Travel Medicine: Vaccines and disease prophylaxis recommendations vary by region

Issue: August 2011

In this Ask the Experts feature, John C. Christenson, MD, director of the Pediatric Travel Medicine Clinic at Indiana University, discusses the current concerns that travelers should be aware of when traveling.

What destinations/diseases are the most concerning right now?

The big issue that affects travelers going to all parts of the world is an upsurge of measles, especially in Europe. The implication this has for the US is that non-immune travelers are bringing measles back. There has been an increased number of cases in the US that will lead to a high number of cases for 2011. Certain groups in the US may have taken for granted that for many years, measles was not a serious problem. Recently, the CDC made a recommendation that anybody traveling abroad should be sure to be up-to-date in their vaccines against measles (MMR). Children as young as 6 months can receive a dose of MMR.

John C. Christenson, MD

Pertussis and hepatitis A have been conditions associated with travel abroad with the intention of adopting young children. Those travelers have to be protected against pertussis and hepatitis A, not only for themselves, but to prevent it from spreading it to other people back home.

What immunizations are recommended for all travelers, according to region?

When people come to the travel clinic, it is important to consider not only vaccines against exotic diseases, like Japanese encephalitis virus, but also routine vaccines to protect against hepatitis A, measles and pertussis should be updated if needed. This is especially pertinent in adults. Hepatitis A vaccine is by far the most frequently recommended vaccine, especially for travelers to the developing world where the quality of water and food, and sanitation may be substandard. Physicians have to do a risk assessment for other types of vaccines. The risk depends on a variety of things: history of transmission, the quality of sanitatary infrastructure, and the type of activities the traveler is planning. Here are some other recommendations, according to region:

Africa — Sub-Saharan Africa has the highest concentration of malaria transmission in the world. Those traveling to this area should receive antimalarial prophylaxis. In the same region, there are many countries with yellow fever; travelers should be vaccinated. Some countries require vaccination before entry into the country. Many countries in this region fall in the “meningitis belt”, where travelers are more susceptible to develop meningococcal infection that may cause sepsis and/or meningitis. Travelers should receive the quadrivalent meningococcal vaccine, especially during the dry season (usually December-June). In northern Africa, the risk is high for hepatitis A and typhoid fever. Several countries in southern Africa are not endemic with yellow fever and don’t require vaccination. Malaria transmission is also variable within many countries in these regions.
South America — Malaria is endemic within the Amazon, including parts of Brazil and Peru. Yellow fever is also a concern. People traveling to tropical areas need to receive yellow fever vaccine and antimalarial prophylaxis. Many countries within South America with higher altitudes are free of malaria and yellow fever. However in these areas high altitude illness can be a problem for some travelers. In some cases, a medication such as acetazolamide may be indicated to prevent the condition.
Southeast Asia — Malaria and typhoid fever are endemic in this region. Another big problem in this region is dengue fever, a mosquito-borne viral infection commonly associated with significant morbidity and frequently with mortality. There is no vaccine or medication for this condition. Bite avoidance through the use of appropriate insect repellents, clothing and bednets are highly recommended. In the rural areas of countries in this region, individuals may be at risk for Japanese encephalitis virus infection. If risk is considered to be prolonged or frequent exposures are anticipated, vaccine should be administrated. Rabies remains a serious concern for travelers to this region. Vaccination is highly recommended for those planning long stays, or who are traveling with young children at risk for dog bites.
South Pacific — In some islands of this region, malaria can be problem, so malaria prophylaxis would be appropriate. Dengue fever remains a problem in this region as well.

Most travelers to Europe, Japan, Australia and New Zealand don’t require any special vaccines. However, their vaccinations against measles should be current.

Are certain populations more susceptible to the various diseases? Are there any groups with special considerations?

Based on available studies, the group of travelers at the highest risk of acquiring a preventable disease are those who are visiting friends and relatives, which is known in travel medicine as the VFR group. They eat the local food without restrictions, and they also frequently do not take bite-avoidance precautions. Only a small percentage of these travelers visit a travel clinic before their trip to receive vaccines or education on how to prevent disease. These travelers often travel for longer periods of time and are more likely to visit rural areas where access to health care may be lacking; and risk of infection are higher. Other travelers, such as those who travel “off the beaten path,” are at higher risk for diseases. For example, the risk for infection is higher for someone who is backpacking through South America than for a traveler who is going to a more touristy type of place. We also worry about young children. Depending on what part of the world they’re going to, it might pose a high risk for them.

Has there been an increase of any infection in the US, resulting from travelers bringing it back?

Measles has been the big problem this year. Importation of mumps has been a problem in past years. We always see malaria; it’s always a prominent infection. There is minimal risk for transmission of malaria in the United States.

Aside from immunizations, what can travelers do to protect themselves from diseases that are endemic to where they are traveling?

Depending on the country and type of activity, it can be basic things like behavioral changes, like type of food they consume. When possible, they should consume foods that are well cooked. Avoiding tap water to drink or brush teeth reduces the risk of travelers’ diarrhea. In places where malaria transmission is high, travelers should wear proper clothing (long-sleeved shirts, long pants) and use insect repellent. One of the most common health issues that affect travelers is not even infectious, it’s injuries. Sprained ankles and broken bones are serious problems among travelers. Injury prevention is one of the things we try to emphasize. Young children require supervision at all times. Hotel rooms and family homes need to be child-proofed. When traveling in motor vehicles, carseats and booster seats should be used to restrain young infants and children. — by Emily Shafer

John C. Christenson, MD, is the director of the Pediatric Travel Medicine Clinic at Indiana University. Disclosure: Dr. Christenson reports no relevant financial disclosures.

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