This is the VOA Special English DEVELOPMENT REPORT.
Researchers in the United States have discovered that the organism that causes the disease malaria is genetically more developed, and much older, than earlier thought. Because of this, they say it will be harder to develop medicines to prevent and treat the deadly disease.
Plasmodium falciparum (plas-MO-dee-um fall-SIP-ah-rum) is the parasite that causes the most deadly kind of malaria. Each year, the disease kills more than two-million people and infects more than two-hundred-million people. In the past, doctors used the drug chloroquine (KLOR-oh-kwine) to treat malaria. However, over the past few decades the falciparum parasite has developed resistance to the medicine.
This resistance to chloroquine was first discovered in parts of South America and Southeast Asia in the nineteen-fifties. Health experts believed resistance to the drug then spread to other parts of the world. However, a new study by scientists at the National Institutes of Health near Washington, D-C, disputes this idea.
The researchers studied the genetic structures of eighty-seven falciparum parasites collected from around the world. They learned that the parasites had been developing resistance to chloroquine independently in two areas in South America, one area in Papua New Guinea and one area in Southeast Asia.
In a second study, the scientists examined more than two-hundred genes from five falciparum parasites. The parasites were collected in South Asia, Africa, South America, Central America and Papua New Guinea. The researchers discovered several genetic differences among the parasites. They also learned that the parasites have been developing separately for at least one-hundred-thousand years.
For several years, scientists have debated when malaria first developed. A few years ago, a genetic study of falciparum parasites found the disease to be between three-thousand and five-thousand years old. The study also found the parasites to be genetically similar. This latest research disputes those results.
Xin-zhuan Su (sin-schwan soo) led the two studies published last month in the publication Nature. He says that new treatments to fight malaria may be possible as scientists learn more about the history of the falciparum parasite.
This VOA Special English DEVELOPMENT REPORT was written by Jill Moss.