As Measles Cases Surge, Mexico Issues a US Travel Alert

As the US struggles to contain its worst measles outbreak in years, cases have spilled over into Mexico. In an April 25 report, Mexico’s Ministry of Health reported there have been 583 confirmed cases in the country this year, with 560 recorded in the border state of Chihuahua. On April 27, the Chihuahua Health Secretariat pushed the state’s number of confirmed cases even higher, to 713. In comparison, the Pan American Health Organization reported only 7 confirmed cases in the whole of Mexico in 2024.

The outbreak in Chihuahua is partly due to its proximity to Texas, which it borders to the north. A major outbreak has been ongoing in the US state since late January, and cases in Mexico have been linked to those north of the border. The United States has recorded 884 confirmed cases of measles this year, up from 285 in 2024, as well as three deaths from the disease. Of this year’s cases in the US, 646 have been in Texas.

To try to prevent the measles virus from spreading further throughout Mexico, its Ministry of Health has issued a travel warning for the United States and Canada, where cases have also risen sharply. The ministry advises travelers to make sure they are up-to-date with their vaccinations, practice social distancing, wear a mask, and frequently wash their hands.

Falling vaccination levels have also helped drive up Mexico’s cases, as they have in the US. In 98 percent of US cases this year, the patient—whether an adult or child—had no history of vaccination against measles. In early April, it was reported that a 31-year-old man unvaccinated against measles had died of the disease in Chihuahua.

Because measles is highly contagious, very high rates of vaccination against it—95 percent—are needed across communities to stop the virus from spreading. But rates of vaccination in Mexico have been faltering. Children are supposed to receive two doses of the measles vaccine, the first typically between 12 and 15 months, and the second within the next few years. According to the WHO, in 2023 only 76 percent of children under 2 years old in Mexico had received a measles vaccine.

If rates don’t improve, this could allow the disease to become endemic again in North America. According to an analysis by Stanford University epidemiologists, at current state-level vaccination rates in the US, measles could reestablish itself and be steadily present in the country over the next two decades. This would result in the deaths of 2,500 people over the next 25 years.

In response to the urgent need to reverse Mexico’s decreasing vaccination coverage, the Ministry of Health has launched a National Vaccination Week, the country’s first nationwide immunization campaign since the Covid-19 pandemic. From April 26 to May 3, the plan is to boost vaccine levels in the group most vulnerable to measles: children from 1 to 9 years of age. The ministry hopes to inoculate 1.8 million children to bring them up-to-date with their shots, by offering vaccines free of charge at hospitals, clinics, schools, and health centers.

Measles isn’t the only disease being targeted in Mexico: Children over 4 years old are also being offered the DPT (diphtheria, pertussis, and tetanus) vaccine, and a pneumococcal booster is being offered at 12 months of age. Adolescents, adults over 60, and pregnant women are also being invited to get specific vaccines that they might need as well.

Measles is a viral disease, and it is considered to be one of the most contagious in the world. It mostly spreads among children. It is transmitted by contact with infected nasal or pharyngeal secretions and through the air, and it initially affects the respiratory tract. Symptoms include a high fever, cough, abundant nasal discharges, and a skin rash that spreads all over the body. Complications can include blindness, encephalitis (inflammation of the brain), diarrhea, dehydration, ear infections, and pneumonia. In severe cases, it can be fatal.

This story originally appeared on WIRED en Español and has been translated from Spanish.