Mark Gendreau (Lahey Clinic Medical Centre, MA, USA) and colleagues reviewed data from studies looking at the transmission of diseases during commercial air travel. They found that while commercial airlines are a suitable environment for the spread of pathogens carried by passengers or crew, the environmental control systems used in commercial aircraft seem to restrict the spread of airborne pathogens. Proper ventilation within any confined space reduces the concentration of airborne organisms, with one air exchange removing 63% of airborne organisms suspended in that particular space. Computer models of data from an in-flight tuberculosis investigation reveal that doubling ventilation rate in the cabin reduced infection risk by half.
Investigations of in-flight transmission of tuberculosis suggest that the risk of disease transmission to other symptom-free passengers within the aircraft cabin is associated with sitting within two rows of a contagious passenger for a flight time of more than 8 hours. This is believed to be relevant to other airborne infectious diseases. However, in one outbreak of SARS, passengers as far as seven rows away from the source passenger were affected.
The review states that disinsection of aircraft - spraying before landing to kill insects - and vector control around airports, as well as immunisation, seem to have been effective in non-endemic areas. However, although International Health regulations recommend disinsecting aircraft travelling from countries with malaria and other vector-borne disease only five countries currently do so (Australia, Caribbean, India, Kiribati, and Uruguay).
The authors believe the aviation industry and medical community should educate the general public on health issues related to air travel and infection. They w rite that good hand hygiene has been proven to reduce the risk of disease transmission, and air travellers should make it part of their normal travel routine.
Dr Gendreau comments: "Because of the increasing ease and affordability of air travel and mobility of people, airborne, food-borne, vector-borne infectious diseases transmitted during commercial air travel are an important public health issue. Heightened fear of bioterrorism agents has cased health officials to re-examine the potential of these agents to be spread by air travel. The SARS outbreak of 2002 showed how air travel can have an important role in the rapid spread of newly emerging infections and could potentially even start pandemics. In addition to flight crew, public health officials and health care professionals have an important role in the management of infectious diseases transmitted on airlines and should be familiar with guidelines provided by local and international authorities."