Everyone sitting on an aircraft carrying a passenger infected with measles is at risk of contracting the disease - not just those sitting closest to the carrier, new research shows.
The study on the transmission of infectious measles on aircraft has raised questions about whether health authorities should continue to contact those seated close to a passenger who later discovered he or she had measles.
In the future, health authorities could use the media, email and mobile phone text messages to alert passengers on a plane that may have been exposed to measles.
Researchers looked at 45 cases of people infected with measles and who travelled on aircraft, as part of a study that will be presented on Wednesday at an Australasian Society for Infectious Diseases conference in Canberra.
It appeared the 45 people had infected 22 fellow passengers, most of whom had been seated further away than the two-row zone, which is usually the area that concerns health authorities.
Co-author of the study Gary Dowse, of the West Australian Health Department, said public health officials often struggled to contact passengers at risk of exposure so that preventive medication could be given to them in time, if they were not already immune to measles.
"Within 72 hours we can offer them a dose of vaccine and that might protect them. If it's within six days we can offer them immunoglobulin which is pre-made antibodies and that may protect them,'' Dr Dowse said.
"However, if we don't find out about the index case, or infected person for several days, we can't get the flight manifests and link that to customs cards to get contact phone numbers, [then] our efforts to provide vaccine or immunoglobulin will be in vain.''
Dr Dowse said passengers were only infected on 14 per cent of flights, probably due to high rates of vaccination and previous exposure to measles in Australia.
He said the most appropriate way to contact passengers who may have been exposed may be via the media or text messages.
People who contract measles generally do not display symptoms for about 10 days to 14 days.
"A general media alert is not necessarily going to be seen or heard by everyone who was on a plane but it might actually get to more people and in a more timely way than us trying to contact that defined sub-group, who are seated within two rows.''