The Department of Health confirmed today one more imported case of Dengue fever, which involved a 46-year-old man. So far, 25 Dengue fever cases have been reported in Hong Kong - all imported.

The patient developed fever, cough, vomiting and diarrhoea on August 2, a day after returning from a South Asian country. On August 7, he was admitted to Princess Margaret Hospital with a rash on his trunk and limbs.

Based on the clinical features and laboratory tests results, the patient was found to be suffering from Dengue haemorrhagic fever. He is now in stable condition.

The department called on the public to remain on guard against mosquitoes and Dengue fever by actively eliminating mosquito breeding sites and taking precautions.

Dengue fever is a viral illness transmitted by the bite of the infectious Aedes mosquito. The Dengue viruses include four serotypes.

While recovery from an initial infection caused by one serotype provides lifelong immunity against the serotype only, subsequent infection by another serotype of the Dengue virus increases the risk of acquiring the more serious disease, Dengue haemorrhagic fever.

Most patients can recover with proper treatment.

Here are some tips to guard against mosquito breeding:

* put all used cans and bottles in covered dustbins;

* change water for plants at least once a week, leaving no water in the saucers underneath flower pots;

* cover tightly all water containers, wells and water storage tanks; and

* keep all drains clear.

Travellers should take preventive measures against Dengue fever:

* wear long-sleeved clothes and long trousers;

* use insect repellent over the exposed parts of the body; and

* use mosquito screens or nets when the room is not air-conditioned.