Among immunocompromised travelers, the risk of acquiring travel-related infections may be higher due to deficits in their immune system and their potential to have attenuated responses to vaccines.
More than 1 billion people worldwide crossed international borders in 2014. International travelers, especially those visiting tropical and subtropical locations, are at increased risk for acquiring infections that may lead to adverse health events during or upon return from travel.[2,3] Among immunocompromised travelers, the risk of acquiring travel-related infections may be higher due to deficits in their immune system and their potential to have attenuated responses to vaccines.
Furthermore, live attenuated vaccines may be contraindicated in certain immunocompromised patients. In the United States, as the prognosis of multiple cancer types has improved over the past few decades, more people living with cancer are enjoying a better quality of life, which includes increased mobility and the ability to travel. Recent studies have highlighted that international travel is common among patients living with cancer, both during therapy and soon after therapy has concluded, even among highly immunocompromised hematopoietic stem cell transplant recipients.[6,7] Pre-travel health counseling and interventions should be optimized in these patients, and clinicians should consider referral to a travel medicine specialist for the provision of specific counseling and interventions.
A 52-year-old woman with a history of invasive ductal breast cancer, who underwent a mastectomy followed by chemotherapy 2 years prior and is currently on an aromatase inhibitor, is referred by her oncologist for a pre-travel consultation 2 months ahead of a trip to Ghana. She is traveling with her church group and will be staying in a hotel, although she will be visiting homes of local church members. Her only other international travel has been to Jamaica and Mexico; at the latter destination she experienced diarrhea. She does not recall receiving any recent vaccinations other than an annual flu shot.
Preventive strategies in the form of proper planning, counseling, and vaccine and chemoprophylaxis interventions are helpful in ensuring a safe and healthy trip for cancer patients when they travel to international destinations (Table 1). In order to properly prioritize and customize pre-travel interventions, a structured risk assessment should be conducted based on the travel itinerary and nature of activities planned, as well as stratification of the patient according to degree of immunocompromise. Consultation should occur at least 4 to 6 weeks in advance of travel, although in certain cases, particularly when booster doses of vaccines are required for maximal protection, even more advanced planning is preferable.
Many websites offer comprehensive, up-to-date information on recommendations and requirements prior to embarkation. Both the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) offer general and country-specific information about epidemiologic risks and related recommendations for vaccination and chemoprophylaxis.[8,9]
Patients should keep medications and supplies in their original packaging and pack them in their carry-on bags. A clinician letter detailing the medical condition(s) and prescribed medication(s), including generic names, should be provided. Patients should be advised on personal safety and the differences between trip, travel medical, and medical evacuation insurance. In addition, patients should pack a travel health kit that includes additional over-the-counter medications and/or supplies that might be helpful in the setting of minor illness or injury, such as analgesics, antihistamines for allergy, and a first aid kit.
Patients with malignancy who are on active treatment are at increased risk for deep vein thrombosis, and long-haul travel greater than 6 hours is also associated with increased risk. Patients should be counseled on staying well hydrated, wearing loose-fitting clothing, and stretching while awake. For patients who are at particularly high risk, compression stockings can be prescribed.
In general, vaccines that should be considered prior to travel include: 1) routine vaccinations that would benefit the patient regardless of travel, particularly since certain routine vaccine-preventable illnesses like polio and measles are re-emerging in localized outbreaks[13,14]; 2) travel-related vaccinations, based on specific epidemiologic risks that may be encountered; and 3) vaccines that might be required prior to entry to certain countries. Table 2 contains a list of common vaccines given prior to international travel.
The risks associated with receipt of live attenuated vaccines must be carefully weighed against potential benefit, and are not advised in patients with severe immunologic compromise (Table 3). It is very important that the effects of the increasingly diverse group of immunologics and biologics used in cancer therapy be well understood by the vaccine provider, since the spectrum and duration of immunosuppressive effects can vary widely. Since yellow fever is a live attenuated vaccine, the potential harms and benefits of vaccination in relation to underlying immune status must be carefully considered. For patients who cannot safely receive vaccination that is required for disembarkation but who will be visiting a location where little epidemiologic risk occurs, a waiver letter can be written by a certified yellow fever vaccine provider. For patients who are planning a trip that may result in natural exposure to disease, attendant risks and possibility of altering an itinerary to avoid natural exposure should be discussed.
Data regarding efficacy of travel vaccines in individuals who are immunosuppressed because of cancer or related therapy are limited. Certain severely immunosuppressed patients (ie, those with recent receipt of monoclonal anti-CD20 antibodies) may be unlikely to respond to vaccinations, in which case alternate additional strategies, such as immune globulin for hepatitis A prevention, should be considered.
Mosquitoes, ticks, and other arthropod vectors can transmit a number of infections. Vaccination or chemoprophylaxis strategies can protect travelers against several of these diseases, such as malaria, yellow fever, and Japanese encephalitis, among others. However, not all vector-borne infectious agents have vaccine or chemoprophylaxis options to reduce the incidence of disease acquisition (dengue virus, chikungunya virus, zika virus, among others); therefore, bite prevention strategies, such as the use of effective topical repellents, as well as permethrin-embedded clothing or bed netting in the appropriate setting, should be considered. I recommend that travelers utilize insect repellent that contains at least 25% DEET. Sunscreen, when applied concurrently with insect repellent, should be applied first.
Patients traveling to areas with malaria should obtain prophylactic medications prior to travel. The CDC maintains a comprehensive, up-to-date list of countries with malaria, and country-specific recommendations are well outlined. Chloroquine remains the drug of choice for areas of the world where there is still chloroquine-sensitive malaria. For most areas with chloroquine-resistant malaria, atovaquone/proguanil, mefloquine, and doxycycline all have similar efficacy for malaria prevention; drug-drug interactions must be reviewed.
Patients traveling to areas where food hygiene and water safety are concerns should be counseled to avoid tap water (including ice), as well as to generally avoid raw vegetables and unpasteurized dairy products. Cooked, steamed, or boiled food, and fruit that can be self-peeled, is generally considered to be safe.
Traveler’s diarrhea is usually a self-limited illness caused by viruses or noninvasive strains of Escherichia coli. Although much less common, enteroinvasive bacteria or parasites may be causative agents. Over-the-counter loperamide can be used for mild diarrhea without bloody stools or persistent fever (> 24 hours) and/or abdominal cramps. For more severe diarrhea, patients can be prescribed an antibiotic for initiation of self-treatment in the appropriate setting, and this may be particularly important for immunocompromised patients who may experience more severe symptoms or a longer duration of symptoms. Fluoroquinolones or macrolides are the most commonly prescribed antimicrobials, and the choice of which to use is dependent on destination-specific antimicrobial resistance patterns.
Counseling, vaccination, and chemoprophylaxis strategies can help patients who are traveling during or after cancer treatment. My patient was counseled on optimal preparations prior to her trip to Africa. She received yellow fever, typhoid, hepatitis A, and tetanus-diphtheria-pertussis vaccinations prior to departure, and was given a certification stamp for yellow fever vaccination, as was required for entry to Ghana. She also received atovaquone/proguanil for malaria prophylaxis. She returned uneventfully and has plans to return next year.
Financial Disclosure: The author has no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.
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