Australasian Science: Australia's authority on science since 1938

Business Class Is Not a Barrier to Measles

By Stephen Luntz

Measles is a threat to airline passengers beyond the immediately surrounding rows, an Australian study suggests, requiring a rethink of prevention measures when an infectious person has been on a flight.

Dr Gary Dowse of the Communicable Disease Control Directorate explains: “Air on airplanes circulates sideways and is replenished every few minutes, so the theory was that people most at threat from airborne diseases were likely to be sitting in the same or nearby rows”.

However, when Dowse obtained information on measles cases linked to flights to or within Australia from 2007–11 he found 45 examples of infectious individuals travelling by air with 20 secondary cases among passengers. “We can be confident that these infections were caused by being on the flight because we have no endemic measles transmission in Australia and the timing is right for people to have caught it on the flight,” Dowse says.

Of these 20 secondary cases only nine were seated within two rows of the infectious individual. “People move around the cabin, and they might cough or sneeze in the toilet and infect the next person who uses it,” Dowse says. “Infection could also take place in the check-in queue or at the baggage carousel.”

Moreover, Dowse warns that the information required to contact passengers seated near an infectious individual is usually not available in time to be effective. “If we can get to someone who is not immune to measles within 3 days of infection we can give them the MMR vaccine, or within 6 days we can give them immunoglobulin,” Dowse says. Unfortunately “because of delays in diagnosis and notification of cases, and the additional time to access flight information, only 31% of flight manifests were available to health authorities within 5 days of travelling”.

As it is, attempting to contact everyone seated within two rows of an infectious individual is a major drain on the resources of communicable disease units, and Dowse says that expanding this to eight rows in front or behind – which would cover most infected passengers – would be impractical and too late to be effective.

Instead, Dowse suggests general media alerts, or SMS/email messages if airlines have passenger contact information, should be issued to warn everyone on a particular flight to watch for symptoms. “We should advise people who become ill to call their doctor beforehand rather than infecting everyone in the waiting room,” Dowse says.

Dowse’s work is likely to prove even more relevant for diseases such as influenza that are also spread through airborne droplets and have shorter incubation periods.