FACTBOX-Swine flu raises air travel health concerns

April 28 (Reuters) - The World Health Organisation is not recommending any travel restrictions to contain an outbreak of swine flu that has killed people in Mexico and spread around the world.Countries worldwide have ramped up their border and airport checks and many are advising against non-essential travel to areas where the virus has been found, especially Mexico where it has proved most deadly.Following are the health concerns related to air travel, and guidance from the WHO and the international airlines body IATA about how travellers should stay safe and what carriers should do to reduce disease transmission risks:WHAT SHOULD TRAVELLERS DO?-- Wash hands frequently-- Avoid contact with sick persons-- Avoid contact with live animals in markets-- Consult with doctor before travelling if illDOES VIRUS SPREAD ABOARD AIRCRAFT?Germs can circulate in plane cabins, although IATA says that modern aircraft have advanced filtration systems which have markedly improved the level of on-board air quality.WHO experts have previously said that transmission risks for diseases such as tuberculosis are only highly acute on flights lasting more than eight hours, and for people sitting within five rows of an infected person