By Suzanna Pilay

MORE than one billion passengers travel by air each year.

Fifty million of them travel to the developing world. The popularity of budget travel has and will continue to help     many travel worldwide. There is a growing demand for shorter trips often using low-cost, low-fare airlines, concluded participants at the 2007 Pisa Forum for travel.

While this is good for the leisure industry, the view from a health standpoint is slightly different. With the increasing ease and affordability of air travel today, a person with an infectious disease can travel to virtually any part of the world within 24 hours. There is a risk of diseases transmission during, before and after air travel which means that in the future, outbreaks of new communicable disease could surface anywhere and potentially spread on an international scale.

An aircraft can also transport infected disease vectors such as rats (rabies) or mosquitoes (malaria, dengue).
Why is this significant to Malaysians? Every year, an estimated five million Malaysians cross international borders, especially to Asian countries where communicable diseases are prevalent.

But while many enjoy budget travel, few seek pre-travel health advice according to Sanofi Pasteur Malaysia, the vaccines division of the Sanofi Aventis group.

Sanofi Pasteur Malaysia medical manager Dr Jeyashree Jacob said it is often perceived that travelling in a ventilated, yet enclosed area such as an aircraft cabin increases the risk of infection from a communicable disease because of its "close proximity" environment.

"Most of the worry about spread of disease in an aircraft is the perception that the ventilation system (which uses 50 per cent re-circulated air and draws the other 50 per cent from the outside) would disseminate the organisms throughout the air cabin, but there have been no peer-reviewed scientific work that link a heightened risk of this happening compared with other modes of transport or with office buildings.

"At cruising altitude, the air is presumed to be sterile, while the re-circulated air is passed through a high efficiency particulate air filter."

But Dr Jeyashree noted that catching an infectious disease in an air cabin is probably a greater risk for passengers in close proximity with an infected person, who releases droplets of bodily fluid (through sneezing or coughing) into the cabin.

Other factors include the infectiousness (contagiousness) of the source, the ability of the organism to cause disease (pathogenicity), the duration of the exposure and the environmental condition in the plane and host-specific factors such as the general health and well-being of the person.

"Studies suggest that risk of disease transmission to other symptom-free passengers within the aircraft cabin is associated with sitting within two rows of a contagious person for a flight time of more than eight hours.

"Though this data is derived mainly from studies dealing with the transmission of tuberculosis, it is believed to be relevant to other airborne diseases.

"Some of the other airborne diseases that could be transmitted would be measles, influenza and the common cold, which have not been reported due to the difficulties of accessing and investigating the outbreaks accurately."

Food and water-borne diseases are the most commonly reported on an aircraft, especially an outbreak of salmonella. "Most of the reported cases were due to diseases caused by bacteria. However, it is noted that no food or water-borne outbreaks have been reported in the past five years.

"This could be attributable to greater use of pre-packaged frozen meals and improved food handling. Diseases by vectors are important for the importation of diseases. For example, the Aedes mosquito has been introduced in countries where it had not previously been present and may have likely been spread by air travel/"

Travellers can also pick up infectious diseases at places where they visit or stay such as sub-standard hotels, guest houses or hostels.

"Budget travel not only includes low-cost air travel but also travelling on a budget - which means restricted choices of where to stay, where and what to eat and how to travel.

"Sub-standard accommodations may mean reduced levels of cleanliness, overcrowding (especially with younger travellers living in hostels) and preparation of food that could be unsanitary, which are ways in which a contagious diseases, such as Hepatitis A, typhoid (in countries where it is endemic), influenza and traveller's diarrhoea, can easily spread."

The risk of becoming infected depends on the presence of the infectious agents in the area visited.

Eating hygienic, properly prepared food when travelling is also important as some infectious diseases are food-borne.

At high-risk are backpackers who travel on the cheap. The quality and amount of food they eat may be compromised at times.

"Stay hydrated and eat at places that have a good standard of cleanliness. Avoid drinking water unless it is boiled and, don't take ice in your drinks. Stick to bottled, tinned or pre-packed drinks.

"Carry disinfectant wipes for cleaning hands before eating and don't eat uncooked food and raw seafood.

"Living in cheap accommodations will also make backpackers more at risk of developing disease spread by mosquitoes, ticks and other vectors."

If you are bent on staying in budget lodgings, Dr Sharon Sim, occupational health doctor and head of department of the health and screening centre of a private hospital, suggests checking that the cleanliness and sanitation is acceptable and using insect repellents.

Before embarking on any form of travel, she recommends consulting your doctor regarding vaccinations for travellers.

"All international travellers (including children) should be up-to-date on immunisations regardless of the destination. They are encouraged to carry copies of their immunisation records with them when they travel."

-The New Straits Times