Travel medicine has come a long way in recent years, and The ClinicalAdvisor brings you up to date on what you need to know.
Traveling abroad can inject adventure into patients’ lives, but a trip complicated by sudden illness will not leave happy memories. Travelers who neglect preventive health care and opt for the hope-for-the-best approach could well be setting themselves up for serious, long-lasting illness.
During checkups, all patients should be questioned about any plans for travel outside the United States and advised to seek medical attention at least six weeks before departure. Since they often underestimate their risk, immigrants who visit family members abroad are among the most likely to return to the United States with an infection, according to a recent study (page 50). While many know to plan ahead medically, others do not, leaving it up to you to identify future travelers and assist with their pre-trip needs.
Assessing travel risk
The level of risk and types of exposures incurred by travel relate to several factors other than the destination. These include the level of hygiene and sanitation of the accommodations, duration of travel and season, activities planned, and the underlying health of the individual. For example, venturing to remote areas for emergency relief efforts where potable water and supplies are limited poses a much higher level of risk compared with a pleasure trip to a European city.
Ideally, individuals anticipating travel to a foreign country should visit a health-care provider at least four to eight weeks prior to departure. But patients should be informed that while some services may be suboptimal if they notify you later than this, it is never too late to seek preventive care. Even if departure is imminent, patients should be seen since some vaccine schedules may be compressed and other provisions made.
The pre-trip medical visit is also a time to urge patients to create a travelers’ version of the CDC’s first-aid kit in its well-regarded “Yellow Book” for international travel (Table 1). Items will vary according to the individual patient, destination, and planned activities. Remember that a health kit should be accessible at all times (e.g., in carry-on baggage when allowable) and on excursions. Those who choose to purchase rather than assemble their own kit should take the time to go through its contents and add items as necessary. Some manufacturers of pre-assembled travel kits include Adventure Medical Kits, Chinook Medical Gear, Harris International Health Care, Travel Medicine, Inc., and Wilderness Medicine Outfitters.
A pre-departure office visit also offers an opportunity to recommend that patients review their health insurance. Most U.S. health-insurance policies skimp on international coverage, so travelers may wish to purchase short-term travel insurance, paying special attention to the fine print if there is a pre-existing condition or if patients are participating in high-risk recreational activities in which medical evacuation might become necessary. A list of U.S.- and foreign-based MedEvac and travel insurance companies is available from the State Department.
Diarrhea prevention and first-aid
One of the most common infections acquired while overseas is traveler’s diarrhea, which can be caused by bacteria (Escherichia coli, salmonella, shigella), viruses (rotavirus, hepatitis A, norovirus), or a parasite (Giardia, Cryptosporidium). Risk for enteric infection can be reduced by selecting food and water with care and using caution when swimming or wading in pools or natural water sources. (For further details, see the CDC Food and Water Safety page at: www.cdc.gov/travel/contentSafeFoodWater.aspx. Accessed September 10, 2007.)
Most diarrhea episodes are self-limited, but patients should still be advised to stay hydrated and use oral rehydration solutions as needed if diarrhea persists longer than 24 hours.
The World Health Organization (WHO) recommends medical attention be sought for diarrhea that persists beyond three days or is associated with bloody stools, vomiting, or fever. Ciprofloxacin or levofloxacin (or azithromycin as an alternative for adults and as first-line therapy for children) should be available for empiric use if health care will be out of reach. Antimotility agents may provide some relief in adults but aren’t safe for children. WHO recommendations regarding prevention and management are available at http://whqlibdoc.who.int/publications/2007/9789241580397 (accessed September 10, 2007).
While vaccination is the key preventive strategy in travel medicine, no vaccine is meant to supplant good hygienic practices. Pre-travel vaccination falls into one of three categories:
1. Catch-up on routine immunizations: These should be complete, including measles, mumps, and rubella (MMR), diphtheria, tetanus, pertussis, poliomyelitis, meningococcal, pneumococcal, hepatitis B, Hemophilus influenzae type b, human papillomavirus, rotavirus, varicella, and influenza vaccines as indicated. (See the CDC adult immunization schedule available at: http://www.cdc.gov/vaccines/schedules/index.html. Accessed September 10, 2007.)
Most adults and children in the United States have been adequately immunized against measles and mumps, but those who have slipped through the cracks or who have yet to receive their second MMR dose will be at increased risk when traveling. Measles infects more than 20 million and kills more than 300,000 individuals each year worldwide.
Susceptible travelers are at risk in nearly every region of the world. Recent mumps outbreaks have been reported in Great Britain and Canada. Adults and children older than 12 months should have received two doses of MMR vaccine separated by at least 28 days as part of routine immunizations. If they haven’t or their status is unknown, immunization with two doses should commence prior to departure if possible. If children aged 6-11 months are to travel, an exception to the minimum age for MMR may be made to provide optimal protection while abroad.
Diphtheria and tetanus toxoid boosters are indicated every 10 years for U.S. adults, and acellular pertussis vaccine may be added according to risk. Travelers to any area (especially those with low immunization rates) may be exposed to these potentially fatal diseases. To find out if your patients are fully protected and current, see the CDC child and adult immunization schedule (available at: www.cdc.gov/vaccines/recs/schedules/default.htm. Accessed September 10, 2007).
2. Travel-specific vaccinations: Vaccines are available for several diseases that are prevalent only outside the United States and therefore not a part of routine immunizations here (e.g., hepatitis A, Japanese encephalitis, and typhoid fever). Some “routine” vaccines (e.g., meningococcal and hepatitis A) for special populations (i.e., infants, the elderly, and the immunocompromised) may be advised for all people visiting endemic areas.
For those traveling to regions endemic for yellow fever, mandatory vaccination with one dose of vaccine by a WHO-certified provider is required. The certificate of vaccination is valid starting 10 days after injection and lasts for 10 years.
Periodic epidemics of hepatitis A in the United States have been curtailed because of the addition of the hepatitis A vaccine to routine immunizations, but it remains one of the most commonly acquired travel-related infections. If not previously immunized, travelers to moderate- to high-risk areas should receive a series of two vaccines six months apart prior to departure. However, if there is only time for the first dose, patients are usually very well protected in the short term.
Those traveling to regions in which Japanese encephalitis is endemic may require pre-departure vaccination, especially if staying for an extended period or visiting rural or farm areas. This three-shot series should be spread out over one month, but it can be condensed to two weeks if time is short.Travelers at high risk of typhoid exposure should receive the typhoid vaccine, which is given as a single dose one week prior to departure and may be available in combination with hepatitis A vaccine.
Antibiotics including antimalarials may interfere with typhoid vaccine efficacy and should be halted temporarily.
3. Boosters: Among those who are susceptible because of underlying medical problems and/or travel to high-risk areas, boosters may be required to sustain protection against vaccine-preventable diseases (e.g., Japanese encephalitis, meningitis, pneumonia, polio, tetanus, diphtheria, pertussis, typhoid fever, and yellow fever). Recommended booster frequency varies by vaccine type.
Polio still a concern
Most clinicians have never seen a case of paralytic polio. Efforts organized by the Global Polio Eradication Initiative (spearheaded by WHO, Rotary International, the CDC, and UNICEF) have reduced worldwide prevalence by 99%, but polio remains endemic in India, Afghanistan, Pakistan, and Nigeria.
Travelers to these and other countries in Africa, South and Southeast Asia, and the Middle East are advised to receive a single lifetime booster of inactivated polio vaccine (assuming completion of their primary series as a child or an adult). If polio immunization status is unknown or incomplete, patients should receive a complete series of polio vaccination beginning as early as possible before departure. Check CDC outbreaknotices (wwwn.cdc.gov/travel/contentPolioOutbreaks.aspx. Accessed September 10, 2007), as epidemics sometimes emerge in countries that were previously polio-free.
Travelers to malaria-endemic regions need information related to the symptoms of the disease and how to prevent mosquito bites. Malaria is characterized by fever within seven days of first possible exposure and three months of the last possible exposure. Accompanying symptoms are not always present in milder cases but include chills, body aches and headaches, weakness, abdominal pain, diarrhea and vomiting, and cough.
Chemoprophylaxis is an important component of malaria prevention. Most U.S. travelers who contract malaria fail to comply with region-specific prophylaxis guidelines. According to the species of Plasmodium and resistance patterns in the region, malaria prophylaxis ranges from bite prevention only (type I) to bite protection plus chemoprophylaxis with either chloroquine (type II), chloroquine plus proguanil (type III), or mefloquine, doxycycline or atovaquone-proguanil (type IV). Further details on malaria prevention are available from WHO (http://whqlibdoc.who.int/publications/2007/9789241580397. Accessed September 10, 2007).
Avian flu: An emerging concern
Avian influenza A (H5N1) has been confirmed in 321 human cases and has resulted in 194 deaths worldwide to date. Human illness has largely been confined to Indonesia, Vietnam, Egypt, Thailand, China, and Turkey. Some cases in more popular travel destinations in Europe and Japan have been confined to animal populations and have not been linked to human infection. Human cases have been related primarily to exposure to an infected bird. No cases have been related to eating well-cooked poultry, and person-to-person spread has been rare.
As precautionary steps, travelers should avoid consumption of undercooked poultry, trips to bird farms or markets, and all contact with live or dead poultry. Hand-washing is an important universal preventive practice, and antibacterial hand-sanitizer gel (with at least 60% alcohol) can be used when necessary. No vaccine against H5N1 is available, but seasonal vaccination against influenza is advised for travelers.
A final word
Early planning with general and specific preventive measures will help ensure that patients derive the most satisfaction and the least worry and hardship from their travel. When questions arise, refer patients to a travel-medicine specialist or consult the resources listed in Table 2.