19 April 2010
FAITH LAPIDUS: This is SCIENCE IN THE NEWS in VOA Special English. I’m Faith Lapidus.
BOB DOUGHTY: And I’m Bob Doughty. Today we will tell about the disease malaria and efforts to defeat it. Scientists say progress in medical research could reduce the number and severity of malaria cases worldwide.
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FAITH LAPIDUS: World Malaria Day activities are planned in many countries this Sunday. The events will call attention to the disease and international efforts against it.
This is the third year that World Malaria Day has been observed. It is also an important year in the fight against malaria. The international malaria community has set the end of twenty-ten as its target for meeting the first in a series of goals.
One of the goals is to provide protection, medical diagnosis and treatment for every person at risk of malaria. A second goal is for the number of malaria cases and deaths to be reduced by fifty percent or more from the number reported in two thousand.
BOB DOUGHTY: The World Health Organization estimates that more than three billion people live in areas where malaria is a threat. That represents more than half of the world’s population. America’s Centers for Disease Control and Prevention says the disease will infect three hundred fifty million to five hundred million people around the world this year. Each year, malaria kills about nine hundred thousand people worldwide. Those surviving are often left brain damaged, blind or with hearing loss.
FAITH LAPIDUS: Most cases of malaria are in African countries, south of one of the world’s biggest deserts – The Sahara. The World Health Organization says the disease is responsible for one in five childhood deaths there. Malaria kills about two hundred thousand children in Africa every year, an average of one every thirty seconds.
Malaria is also a threat to people living in parts of Asia, Central and South America, the Middle East, and southeastern Europe. People from malaria-free countries who visit areas with high rates of malaria are also very much at risk. This is because their bodies have little or no resistance to the disease.
BOB DOUGHTY: The cause of malaria is a parasite called Plasmodium. Mosquitoes infected with Plasmodium spread the disease to human beings through mosquito bites. The parasites reproduce in the human liver, and then infect the red blood cells. After they enter the blood cells, they reproduce again. As they do this, they destroy the cells.
Signs of the disease appear in victims ten to fifteen days after they are bitten. People with malaria develop a high body temperature. They also can become weak, expel material from the stomach, and suffer pain in the head or muscles. If not treated, malaria can make the victim very sick and even cause death.
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FAITH LAPIDUS: Late last year, researchers in the United States met to discuss developments in malaria research. One sign of hope is a new way to make the natural defenses of mosquitoes resistant to the Plasmodium parasite.
George Dimopoulos is an associate professor at the Johns Hopkins Malaria Research Institute. His team used a method called transient gene silencing to change the genetic structure of the three mosquito species responsible for spreading malaria. The genetic changes cause the bodies of the insects to attack the Plasmodium parasite, blocking its development.
BOB DOUGHTY: Gregory Glass is a professor with the John Hopkins Bloomberg School of Public Health. His team used satellite imaging to observe mosquito populations in Africa. The closer one lives to places where mosquitoes reproduce, the greater the risk of getting malaria.
Professor Glass says the satellite imaging helps researchers identify which areas face the greatest risk. He says it also shows where to send much-needed medicines, insecticide products and protective mosquito nets.
FAITH LAPIDUS: The Malaria Institute at Macha in southern Zambia is a living laboratory for the study of mosquito and human behavior. There, researchers are developing a test that uses human saliva instead of blood to find those infected with malaria. The researchers say the test will make it easier to identify and contain the disease, especially in children. It would also be helpful in areas like southern Africa, where people often do not show signs of the disease.
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BOB DOUGHTY:
For years, researchers have been working to develop a vaccine against malaria. Those efforts have greatly increased in recent years. There are now more than fifty experimental vaccines in existence.
The world’s largest malaria vaccine study began last year in seven African countries. It is the result of more than twenty years of research and ten years of clinical testing. The study is to involve up to sixteen thousand children. They live in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania.
GlaxoSmithKline Biologicals developed the vaccine, known as RTS,S. It is the first malaria vaccine candidate to have large success during early testing. It is also the first vaccine designed mainly for use in Africa.
FAITH LAPIDUS: A recent study showed that RTS,S reduced clinical cases of malaria by fifty-three percent over an eight month follow-up period. In another study, the vaccine was effective in reducing clinical malaria by thirty-five percent. It also reduced cases of severe malaria by forty-nine percent.
Two weeks ago, a Dutch drug-maker, Crucell, announced it will work with GlaxoSmithKline to jointly develop a new malaria vaccine candidate. The vaccine candidate is to be made from two drugs the companies are developing separately. Crucell says studies have shown the drugs may work better when combined than they do independently.
BOB DOUGHTY: Last year, another drug company, Sanaria, won a Vaccine Industry Excellence Award for Best Early Stage Vaccine for its malaria vaccine. The Sanaria vaccine is unlike other malaria vaccines being developed. It is a live vaccine, made of a weakened version of the whole malaria parasite.
Scientists at Sanaria use non-malaria carrying mosquitoes to develop their vaccine. They feed the insects blood containing the malaria parasite. They then use radiation to weaken the parasite, which is then harvested for the vaccine.
In an earlier study, the scientists at Sanaria used live mosquitoes to deliver the vaccine. Thirteen of fourteen volunteers were completely protected against malaria after receiving the vaccine. They also remained protected for at least ten months. Sanaria is now preparing to ask the United States Food and Drug Administration for approval to begin federal testing of the vaccine.
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FAITH LAPIDUS: For now, the main effort to control malaria involves treatment of bed nets and indoor living areas with insecticides -- products used to kill insects.
The World Health Organization says insecticide use has greatly reduced the number of malaria cases. The W.H.O. says insecticide-treated bed nets have been shown to reduce the number of malaria cases by fifty percent and the infection rate by ninety percent.
The United Nations agency released its World Malaria Report in December. The report said home ownership of insecticide-treated nets had reached fifty percent in thirteen of the thirty-five African countries with the highest cases of malaria. It also said more than one third of all countries at risk of malaria reported a drop in cases of more than fifty percent.
BOB DOUGHTY: Early identification and drug treatment of malaria can reduce the severity of the disease and prevent death. The anti-malarial drug Chloroquine was widely used until recent years when the malaria parasite became resistant to the drug. Now, the World Health Organization advises use of Artemisinin-based combination treatments, or ACTs, for malaria patients.
The W.H.O. says the international community is now in a position to defeat malaria. It says that, with the use of insecticides, better testing and drug treatments, the world could reach its goal of zero malaria deaths by twenty fifteen. Still, it says, there is an immediate need for the international community to continue and increase its investment in the fight against malaria.
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FAITH LAPIDUS: This SCIENCE IN THE NEWS was written by June Simms. Our producer was Mario Ritter. I’m Faith Lapidus.
BOB DOUGHTY: And, I’m Bob Doughty. Listen again next week for more news about science, in Special English, on the Voice of America.