Newsfeed display by CaRP MALARIA-CARRYING mosquitoes have plagued the human race for a long time. As well as despite the knowledge humans have gained about this tiny winged insect and the deadly single-celled parasite it could potentially transmit to humans, the World Health Organization estimates that each year 300 million to 500 million cases of malaria still occur.

"Usually mosquito bites are a harmless nuisance. But when the insect carries parasites that cause malaria, just one bite spells trouble," says Doctor Mario Baquilod, division chief of the Department of Health Infectious Diseases Office. Further Dr. Baquilod explains, however, that the chances of contracting malaria will only increase if one goes to a defined geographic area where the parasites and the mosquito species that transmit them are confined.

"The risk of acquiring malaria is also determined by the intensity of malaria transmission in the area and season of one's visit to the area, as well as the length of stay, type of accommodation and likely activities between dusk and dawn," says Baquilod. This is why Baquilod advises people who are going to any of these places, especially during the rainy season to take chemoprophylaxis -- usually the inexpensive doxycycline -- as a precaution two or three days before travel. The drug has to be taken daily up to four weeks after one leaves the place.

Although no prophylaxis is 100 percent effective, the correct medicine will reduce one's risk of contracting severe illness, he says.

According to DOH entomologist Norma Joson, malaria is caused by four species of the Plasmodium parasite, namely P. falciparum, P. vivax, P. malariae and P. ovale. Only the first two are endemic to the Philippines. The parasite is primarily transmitted by the two species of Anopheles mosquito native to this country, the Anopheles flavirostris complex and the Anopheles maculatus complex.

In the Philippines over 70 percent of malaria infections are due to P. falciparum infection.

Only the female Anopheles mosquitoes transmit malaria, as only female mosquitoes bite humans to take a blood meal. The Anopheles are mostly found in the clear running water of mountain streams, either well exposed to the sun or along a more shady edge, in seepage water, springs and shallow wells.

When the malaria-carrying mosquito bites a human, it injects the malaria parasites into the person's blood. The parasites travel through the person's bloodstream to the liver, where they grow to their next stage of development.

In six to nine days, the parasites leave the liver and enter the bloodstream again. They invade the red blood cells, and begin to multiply quickly, causing the blood cells to burst. The infection spreads and the person starts experiencing malaria symptoms. On the other hand, when a non-infected Anopheles mosquito bites a person infected with malaria, the mosquito sucks up parasites from the person's blood. The mosquito is then infected with the malaria parasites, which go through several stages of growth inside the mosquito.

The early symptoms of malaria include flu, with periods of chills and fever lasting several hours and occurring every few days. When one experiences this, it is best to immediately seek medical attention.

Without treatment, the illness may deteriorate rapidly, especially in high-risk groups including pregnant women, young children, and immune-compromised patients.

The best way to beat malaria is to prevent contact with the mosquitoes, in the first place.

"The malaria parasite has proven to be insidious, managing to mutate and resist drugs and insecticides created to fight it. Even scientists looking for a cure for malaria admit that it may take several more years to create a vaccine that provides total protection," says Baquilod.

As part of the nationwide Malaria Control Program, the DOH, in coordination with its local partners, conducts awareness campaigns in endemic areas, does house-to-house insecticide spraying operations during outbreaks, and distributes mosquito nets impregnated with insecticides to families living in high-risk areas. "We also advise them to wear long-sleeved shirts or blouses and long trousers to protect their arms and legs, especially from dusk to dawn when these malaria-carrying mosquitoes are out," Baquilod says.