SCIENCE IN THE NEWS in VOA Special English.
I’m Bob Doughty.
And I’m Faith Lapidus.
Today we tell about malaria. The
disease threatens people in more than one hundred countries.
United States Centers for Disease Control says up to five hundred million
people worldwide get malaria each year.
The disease kills more than one million malaria patients every year. Many victims are young children in southern
Malaria also strikes parts of Asia, the Middle East, Central
and South America, Hispaniola and islands of the Pacific Ocean.
Early identification and treatment can
shorten the sickness and prevent damage to the body’s organs. But many countries that report malaria cases
do not have enough money to support campaigns against the disease. And malaria itself resists attempts to
The Bill and Melinda Gates Foundation
has given more than one billion dollars to fight malaria. Last year, Mister and Missus Gates said the
international health community should attempt to permanently end the threat
from the disease. The head of the World
Health Organization supports the Gates’ goal.
W.H.O. director general Doctor Margaret Chan has urged other experts to
attempt to defeat the disease.
only one communicable disease, smallpox, has ever completely disappeared. Some experts are not sure malaria should be
attacked with the goal of destroying it.
They say earlier such efforts led to unrealistic hopes, but then failed.
of the W.H.O.’s anti-malaria program says current methods could reduce malaria
cases by ninety percent. Doctor Arata
Kochi said this could happen if enough resources were available to fight the
common insect, the mosquito, spreads malaria.
Thecarries the parasite that causes the
disease. Very small parasites develop
in the stomach of the mosquito.
Parasites are organisms that live on or in another animal and get their
food from that animal.
general name for the malaria parasite is Plasmodium. Mosquitoes pass the parasites to people when they drink blood
through the skin. However, only the
female Anopheles mosquitoes drink blood.
The males feed only on liquids from plants.
female Anopheles mosquito drinks blood from people and animals by breaking
through the skin with its long, tube-like feeding device. The parasites enter the blood of the
blood carries the parasites to the victim's liver. From there they invade cells and reproduce. After nine to sixteen days, the parasites
return to the blood and enter the red blood cells. Then they reproduce again.
As they do this, they destroy the blood cells. In a short time, the victim develops a high body
temperature. The victim becomes weak
and is unable to carry out normal activities.
signs of malaria include pain in the muscles or head and shaking. Patients with severe malaria may develop
liver and kidney failure, seizures and become unable to communicate.
of malaria have been observed since the beginning of history. Scientists examining bodies of ancient
Egyptians have found evidence of the disease in people who lived at least three
thousand years ago. And scientists have
found hardened remains of mosquitoes millions of years old.
one time, it was believed that bad air caused malaria. People believed this bad air came from areas
of water that were not deep and did not move.
It seemed that malaria was most common near these swamps.
people suspected that mosquitoes were linked to malaria. The Greek historian Herodotus lived about
two thousand four hundred years ago. He
noted that in swampy areas of Egypt, some people slept in tall structures where
mosquitoes could not go. Or they slept
under nets that mosquitoes could not go through.
In eighteen seventy-six, British
scientist Patrick Manson discovered that mosquitoes were responsible for
passing the disease to human beings.
More exactly, he found that insects carry the parasites and pass them to
eighteen eighty, a French doctor, Alphonse Laveran, discovered that the
Plasmodium parasite causes the disease.
In eighteen ninety-seven, a British scientist, Ronald Ross, found the
malaria parasite in the Anopheles mosquito.
For his discovery of the cause of
malaria and other work, Doctor Laveran received the Nobel Prize for Medicine in
nineteen-oh-seven. Five years earlier,
Mister Ross received the Nobel Prize for Medicine for his work on malaria.
The discoveries of the three scientists
soon led to efforts to control malaria.
Then, the discovery of the insect poison D-D-T led to efforts to destroy
Between nineteen fifty-five and nineteen
sixty-nine, the World Health Organization organized campaigns against the
disease. The goal was to use chemicals
to kill mosquitoes in homes around the world.
effort was successful in large areas of North America, southern Europe, the
former Soviet Union and some parts of Asia and South America. The spread of the disease in these areas was
the disease remained in Central America, parts of South America, and some Asian
countries. A W.H.O. campaign never was
attempted in Africa. It was too
difficult and costly for most African countries.
nineteen sixty-eight, malaria suddenly spread in Sri Lanka, where it was
believed the disease no longer existed.
At the time, the island nation was known as Ceylon. Malaria also spread in Central America, in
Southeast Asian nations, and in parts of Africa.
to destroy the disease throughout the world were suspended in nineteen sixty-nine.
There are four different kinds of
malaria. They are caused by four
different kinds of parasites. Three of
them cause victims to suffer high body temperatures every few days. But they do not cause death. However, the most common malaria parasite
also is the most dangerous. This
parasite causes infections that can lead to death.
The best way to prevent malaria is to
stay away from the mosquitoes that carry the malaria parasites. The female Anopheles mosquito takes blood
from its victims mainly at night.
people can place material specially treated with insect poison over their beds
while they sleep. People can also put
anti-insect chemicals on their skin, on clothing and in sleeping areas. They can wear clothes that cover most of the
the mosquitoes get past barriers used to block them, early drug treatment is
needed to be effective. Drugs can
destroy the malaria parasite as soon as it enters the human body. This prevents the parasites from entering
the red blood cells and dividing. Some
drugs can prevent the parasite from establishing itself in the liver.
study found that a protein could provide a way to block the parasite’s actions
in the mosquito. The protein would act
before the mosquito can infect a human victim.
Health Infectious Diseases Research Team at the University of Florida carried
out the study.
the fifteenth century, people in what is now Peru knew the covering or bark
from the cinchona tree was effective in treating signs of malaria. In eighteen-twenty, two French scientists
identified the substance in the bark as quinine. Until the twentieth century, quinine was the chief drug used to
prevent and cure some forms of malaria.
Today, manufactured drugs treat the disease. The World Health Organization says combination treatments are
best for common malaria.
A new drug meant for common malaria is
now being launched in Latin America and Southeast Asia. The medicine, known as ASMQ, combines two
Brazilian government and a not-for-profit organization are making the new drug
available to public agencies. Bernard
Pecoul heads the organization, The Drugs for Neglected Diseases
Initiative. He says ASMQ reduces the
number of pills the patient needs to remember to swallow. Doctor Pecoul says the treatment is safe,
fast-acting and effective for children and adults.
SCIENCE IN THE NEWS program was written by Jerilyn Watson. Our producer was Brianna Blake. I’m Bob Doughty.
I’m Faith Lapidus. Read and listen to
our programs at voaspecialenglish.com. Join us
at this time next week for more news about science on the Voice of