- The Washington Times - Monday, August 19, 2002

LONDON British scientists have pioneered a vaccine against malaria that they believe could save millions of lives.
Tests of the vaccination, which employs an innovative approach, have shown that it can produce significant protection against the infection, which is one of the world's biggest killers.
Adrian Hill, a professor from Oxford University's department of medicine who is heading the project, confirmed the breakthrough. He said: "The vaccine is safe, it is working, and we are seeing protection in humans, which is tremendous. We are very encouraged."
The vaccine's target is Plasmodium falciparum, the most dangerous of four types of malaria. The parasite can affect the brain and is responsible for 99 percent of malaria deaths.
The vaccine works by seeking to stimulate a different part of the body's immune system.
Dr. Hill said he and colleagues at Oxford University had conducted safety studies on 170 persons in Britain and Africa. These were so successful that a field trial was begun in Gambia.
Doctors in Gambia working for the malaria unit of the Government's Medical Research Council began giving 360 local persons shots of either the vaccine or dummy injections on Aug. 12. The volunteers will be monitored throughout the country's malaria season, which runs from October to December.
Five hundred million people contract malaria every year and the disease kills 2.7 million. Three-quarters of these victims are younger than 5, making it the biggest infectious killer of children.
The impact on the Third World economy is enormous. Economists calculate that had the disease been cleared from Africa 35 years ago the continent's gross domestic product would be $100 billion greater than today.
So far, the scourge has proved impossible to beat. A postwar plan to kill the Anopheles mosquitoes which carry the organism using DDT ended in environmental disaster, and resistance to anti-malarial drugs is now widespread. Specialists are convinced that malaria will be overcome only when a vaccine is devised that can prevent people from becoming infected in the first place.
This is a difficult task because the parasite's complicated life cycle allows it to evade the human immune system. Within minutes of being released into the bloodstream from an infected mosquito bite, the malaria parasite is safely inside its victim's liver cells.
There it multiplies rapidly before bursting into the bloodstream in huge numbers a week later. Traditional vaccines, which act by producing antibodies that can latch onto foreign bodies in the circulation, have not worked against malaria.
"What is different about our approach is we are trying to stimulate a different arm of the immune system as the parasite lives inside the cells most of the time," Dr. Hill said. "Unless you can catch it on the way in, antibodies won't work against malaria.
"However, it is only when the parasite is released from the liver that people start getting symptoms of malaria, fever, and if they are unlucky, cerebral malaria and death," he added. "If you could get the vaccine to work at the liver stage, even though the liver would get infected, the person would not get ill."
The new approach promotes the production of vital immune cells known as "T cells" in the body, which then destroy malaria-infected cells. The same technique, in theory, also could be used against other forms of malaria.

LOAD COMMENTS ()

 

Click to Read More

Click to Hide