Vaccination: What Travelers Need to Know

Measles and hepatitis A may pose risks to many US travelers

(RxWiki News) New evidence suggests that many Americans who travel abroad may wind up bringing home some unintended souvenirs.

Two new studies found that, despite vaccination recommendations from the Centers for Disease Control and Prevention (CDC), many Americans may not be fully vaccinated for highly contagious diseases like measles and hepatitis A before traveling internationally.

These findings suggest that lacking pre-travel vaccination in the US could potentially play a role in future illness outbreaks.

"Americans planning international travel should see their health care providers or visit a travel clinic four to six weeks before the trip to learn what vaccines are recommended before heading to their destinations," said lead measles study author Emily Hyle, MD, a professor at Harvard Medical School and Massachusetts General Hospital, in a press release. "Many travelers don't realize their risk of exposure to infections and that many can be avoided with vaccination."

Measles is a highly contagious airborne infection that spreads through coughing and sneezing. Initial symptoms can include a high fever, sore throat, hacking cough and total body rash. In severe cases, measles can lead to pneumonia, brain swelling, hospitalization and even death.

No specific treatment for measles currently exists. However, the MMR (measles, mumps and rubella) and the MMRV (measles, mumps, rubella and varicella) vaccines protect against the virus.

While measles was eliminated from the US more than 15 years ago, it still remains a significant problem worldwide — with more than 20 million cases occurring each year. US travelers who aren't vaccinated are at risk of getting sick themselves, as well as bringing the disease back home and infecting others.

For the first study, Dr. Hyle and team looked at 40,810 US adults who received pre-travel consultations between 2009 and 2014.

Of these travelers, 6,612 (16 percent) were eligible for vaccination, but only 3,135 (47 percent) received the MMR vaccination before traveling abroad.

"Measles is one of the most contagious diseases in the world and even brief exposure can lead to infection," Dr. Hyle said. "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 is a highly contagious liver infection caused by the hepatitis A virus. It is transmitted via a fecal-oral route, by way of contaminated water, food or surfaces. Signs and symptoms can include fever, nausea, exhaustion, jaundice, dark urine and stomach pain.

No specific treatment for hepatitis A currently exists. However, the hepatitis A vaccine protects against the virus. While hepatitis A infection has decreased in the US, it is more likely to occur in areas with poor sanitation and limited clean water access.

For the second study, researchers looked at 29 acute hepatitis A cases that occurred in US adults who traveled to Tulum, Mexico (a popular resort destination), between January and March of 2015. None of the patients had been vaccinated prior to travel.

Of the patients, 16 (62 percent) said they ate ceviche (a raw seafood dish), 23 (79 percent) said they ate seafood and 17 (63 percent) said they had stayed at one of nine resorts within a few miles of each other.

"Hepatitis A vaccination prior to travel is the most effective way to avoid infection, regardless of length of stay or quality of lodging," said lead study author Monique Foster, MD, MPH, an epidemic intelligence service officer at the CDC, in a press release. "Travelers to areas where hepatitis A may be a problem should avoid consuming non-bottled water, uncooked fruit and vegetables, and undercooked meats, including raw fish and shellfish such as found in ceviche."

These studies were presented Oct. 9 at the 2015 annual conference of the Infectious Diseases Society of America. Research presented at conferences may not have been peer-reviewed.

Information on funding sources and conflicts of interest was not available at publication time.

Review Date: 
October 8, 2015