Many Americans Traveling Overseas at Risk for Measles, Hepatitis A

SAN DIEGO – Many people who travel internationally are not fully vaccinated before their trip, leaving them at risk for contracting contagious diseases such as measles and hepatitis A, suggest two studies being presented at IDWeek 2015. 

The findings suggest the lack of pretravel vaccination was a factor in some recent illness outbreaks. More than half of eligible Americans visiting a travel clinic prior to international travel did not receive the measles, mumps and rubella (MMR) vaccine as recommended, despite being at risk for measles, according to one study. 

Another study reports on a 2015 hepatitis A outbreak at a popular resort destination in Mexico that could have been avoided with proper vaccinations. Researchers in this study noted that exposure to contaminated food and water while travelling internationally is the most common way Americans become ill with this virus. 

Measles Vaccination Study 

A study of more than 40,000 U.S. travelers found that 16% were eligible for the MMR vaccine – meaning they were not immunized or under-immunized and were medically eligible – but fewer than half of them received the vaccine during pre-travel consultation, despite CDC guidelines. 

The research focused on 40,810 adults born after 1956 who received pre-travel consultations between 2009 and 2014 at 24 sites associated with Global TravEpiNet (GTEN), a -CDC-supported consortium of clinical sites that provide pre-travel health care. Of those adults, 6,612 were eligible for vaccination, but only 3,135 received the MMR vaccination before travel.

“Measles is one of the most contagious diseases in the world and even brief exposure can lead to infection,” Emily Hyle, MD, lead author of the measles vaccination study and Instructor at Harvard Medical School and Massachusetts General Hospital, Boston said during a media event about the study. “Many travelers heading to developed countries, including those in Europe, might not realize that there are outbreaks of measles occurring in those areas, and they are at risk for becoming ill.” 

Hepatitis A Vaccination Study 

In another study, researchers reported on an outbreak of hepatitis A infection in Tulum, Mexico. 

They reported on 29 cases of acute hepatitis A that occurred in Americans who traveled to Tulum between Jan. 5 and March 20, 2015. Of the patients, 17  stayed at one of nine resorts within a few miles of each other, 23  eported eating seafood and 16 said they ate ceviche, raw seafood cured in lime juice. None had received the hepatitis A vaccination prior to travel. 

“Hepatitis A vaccination prior to travel is the most effective way to avoid infection, regardless of length of stay or quality of lodging,” Monique Foster, MD, MPH, lead author of the hepatitis A study, and Epidemic Intelligence Service Officer in the Division of Viral Hepatitis at CDC in Atlanta said in a press release about the study. 


1. Hyle E, Rao S, Jentes E, et al. Abstract 113: Pre-travel assessment of measles immunity status and administration of MMR for adult international travelers seen in Global TravEpiNet sites
2.   Foster M, Collier M, Spruit-McGoff K, et al. Abstract 1049: Hepatitis A virus infection among travelers –– Tulum, Mexico, 2015. Both presented at: IDWeek 2015. Oct. 7-11, 2015. San Diego.