Transmission of infectious diseases during commercial air travel

is the subject of a review in last week's Lancet (only available to subscribers, ref: Lancet 365:989).

Overall, it is reassuring, with few documented cases of infection and less airborne transmission than one might expect. The airflow they describe is mostly top to bottom, which limits spread among passengers

data suggest that risk of disease transmission to othersymptom-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 h

Unfortunately there are exceptions and SARS seems to be one of them.

Overall it seems the biggest public health risk is moving infected people rapidly from place to place rather than infections acquired while travelling.

One cool thing most people probably don't know is that there are sporadic cases of malaria around airports in non-endemic areas (like the US) transmitted by mosquitoes who hitch a ride on international flights and then take up residence. Luckily, this hasn't led to establishment of endemic infection anywhere (yet).