Christine M. Benoit

International travel by persons with medical comorbidities: understanding risks and providing advice.

OBJECTIVE To describe the medical conditions, travel plans, counseling, and medications prescribed for high-risk international travelers. PATIENTS AND METHODS This cross-sectional study was conducted from March 1, 2008, through July 31, 2010, in 5 clinics in the greater Boston area. We assessed all travelers seen for pretravel care and compared demographic characteristics, travel plans, pretravel counseling, and interventions for healthy and high-risk travelers (as defined by medical history or pregnancy). RESULTS Of 15,440 travelers, 2769 (17.9%) were high-risk; 644 of 2769 (23.3%) were immunocompromised travelers, 2056 (74.3%) had medical comorbidities, and 69 (2.5%) were pregnant women. The median age of high-risk travelers was 47 years compared with 32 years for healthy travelers (P=.0001). High-risk travelers visited the clinic a median of 25 days (range, 10-44 days) before departure. Overall, 2562 (93.9%) of high-risk travelers visited countries with medium or high risk of typhoid fever, 2340 (85.7%) visited malaria-risk countries, and 624 (22.8%) visited yellow fever-endemic countries. Of travelers to yellow fever-endemic countries, 8 of 23 (34.8%) pregnant women and 64 of 144 (44.4%) immunocompromised travelers received yellow fever vaccine. Of eligible high-risk travelers, 11 of 76 (14.5%) received a pneumococcal vaccine, 213 of 640 (33.3%) influenza vaccine, and 956 of 2681 (35.7%) either tetanus-diphtheria or tetanus-diphtheria-pertussis vaccine. CONCLUSION High-risk travelers made up nearly 20% of patients in these travel clinics, and they mostly traveled to destinations with malaria and typhoid risk. For health care professionals caring for travelers with underlying medical problems, providing appropriate travel counseling and making vaccine decisions, such as for yellow fever, are complex. Travelers with complicated medical histories may warrant evaluation by an experienced travel medicine specialist.

Knowledge, attitudes, and practices of US practitioners who provide pre-travel advice.

BACKGROUND As international travel increases, many health care professionals are being asked to provide pre-travel advice. We designed an anonymous web-based survey to assess the extent to which primary care providers (PCPs) provide travel medicine advice and how their understanding and delivery of itinerary-specific advice and management compare with that of travel medicine specialists. METHODS We surveyed randomly selected US PCPs registered in the Pri-Med Institute (now pmiCME) database and US travel medicine specialists from the International Society of Travel Medicine (ISTM), American Society of Tropical Medicine and Hygiene (ASTMH), and Centers for Disease Control and Prevention (CDC) yellow fever (YF) vaccine provider mailing lists. SAS software (SAS Institute, Cary, NC, USA) was used for all analyses. RESULTS Of 14,932 e-mails sent to valid e-mail addresses, 902 yielded complete or partially completed surveys (6.0% response rate). Eighty percent of respondents personally provided pre-travel advice (95% of travel medicine specialists versus 73% of PCPs). About two thirds of PCPs (68%) providing pre-travel consultations saw <50 travelers per year whereas 30% of travel medicine specialists saw <50 travelers per year. More travel medicine specialists (59%) than PCPs (18%) saw >500 travelers per year. Familiarity with travel-specific vaccines (YF, Japanese encephalitis) and provision of written educational materials increased as volume of travelers increased. Familiarity with antimalarial side effects and malaria resistance patterns, and knowledge scores based on brief pre-travel scenarios were higher in travel medicine specialists, ASTMH or ISTM certificate holders, and respondents who saw more pre-travel patients. CONCLUSIONS Many PCP survey participants provided pre-travel advice, but most saw few travelers. Volume of travelers and holding an ASTMH or ISTM certificate had the greatest influence on knowledge of travel medicine and provision of appropriate advice and recommendations. Creating easily accessible travel medicine education programs for US providers from a wide range of disciplines is needed to improve the management of travelers.

Prevalence of Dengue Virus Infection in US Travelers Who Have Lived in or Traveled to Dengue-Endemic Countries

BACKGROUND Dengue virus (DENV) infections may occur in travelers. OBJECTIVES To determine prevalence of anti-DENV IgG antibody in travelers who lived in or visited dengue-endemic countries and to describe risk factors and characteristics associated with infection and subsequent anti-DENV IgG antibody presence. METHODS Participants were enrolled from travel clinics of the Boston Area Travel Medicine Network from August 2008 through June 2009. Demographic information, trip duration, travel history, and a blood sample were collected. Serum samples were tested for anti-DENV IgG antibody by indirect IgG enzyme-linked immunosorbent assay (ELISA), and antibody-mediated virus neutralization by plaque reduction neutralization test (PRNT) for anti-DENV IgG antibody-positive and selected negative samples. Participants were stratified into group 1: born in dengue-endemic countries; group 2: born in nonendemic countries but lived continuously for ≥1 year in a dengue-endemic country; group 3: born in nonendemic countries and traveled to a dengue-endemic country for ≥2 weeks but <1 year. RESULTS Six hundred travelers were enrolled. Anti-DENV IgG antibody was identified in 113 (19%) when tested by ELISA (51% in group 1, 40% in group 2, and 6.9% in group 3) and in 71 (12%) by PRNT (42% primary monotypic and 58% heterotypic reactive responses). Sensitivity and specificity of the ELISA based on PRNT results were 85% to 100% and 79% to 94%, assuming up to 15% misclassification of ELISA negative results. Presence of anti-DENV IgG antibody by ELISA was associated with years lived in dengue-endemic countries and birthplace in the Caribbean for group 1, receipt of Japanese encephalitis vaccine in group 3, and self-reported history of dengue in all three groups. CONCLUSIONS Nineteen percent of participants who were born, lived in, or traveled to dengue-endemic countries had anti-DENV IgG antibody by ELISA; 12% had antibodies by PRNT, 85% of whom had no history of dengue. Presence of DENV antibodies was associated with years lived in dengue-endemic countries and self-reported history of dengue.

Malaria Prevention Strategies: Adherence Among Boston Area Travelers Visiting Malaria-Endemic Countries.

We conducted a prospective cohort study to assess adherence to malaria chemoprophylaxis, reasons for nonadherence, and use of other personal protective measures against malaria. We included adults traveling to malaria-endemic countries who were prescribed malaria chemoprophylaxis during a pre-travel consultation at three travel clinics in the Boston area and who completed three or more surveys: pre-travel, at least one weekly during travel, and post-travel (2-4 weeks after return). Of 370 participants, 335 (91%) took malaria chemoprophylaxis at least once and reported any missed doses; 265 (79%) reported completing all doses during travel. Adherence was not affected by weekly versus daily chemoprophylaxis, travel purpose, or duration of travel. Reasons for nonadherence included forgetfulness, side effects, and not seeing mosquitoes. Main reasons for declining to take prescribed chemoprophylaxis were peer advice, low perceived risk, and not seeing mosquitoes. Of 368 travelers, 79% used insect repellent, 46% used a bed net, and 61% slept in air conditioning at least once. Because travelers may be persuaded to stop taking medication by peer pressure, not seeing mosquitoes, and adverse reactions to medications, clinicians should be prepared to address these barriers and to empower travelers with strategies to manage common side effects of antimalarial medications.

Acceptability of Hypothetical Dengue Vaccines Among Travelers

BACKGROUND Dengue viruses have spread widely in recent decades and cause tens of millions of infections mostly in tropical and subtropical areas. Vaccine candidates are being studied aggressively and may be ready for licensure soon. METHODS We surveyed patients with past or upcoming travel to dengue-endemic countries to assess rates and determinants of acceptance for four hypothetical dengue vaccines with variable efficacy and adverse event (AE) profiles. Acceptance ratios were calculated for vaccines with varied efficacy and AE risk. RESULTS Acceptance of the four hypothetical vaccines ranged from 54% for the vaccine with lower efficacy and serious AE risk to 95% for the vaccine with higher efficacy and minor AE risk. Given equal efficacy, vaccines with lower AE risk were better accepted than those with higher AE risk; given equivalent AE risk, vaccines with higher efficacy were better accepted than those with lower efficacy. History of Japanese encephalitis vaccination was associated with lower vaccine acceptance for one of the hypothetical vaccines. US-born travelers were more likely than non-US born travelers to accept a vaccine with 75% efficacy and a risk of minor AEs (p = 0.003). Compared with North American-born travelers, Asian- and African-born travelers were less likely to accept both vaccines with 75% efficacy. CONCLUSIONS Most travelers would accept a safe and efficacious dengue vaccine if one were available. Travelers valued fewer potential AEs over increased vaccine efficacy.

Pretravel Health Preparation of International Travelers: Results From the Boston Area Travel Medicine Network

Objective To inform future interventions for advising travelers. Patients and Methods We prospectively collected data on travelers seen at the Boston Area Travel Medicine Network, a Boston area research collaboration of 5 travel medicine clinics. Data from 15,440 travelers were collected from March 1, 2008, through July 31, 2010. We compared traveler and trip characteristics and differences in demographic characteristics and travel plans across the 5 clinics, including an analysis of pretravel preparations for certain high-risk destinations. Results More than half of the 15,440 travelers were female (8730 [56.5]), and 72.4% (10,528 of 14,545) were white; the median age was 34 years, and 29.4% of travelers (3077 of 10,483) were seen less than 2 weeks before their departure date. Substantial variation in racial background, purpose of travel, and destination risk existed across the 5 clinics. For example, the proportion of travelers visiting friends and relatives ranged from 7.6% (184 of 2436) to 39.0% (1029 of 2639) (18.7% [2876 of 15,360] overall), and the percentage of travelers to areas with malaria risk ranged from 23.7% (333 of 1403) to 52.0% (1306 of 2512). Although most clinics were likely to have prescribed certain vaccines for high-risk destinations (eg, yellow fever for Ghana travel), there was wide variability in influenza vaccine use for China travel. Conclusion Substantial differences in clinic populations can occur within a single metropolitan area, highlighting why individual physicians and travel clinics need to understand the specific needs of the travelers they serve in addition to general travel medicine.