SCIENCE IN THE NEWS #2103 - Digest
By StaffThis is Bob Doughty.And this is Ray Freeman with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about a new medicine to prevent the disease caused by the Ebola virus. We tell about a deadly disease that may be spread by kissing. And we tell about a natural way to control a harmful insect.American researchers say they have developed a vaccine medicine that protected monkeys against the disease caused by the Ebola virus.
The Ebola virus affects animals and people. It causes the disease called Ebola hemorrhagic fever. No medicine or treatment exists for this disease. The disease kills fifty to ninety percent of the people it infects. It killed more than two-hundred people in the former Zaire in Nineteen-Ninety-Five. It has killed more than one-hundred-fifty people in Uganda since late September.
The Ebola virus kills so quickly that the body's defense system has no time to act against it. The disease begins with high body temperature, severe headache and muscle pain. Then it causes severe bleeding and failure of the organs. Then the victim dies. Doctors say a person with the Ebola virus usually dies within three weeks of becoming infected. It can spread to other people by touching victims of the disease.Two years ago, researchers developed a vaccine that protected small animals called guinea pigs from the Ebola virus. The scientists also used Ebola virus genes to make the new vaccine. Researchers at the National Institutes of Health near Washington, D. C. reported the results of this new experiment in the publication "Nature."
The research involved eight monkeys. Scientists gave the experimental vaccine to only four of the monkeys. They gave a deadly but small amount of Ebola virus to all of the monkeys. All the monkeys that did not get the vaccine died within a week. Those that got the vaccine survived. Three showed no signs of the disease. One was sick for a short time. All four monkeys were healthy six months later.The researchers say this is the first time a vaccine has protected animals similar to humans from the deadly Ebola virus. Experts say this and other studies show that it is possible to develop a vaccine against such a deadly virus. The scientists will continue to test the vaccine in animals.
They will use increasingly strong amounts of the virus. They want to answer questions about how the experimental vaccine works. And they want to find out more about how the body's defense system might protect against the virus. Scientists also are preparing for small studies in people to test the safety of the vaccine. They hope that future tests will show the vaccine is safe for people. Then the vaccine could be used to protect health care workers and researchers who work with the Ebola virus.
((MUSIC BRIDGE))You are listening to the Special English program SCIENCE IN THE NEWS on VOA. This is Ray Freeman with Bob Doughty in Washington.
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Scientists say kissing may spread a virus thought to cause a cancer linked to the disease AIDS. The virus is called human herpes virus-eight. It is believed to cause a deadly skin cancer called Kaposi's (CAP-oh-seez) sarcoma. The cancer is common among people suffering from AIDS.
Some experts had suspected that the virus that causes Kaposi's sarcoma was passed through sexual activity. But new research has found that the cancer virus may be passed in saliva from deep kissing.
Kaposi's sarcoma are large, cancerous skin tumors that are purple in color. Doctors can usually treat the tumors effectively with a powerful cancer treatment called chemotherapy. But they can be deadly if they spread to other organs.
Kaposi's sarcoma usually affects people with weakened immune systems. It rarely causes sickness among people with normal immune systems. The immune system is the body's defense against disease.Kaposi's sarcoma has been recognized for hundreds of years among people living in southern Europe, the Middle East and Africa. But until recently, scientists in the United States knew little about it. It has only become common in the United States since the discovery of AIDS in the Nineteen-Eighties.
In Nineteen-Ninety-Five, American researchers linked Kaposi's sarcoma to the herpes virus-eight. They found that in the United States, the disease was much more common among men who have sex with other men. And they found that people with several sexual partners were at a greater risk of becoming infected.
For these reasons, scientists suspected that the virus that causes Kaposi's sarcoma passes from one person to another during sex. But in Africa and southern Europe, the virus was found in children as young as six years old. This suggested that the virus could be passed another way.To find out how the disease is spread, scientists tested about fifty homosexual men. They were infected with herpes virus-eight. But they had not developed Kaposi's sarcoma. The scientists took cells from several areas of the body. They found that levels of the virus were highest in cells taken from the mouth.
The results of the study strongly suggest that herpes virus-eight is passed through infected saliva.
The study was done by scientists at the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle, Washington.
((MUSIC BRIDGE))A government laboratory in the American state of Florida is growing an unusual crop -- phorid flies. Scientists plan to release the insects in the southern United States early next year. Phorid flies are fierce enemies of another insect, the fire ant. The scientists want to use the flies as weapons in a campaign to control fire ants.
The new biological control campaign is part of a five-year program. It involves the United States Department of Agriculture and the Florida Department of Agriculture and Consumer Services.
Fire ants are native to South America. They first arrived in the United States in the Nineteen-Thirties. Fire ants are now found on one-hundred-twenty-five million hectares of land in the southern United States.Fire ants cause thousands of millions of dollars in agricultural losses, environmental damage and chemical control costs. The insects attack humans, farm animals, and other animals. They leave small, painful cuts on their victims.
Phorid flies can destroy fire ants. First, a female fly injects an egg into the body of a fire ant. The resulting larva digs into the ant's head. The larva grows and releases enzymes that cause the ant's head to fall off. Inside the head, the larva develops as an adult fly. Phorid flies attack only fire ants. They are not considered dangerous to other ants or animals.Scientists have spent years testing the effectiveness of different phorid flies against fire ants. Three years ago, the Agricultural Research Service released thousands of Brazilian phorid flies in three areas in Florida. The tests proved successful.
The research laboratory in Gainesville, Florida, has been producing about one-thousand five-hundred phorid flies every day. However, that is enough to be released in only two or three areas each month.
Florida state officials offered to help. Their laboratories are expected to increase the production of the insects next year. Scientists will release the phorid flies in eleven southern states, including Florida. Over the next few years, officials will study the flies and their ability to live in areas where they are released. They also will study the spread of the insects to new environments and their effect on fire ant populations.
This SCIENCE IN THE NEWS program was written by Nancy Steinbach, Cynthia Kirk and George Grow. It was produced by George Grow. This is Ray Freeman.And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.