Study finds high-risk travelers account for nearly 1 in 5 persons seeking pre-travel advice

(Boston) -- Researchers from Boston University Schools of Medicine (BUSM) and Public Health (BUSPH) and Boston Medical Center (BMC) have found that high-risk travelers account for nearly 20 percent of patients using the five clinics of the Boston Area Travel Medicine Network (BATMN). The study, which appears online in Mayo Clinic Proceedings, also found that these travelers often visited destinations with malaria and typhoid risk.

In 2010, an estimated 935 million travelers crossed international borders, including 28.5 million from the U.S. Certain travelers are at greater risk of disease because of age or underlying medical conditions. Information on numbers and characteristics of persons going overseas has not been as readily available as reports of disease in returning travelers. This study is one of the first to provide information on high-risk persons where travel and demographic characteristics are stratified by traveler health status.

In this study, high-risk travelers were categorized into one of three groups, immunocompromised travelers, persons with non-immunocompromising medical comorbidities (cardiac or pulmonary disease) and pregnant women. Of 15,440 travelers, 74.3 percent had medical comorbidities, 23.3 percent were immunocompromised travelers,17.9 percent were high-risk and 2.5 percent were pregnant. High-risk travelers were older than healthy travelers and included a greater proportion of persons older than 60 years. Overall, 93.9 percent of high-risk travelers visited countries with medium or high risk of typhoid fever, 85.7 percent visited malaria-risk countries, and 22.8 percent visited yellow fever-endemic countries. Among travelers to yellow fever-endemic countries, 44.4 percent of immunocompromised travelers and 34.8 percent of pregnant women received yellow fever vaccine. Among eligible high-risk travelers, 35.7 percent received either tetanus-diphtheria or tetanus-diphtheria-pertussis vaccinations, 33.3 percent received influenza vaccination and 14.5 percent received a pneumococcal vaccination.

"We found that many travelers seeking pre-travel care are high-risk and that they have a unique set of needs in terms of travel risks, vaccinations and counseling," said lead author Natasha Hochberg, MD, MPH, assistant professor of Medicine at BUSM, assistant professor of epidemiology at BUSPH and co-director of BMC's Travel Clinic. "We recommend that travelers, particularly high-risk travelers, seek care early in the course of their travel planning to allow adequate time to review their needs and that they be referred to experienced travel medicine providers," she added.

For example, most travelers to yellow fever-endemic countries received the yellow fever vaccine. However, the decision to provide live virus yellow fever vaccines to high-risk persons requires a complicated, informed decision-making process to review risks and benefits. "Travel clinic visits need adequate time to address the additional elements of the medical history as well as to allow counseling topics to be covered thoroughly. This information is meant to raise awareness of the benefit of pre-travel care for high-risk travelers and improve understanding among clinicians regarding their patients' needs and the provision of appropriate advice," added Hochberg.

This study was funded by a cooperative agreement between the CDC and Boston Medical Center (U19C100508-01).

Co-authors Elizabeth D. Barnett, MD, has received research funding from Intercell, Cerexa, and Sanofi Pasteur, and royalties from Elsevier. Lin H. Chen, MD, has received honoraria from Thompson Media LLC and Shoreland Inc, and research funding from Xcellerex Inc.