Part of the problem is that the unicelled malaria parasites, called plasmodia, lead complex lives. When an infected mosquito bites, it injects parasites into the bloodstream. The plasmodia lodge in the liver, where each soon multiplies 40,000 times. These in turn invade red blood cells, multiply again and so on, causing fever and chills.
In most cases, drugs can treat the disease. That's why only 33 people died of malaria in the Solomon Islands last year, although nearly 42% of the 300,000 residents suffered from the disease. That's nearly double the rate of four years ago.
Reasons for the increase are easy to find. Most DDT spraying stopped. Government raises cut into the health budget. Foreign aid money for supplies dried up. Fights between central and provincial health officials left a bureaucratic stalemate. The result was disaster.
"There was a cessation of all malaria control activities," said Dr. Jayan Velayudhan, the WHO liaison officer in Honiara.
So Solomon Islanders make do. Health workers recently distributed 120 mosquito nets doused with permethrin, an insecticide, to residents in Vutu, a simple seaside village of thatched huts on wooden stilts about 12 miles north of Honiara.
But the nets are only partly effective. The coastal mosquito, Anopheles farauti, bites for two hours at dawn and again at dusk, precisely when villagers are cooking and drawing water outside.
"We have a hard time controlling it," said Bernard Bakote, a government entomologist. "It's a social problem. The people get together and gossip, and the farauti are very happy."
Not so the people. Barnabus Bana, a 47-year-old farmer, had malaria three times last year. So did his wife and four of their seven children. Each time, they took chloroquine until the fevers and shivering had passed.
"I feel pain, aches all over," he recalled, describing the disease. "My body is weak. Sometimes I vomit. Inside I'm hot, outside I'm cold."
Now his 15-year-old son, Garnett, sleeps under a net in the early morning heat. Nearby, tacked to the porch wall, a faded poster shows a huge, bloodthirsty mosquito. "WANTED DEAD: Ms. Anopheline," it reads. "Crime: Brought death and suffering to most Solomon Islanders."
Reprise of Ancient Scourge The Problem: Malaria describes a group of parasitic blood diseases that have caused sickness and death since ancient times. The word derives from Italian, meaning "bad air."
Transmission: The culprit is a microscopic, one-celled parasite of the genus Plasmodium that is passed from an infected person to an uninfected one through the bite of a female Anopheles mosquito.
Symptoms may include:
* repeated attacks of violent shaking and chills
* fever as high as 106 degrees F
* severe headaches
* profuse sweating
* enlargement of the spleen
* severe anemia
* muscular pain
May occur in two- or three-day cycles, depending on which of four strains is involved.
Treatment: The drug chloroquine is the primary treatment. Certain strains also require primoquine to combat liver infections. Where the organism has become resistant to treatment with chloroquine, three drugs must be used together: quinine, pyrimethamine, and a sulfa drug. An infected mosquito injects Plasmodia with its bite.
Each Plasmodium invades a liver cell and multiplies.
The cell bursts, releasing a new form of Plasmodia.
Each Plasmodium enters a red blood cell and multiplies.
Cell ruptures, and Plasmodia invade more red cells.
Some Plasmodia are able to infect mosquitoes.
Prevention: * Take chloroquine before entering and for six weeks after leaving infected regions.
* Use insect repellent and mosquito netting to reduce the likelihood of being bitten by infected mosquitoes. * Spray with insecticides such as DDT and drain marshes and other areas of stagnant water where mosquitoes breed.
Reported malaria cases (in thousands) 1981-1988(1)
1981 1982 1983 1984 1985 1986 1987 Africa(2) 6,754 6,042 2,726 4,523 11,634 17,472 19,463 Americas 638 718 831 931 911 951 1,019 Eastern Mediterranean 207 308 305 335 391 610 565 Europe 60 66 73 62 57 47 28 South-East Asia 3,566 2,964 2,731 3,004 2,503 2,689 2,823 Western Pacific 3,464 2,487 1,839 1,410 1,178 1,012 893
1988 Africa(2) 21,957 Americas 1,120 Eastern Mediterranean 602 Europe 24 South-East Asia 2,789 Western Pacific 774
notes: 1 - The information provided is not complete in some instances.
2 - Figures for Africa are estimates because most countries do not have formal reporting systems in place.
Sources: World Health Organization, McGraw-Hill Encyclopedia of Science and Technology, World Book.