MANILA, Philippines ? Perfumes, which some people use to attract the opposite sex, give off hundreds of scents that dengue- and malaria-transmitting mosquitoes just love, an entomologist said on Tuesday.

Doctor Estrella Cruz, an entomologist at the Research Institute of Tropical Medicine, said people who spray on too much perfume, body sprays and cologne, those who sweat profusely and those who wear dark clothes, shorts and sleeveless shirts were more attractive to mosquitoes.

?Mosquitoes have hundreds of stimuli. They can smell humans, more so if one sprays perfume. The same is true when you are sweating,? Cruz said at a health forum on ?Balancing the Department of Health's Actions on Dengue? sponsored by the Philippine College of Physicians in Quezon City.

The Department of Health has said that dengue, a mosquito-borne disease, has so far afflicted more than 50,000 people, killing 500 of them. Most of the affected are children and those with weak immune system.

Cruz said a male mosquito has a life span of 8-10 days while the female can live up to 30 days.

While an infected female mosquito can transfer dengue to humans, an infected human can also infect a non-infected mosquito once it bites him/her, she said.

There are two types of dengue mosquitoes in the Philippines ? the Aedes aegypti and the Aedes albopictus. Both are domestic species as they live close to humans. A. aegypti dwells in houses, mostly in dark places like closets and under furniture, while A. albopictus lives outside, usually in containers or plants where water collects.

Although dengue mosquitoes are day-biting insects, Cruz said that they could also bite at night although at a very low density level. Peak biting is early morning, or between 6 a.m. to 8 a.m. and late afternoon or sunset between 4 p.m. to 6 p.m.

Cruz said it was very important to know about the peak biting time of mosquitoes for effective control measures like fogging. She warned against fogging during rainy or hot days as the chemical being used to kill the mosquitoes would just disintegrate.

Doctor Hazel Galang, an RITM virologist, said there were four strains of dengue virus in the Philippines.

News about a possible fifth strain has surfaced in the country but Galang said this has not been proven by research as there have not been enough samples to date.

Since 2005, she said, the RITM has been trying to determine which specific strains of dengue virus are unique to the Philippines and which are from other countries.

A person with dengue should not always be subjected to blood transfusion, said Dr. Allan Racho, a pediatric hematologist at the St. Luke's Medical Center.

Racho said that dengue fever was graded 1-4, according to severity.

As such, blood transfusion should not be an immediate procedure in the treatment of dengue cases but only in grade 3 or 4 cases as determined by laboratory tests.

Racho said that a person with fever or with dengue under grade 1 to 2 cases could stay at home and take paracetamol and plenty of fluids. Or they can be administered with just dextrose in health centers or hospitals even if their platelet count is low.

?Dengue primarily is a transient disease, meaning it follows its own clinical force. The problem with dengue is not dengue itself but the complications that set in,? Racho stressed.

He said the virus primarily affects the body?s three main systems ? the vascular system, the liver, and the bone marrow. In some instances, the virus can attack the heart, brain and other parts of the body which can lead to death.

To be sure, he said, a person with fever that did not disappear in three days must see a doctor and undergo testing.

Engineer Nuna Almanzar of the Industrial Development Institute-Department of Science and Technology developed for the institute a dark mosquito trap with a specially formulated solution that attracts female mosquitoes.

In the same forum, Almanzar said the trap was now being tested in 500 homes in dengue ?hot spot? villages in Marikina and another 500 homes in Quezon City.

Almanzar said that a female mosquito could lay eggs three to four times in a cycle, and can breed 200 eggs or 800 eggs in one cycle. Of these eggs, about 80 percent develop into female mosquitoes.