People planning to travel during the summer holidays should take precautionary measures against infectious diseases and other travel-related illnesses, such as high-altitude syndrome.

Department of Health Chief Port Health Officer Dr Henry Kong said in view of the recent rise in Dengue fever in Southeast Asia, and human cases of avian influenza in Vietnam, Indonesia and Egypt, travellers should maintain good personal, food and environmental hygiene.

"This year, some of the countries in the region have recorded higher infection rates when compared with last year and the number of cases is expected to increase with the arrival of the rainy season," Dr Kong said.

Dengue fever is an endemic disease in Southeast Asian countries. The best way to prevent it is to avoid mosquito bites.

On avian influenza, Dr Kong urged travellers to avoid direct contact with chickens and their faeces, and to avoid farms. If contact has been made they should wash their hands thoroughly with soap and water as soon as possible.

High-altitude syndrome

On environmental health hazards, Dr Kong said high altitude syndrome in mountainous areas is a health risk to travellers.

It appears typically on rapid ascent to altitudes above 2,500 metres, such as flying or driving directly to Lhasa or Kilimanjaro. Symptoms of high altitude syndrome occur gradually after a few hours of ascent. The symptoms include headache, nausea, fatigue, dizziness, sleep difficulty, sudden awakening and a feeling of suffocation, irritability and loss of appetite, as well as swelling of the face, hands and feet.

Severe altitude sickness symptoms include changes in behaviour, disabling weakness, loss of co-ordination, breathlessness even at rest, and blue lips or fingernails.

Dr Kong said being young and fit offers no protection, adding that a slow ascent and adequate rest are essential. For more tips on preventing altitude sickness click here.