COTABATO CITY, Philippines -- A ranking health official has appealed to people to spare spiders, lizards, frogs and other animals that prey on mosquitoes following a warning by the World Health Organization (WHO) about the rising incidence of dengue in many parts of Asia, including the Philippines.

Dr. Paulyn Jean Ubial, Mindanao coordinator of the Department of Health (DoH), said the protection and preservation of mosquito predators would help in the fight against dengue.

Dengue is caused by a virus transmitted by some species of day-biting mosquitoes, including the Aedis egypti, or what are commonly known as tiger mosquitoes.

Dengue can be fatal, especially if detected late.

"Frogs, lizards and spiders prey on mosquitoes and there's a need to preserve these creatures to help us control this health menace to humans," Ubial said.

Ubial said the predators are especially helpful at this time, when mosquitoes appear to have built a resistance to chemical insecticides.

She noted that fogging in areas where dengue is endemic has failed to control the mosquito population.

Ubial, who was here Thursday for the yearly launching of the anti-dengue campaign in the Autonomous Region in Muslim Mindanao (ARMM), said if humans are vulnerable to mosquito bites, mosquitoes are also vulnerable to frogs, lizards and spiders.

She said unless these natural mosquito predators are protected, the fight against dengue would not succeed.

In the ARMM alone, the number of dengue cases increased to more than 500 in 2007, from only about 350 in 2006.

This year, 10 dengue cases, one fatal, have been recorded in Shariff Kabunsuan province alone.

Dr. Tahir Sulaik, ARMM health secretary, said sanitation is among the most effective ways to reduce the population of mosquitoes, which also transmit other potentially fatal diseases, including malaria.

"A clean surrounding devoid of water-filled containers and stagnant water, which are considered favorite breeding places of mosquitoes, is a must," he said.