Contacting passengers after exposure to measles on an international flight: Implications for responding to new disease threats and bioterrorism

On May 21, 2000, a passenger with measles traveled from Japan to Hawai'i on a seven-hour flight. When the flight landed, the U.S. Public Health Service (USPHS) Quarantine Station in Honolulu alerted passengers that a suspected case of measles had been identified, but they were not detained. The next day, to offer appropriate post-exposure prophylaxis, the Hawai'i Department of Health (HDOH) attempted to contact all passengers from the flight using information from the airline, U.S. Customs declaration forms, and tour agencies. Of 335 total passengers, 270 (81%) were successfully reached and provided complete information. The mean time from exposure to contact for all respondents was 61 hours (95% confidence interval 57, 66). A total of 202 (75%) of the responding passengers were contacted within 72 hours after exposure, the time period during which administration of measles vaccine would have provided protection for susceptible individuals. The time-to-contact was significantly longer for passengers who did not stay in hotels than for hotel guests. Customs forms proved to be of limited utility in contacting international travelers. This experience highlights the need for more complete and timely methods of contacting passengers potentially exposed to infectious agents aboard flights.