically reduced over the next few decades.

An effective nationwide vaccination campaign successfully saw the vaccine routinely given to people as they began school, and by 2000 the campaign had prevented continuous transmission.

But measles is spreading again because of a growing number of unvaccinated people.

Measles symptoms include fatigue, a runny nose, coughing, fever, red or watery eyes, and eventually a full-body rash. In some of the worst cases, measles can lead to death.

Those who have received at least one dose of the measles/mumps/rubella (MMR) vaccine are 93% protected against measles. But two doses are recommended for maximum protection.

Those who have already had measles at some point in their life are also protected against the disease.

Measles is especially dangerous for infants and young children.

Once measles is contracted, health experts say the disease must run its course since no antiviral treatment targeting the disease exists.