The United States has recently recorded 58 cases of measles in 17 states, including Virginia. That should be a wake-up call for parents and health officials across the country. Children who weren’t vaccinated over the last few years are vulnerable to potentially serious — even deadly — diseases once considered gone for good.

The World Health Organization is calling for action to protect children by bringing their immunizations up to date. Otherwise, WHO officials say, more than half the world’s countries could be facing measles outbreaks by the end of the year.

That includes the United States, even though the federal Centers for Disease Control designated the disease eradicated in 2000. The resurgence in Florida shows how easily diseases we considered conquered can resurface, often spread by international travel.

These diseases should not be taken lightly, even though many of today’s parents have no experience with them. Measles, a highly contagious airborne virus spread by coughing or sneezing, can live on surfaces and in the air for hours.

There is no known cure, although fever reducers and other medications may help. Measles attacks the respiratory tract and spreads throughout the body, causing high fever, cough and a rash. Possible complications include pneumonia, the most common cause of measles-related deaths among young children, and swelling of the brain, leading to convulsions, permanent hearing loss or intellectual disabilities. It can also cause blindness.

Measles also can be dangerous for adults with compromised immune systems and may cause unvaccinated pregnant women to give birth prematurely.

Americans thought we had the problem licked, thanks to an aggressive vaccination program for young children starting when a vaccine was developed in the 1960s. In 1971, the measles vaccine was combined with vaccines against mumps and rubella. Children were given one shot of the MMR vaccine, followed by one booster. In 2005, a vaccine for chickenpox (varicella) was added for an MMRV vaccine for children ages 12 months to 12 years.

The vaccines work. The CDC says two doses of MMR vaccine are about 97% effective in preventing measles; one dose is about 93% effective. Before the vaccine, about 500,000 cases of measles were reported annually in the United States. An average of 400-500 patients died. Widespread use of the vaccine reduced measles cases by 99%.

But measles is back. Medical experts say 95% of the population needs to have been vaccinated against measles for herd immunity to protect the unvaccinated 5%. In the 2021-2022 school year, the CDC reports, that vaccination percentage had dropped to 93% of kindergartners.

Some people can’t be vaccinated because of allergies or other medical reasons. Unfortunately, in recent years, many states have made it easier for parents to skip children’s vaccinations on religious or other grounds.

COVID is a major factor. Health care was so disrupted by the pandemic that many young children missed routine vaccinations that had become routine. Many still aren’t up to date.

There’s growing skepticism about vaccinations and science in general. Misinformation is rampant, some spread by people who sincerely (if mistakenly) believe that vaccines are dangerous, some by people who think spreading fear will help them politically or financially.

In Florida, Joseph Lapado, the state surgeon general, told school officials that parents should decide whether their unvaccinated children stay home for 21 days during a measles outbreak, even though letting them go to school puts them at risk of infection, serious complications and even death. Lapado expressed concern about missing school and claimed they’d be protected through herd immunity, though Florida’s vaccination rates are too low to make such a promise.

It took a lot of years, work, leadership, strong government policies and communication to get to the point where measles could be considered eradicated in the U.S. It’s taken a lot less time to slide back.

Make no mistake: The trend away from using vaccines that can protect children from measles and other potentially serious diseases is a health time-bomb ticking away. Action is urgently needed.