Risk of norovirus transmission during air travel

BACKGROUND: During October 2006, an outbreak of norovirus gastroenteritis sickened 200 (59%) of the 379 passengers and 26 (18%) of the 144 crew members on a riverboat. In November 2006, CDC was notified that a group of ill passengers had boarded a commercial flight from St Louis, Missouri, to Atlanta, Georgia. A recent study demonstrated probable norovirus transmission from eight symptomatic flight attendants to passengers on board an aircraft during an international flight; however, there are no published reports of transmission of norovirus on flights of short duration.

METHODS: We investigated the risk of norovirus transmission on a short flight as part of an outbreak response. Using a standardized questionnaire, we conducted interviews of passengers and flight attendants who were on the flight. We collected information on traveler demographics and illness before, during, and after the flight. We also collected information about potential onboard risk factors for norovirus transmission, such as proximity and contact with ill appearing persons during the flight, as well as use of onboard lavatories and hand hygiene.

RESULTS: We were able to complete questionnaires for 50 (56%) of the 89 passengers on the flight and 2 (67%) of the 3 flight attendants. Two (5%) of 42 possible secondary cases were identified. These two passengers neither sat in proximity to an index-case passenger during the flight nor reported use of an onboard lavatory.

CONCLUSIONS: Although onboard transmission cannot be excluded, likelihood of norovirus transmission on a short flight when ill travelers do not have episodes of vomiting or diarrhea appears minimal.