The visiting friends or relatives traveler in the 21st century: time for a new definition.

BACKGROUND: Travelers visiting friends or relatives (VFR travelers) are a group identified with an increased risk of travel-related illness. Changes in global mobility, travel patterns, and inter-regional travel led to reappraisal of the classic definition of the term VFR. METHODS: The peer-reviewed literature was accessed through electronic searchable sites (PubMed/Medline, ProMED, GeoSentinel, TropNetEurop, Eurosurveillance) using standard search strategies for the literature related to visiting friends/relatives, determinants of health, and travel. We reviewed the historic and current use of the definition of VFR traveler in the context of changes in population dynamics and mobility. RESULTS: The term "VFR" is used in different ways in the literature making it difficult to assess and compare clinical and research findings. The classic definition of VFR is no longer adequate in light of an increasingly dynamic and mobile world population. CONCLUSIONS: We propose broadening the definition of VFR travelers to include those whose primary purpose of travel is to visit friends or relatives and for whom there is a gradient of epidemiologic risk between home and destination, regardless of race, ethnicity, or administrative/legal status (eg, immigrant). The evolution and application of this proposed definition and an approach to risk assessment for VFR travelers are discussed.