Resident Editors: Matthew Spinelli, MD and Emma Bainbridge, MD

Faculty Editor: Miranda Dunlop, MD

Bottom Line

• Use the CDC website (www.cdc.gov/travel) for the most detailed and current information on your patient’s destination
• Consider appropriate prophylaxis and immunizations, ideally 4-6 weeks before travel           

Background

• Individuals traveling to international destinations are at increased risk for diseases not commonly encountered in the United States.
• The CDC website at www.cdc.gov/travel provides helpful health information for international travelers as well as country-specific recommendations for immunizations.
• Safety first! Travelers are 10X more likely to die as a result of injury than from an infectious disease. Motor vehicle accidents account for the largest number of these injuries in U.S. tourists (32%), followed by homicide (18%) and drowning (14%).
• High risk groups: Immigrants from less developed countries returning home to visit friends and relatives (VFR) often do not appreciate changing risks and waning immunity. They have the highest incidence of many travel-related infectious diseases, such as malaria, typhoid fever, tuberculosis, hepatitis A, and sexually transmitted diseases.

Pre-travel evaluation

• International travelers should be evaluated at least 4-6 weeks before their scheduled trip, especially if traveling to tropical areas.
• Relevant medical history, including pre-existing illnesses, current immunosuppression or pregnancy, and prior vaccinations, should be obtained.
• Details of a patient’s travel itinerary, including countries to be visited, duration, urban vs. rural location, types of accomodation (e.g. homestay vs hotel), modes of transportation, and planned activities should be discussed to assess specific risks.
• General medical advice:
  • Bring adequate supplies of prescription meds for chronic medical problems as well as a list of prescribed meds and doses.
  • Recommend travel insurance for emergency medical care abroad.
  • Local U.S. consulates can assist in locating medical facilities and provide information about medical evacuation for seriously ill patients.
• Food and water consumption: food and water-borne illnesses, especially diarrheal diseases, are common.
  • Consume bottled water and canned soft drinks. Avoid ice unless it is known to be made from safe water.
  • Observe the rule of P’s: only consume food that is Peeled, Packaged, Purified, or Piping hot.
• Insect exposure: Wear protective clothing and use insect repellents and bed nets to prevent insect-borne diseases. For skin, use products containing DEET (between 10-50%); for clothing and fabrics, permethrin-containing products provide protection even after repeated laundering.
• Sexually transmitted diseases: Bring condoms and advise caution in areas where HIV and other STIs are highly prevalent.

Disease prevention

• International travelers often require additional vaccines and prophylactic medications against diseases commonly encountered in endemic areas.
• Travelers should ensure they are up to date on their routine vaccines (refer to Adult Immunization chapter).

Table: Commonly recommended vaccinations for travel (vary by country; not a comprehensive list)         

Malaria prophylaxis

• Malaria, caused by Plasmodium falciparum, P. vivax, P. ovale, or P. malariae infection, affected over 200 million people and accounted for nearly half a million deaths in 2015. Immigrants returning home (VFRs) and pregnant women are at particularly high risk.
• Suspected or confirmed malaria constitutes a medical emergency because of the risk of severe or life-threatening manifestations, including seizures, coma and death. Travelers should be counseled to seek medical care for symptoms of malaria, including fevers, flu-like illness, and jaundice.
• Travelers to endemic areas are at increased risk for infection and should take preventive measures including use of mosquito nets, screens, and insect repellents. Chemoprophylaxis is also strongly recommended, and medication choice will depend on the epidemiology of the region being visited, duration of travel, cost, and possible adverse effects.

Table: Malaria chemoprophylaxis

Traveler’s diarrhea

• The most common health risk for travelers to developing countries. High risk (>30%) regions include Africa (except South Africa), Asia (except Singapore and Japan), Middle East, Mexico, South and Central America. Bacterial pathogens account for 80-90% of cases; Enterotoxigenic E. coli is the most common causative agent. Symptoms may vary in severity and include fever, abdominal pain/cramping, nausea, vomiting, and diarrhea, sometimes with blood.
• Most cases of traveler’s diarrhea are self-limited and resolve within 2-7 days, however antibiotic therapy may be considered if symptoms are more severe (i.e. fever, dysentery) or persistent. Antibiotics only reduce symptom duration by one day on average, and are not routinely recommended due to increased resistance, especially to fluoroquinolones.
  • If antibiotics are prescribed, azithromycin 1g x1 dose is first line, especially for travelers to Southeast Asia, where fluoroquinolone resistance in increasing. Azithromycin is safe in pregnancy.
  • Fluoroquinolones are second line (e.g. ciprofloxacin 500mg BID x 3 days) For all cases, hydration should be encouraged, and oral rehydration therapy packets (available in pharmacies throughout the world) should be used for moderate to severe cases.
  • If diarrhea persists despite therapy, travelers should be evaluated by a doctor and treated for possible parasitic infection.

Acute Altitude Illnesses

• A spectrum of syndromes that occur when travelers have insufficient time to acclimatize to altitudes over 9000 feet. The rate of ascent is as important as the absolute altitude. Definitive treatment is descent to lower altitudes.
  • Acute Mountain Sickness: Headache + at least one other symptom (nausea/vomiting, anorexia, fatigue, dizziness, and/or insomnia); Onset: 2-12 hours after ascent; symptoms usually resolve within 1-3 days. For mild cases, treatment is rest and hydration. Acetazolamide can speed recovery. Dexamethsone and supplemental oxygen can also alleviate symptoms.. Descent is effective treatment but not necessary.
  • High Altitude Cerebral Edema: Marked by altered mental status, including lethargy, confusion and ataxia. Coma and death may occur as soon as 24 hours after the onset of symptoms. Immediate descent, supplemental oxygen and dexamethasone are imperative, and acetazolamide may be beneficial as well.
  • High Altitude Pulmonary Edema: Marked by breathlessness and decreased exercise tolerance, followed by dry cough with progression to bloody sputum. May be rapidly fatal. Descent to lower altitudes is imperative. Supplemental oxygen is also indicated. Nifedipine can be used for both prophylaxis and treatment. Tadalafil and sildenafil are effective as prophylaxis.
  • Prevention: promote acclimatization:
    • Ascend gradually--ideally, from low altitude to no more than 9000 feet altitude in the first day and subsequently < 1600 feet per day
    • Avoid alcohol and strenuous exercise for the first 48 hours
    • May pretreat with acetazolamide 125 mg BID beginning one day before ascent and continuing at least 2 days after reaching highest altitude, but warn about peripheral paresthesias. Dexamethasone is an alternative and/or rescue medication that can be administered on the day of ascent in those who do not tolerate acetazolamide, but should not be discontinued abruptly at altitude as it may precipitate symptoms.

Post-travel management

• Travelers should be advised to seek immediate medical care upon return if they develop any illnesses. Fever and diarrhea are the most common complaints.
• Patients with a fever should be evaluated for malaria and other febrile illnesses to which they were potentially exposed during their travel.
  • Malaria is the most common cause of fever in a returning traveler, particularly for VFRs who are at twice the risk.
  • Dengue is the most common specific etiologic agent for travelers returning from South East Asia and is one of the top three infections for travelers to all other regions except sub-Saharan Africa and Central America.
  • Rickettsial infection should be considered in travelers returning from sub-Saharan Africa as it is the second most common etiologic agent after malaria.
• Patients with persistent diarrhea should have stool culture and O&P sent to evaluate for giardiasis and other parasitic diarrheal diseases.

Traveler’s health resources

• San Francisco DPH Adult Immunization and Travel Clinic: www.sfcdcp.org/aitc.html (415) 554-2625
• CDC Traveler’s Health Information: www.cdc.gov/travel
• International Society of Travel Medicine: www.istm.org
• US Embassies and Consulates: www.usembassy.gov

References

Centers for Disease Control and Prevention. The Yellow Book. CDC Health Information for International Travel 2018. https://wwwnc.cdc.gov/travel/page/yellowbook-home. Accessed 03/28/2018.

Imray C, Booth A, Wright A, Bradwell A. Acute altitude illnesses. BMJ (Clinical Research Ed.) 2011, 343, d4943.

Luks A, McIntosh S, Grissom CK, et al. Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness. Wilderness Environ Med. 2010 Jun;21(2) 146-55.

Kamata K, Birrer RB, Tokuda Y. Travel medicine: Part 1-The basics. J Gen Fam Med. 2017 Apr 4;18(2):52-55.

Schwartz BS, Larocque RC, Ryan ET. In the clinic. Travel Medicine. Annals of Internal Medicine. 2012 June 5; 156(11).

Wilson ME, Weld LH, Boggild A, et al. Fever in returned travelers: results from the GeoSentinel Surveillance Network. Clin Infect Dis 2007; 1560 (44).

World Health Organization . Meeting of the Strategic Advisory Group of Experts on immunization, April 2013 - conclusions and recommendations. Wkly Epidemiol Rec 2013; 201(88).