Planes prime danger spot for bugs

A passenger on a plane coughs into his handkerchief and half of what comes out of his mouth is covered - and the rest goes "everywhere".

That's just one example of how someone suffering from an infectious illness can spread the bug to dozens of other people on an aircraft.

An expert on infectious diseases, Professor Kurt Krause, yesterday said being in a closed place such as an aircraft meant the only real steps someone could take was to wear a respiratory mask - but even that could not be a guarantee of escaping infection.

The only way to be fully protected was if infectious people never boarded aircraft, Professor Krause said.

"If [an infected] person sneezes or coughs into a handkerchief 50 per cent of it will be caught and 50 per cent will go everywhere."

One infected person probably could not infect an entire plane-load of people but he or she could easily affect "dozens" of people, he said.

The professor, who is the director of the Webster Centre for Infectious Diseases at the University of Otago, said a virus such as the swine flu would spread like the common cold.

"Mucus being spread by coughing, not washing your hands and then handshaking are very much the cause," he said. That included surfaces such as armrests and door handles if hands had not been washed properly.

Ministry of Health director of public health Dr Mark Jacobs said flu virus could survive on surfaces for up to a couple of days.

An added problem for plane passengers was that they sat so close to each other and for such long periods of time.

An Air New Zealand spokeswoman said an air-conditioning unit on the company's aircraft filtered 99.999 per cent of airborne viruses, including influenza. Aircraft were also cleaned on arrival to a standard that complied with international requirements.

Professor Krause said that was encouraging to hear but it still wouldn't stop infection spreading by a carrier coughing directly on to someone or touching a surface, such as a toilet door, which was followed by the person rubbing their nose - and spreading the virus.

additional reporting Jacqueline Smith