TUESDAY, May 22, 2007 (HealthDay News) -- Scientists are reporting medical advances against malaria, a global scourge that kills more than one million people each year, many of them children.
In one of a number of trials published this week in a special theme issue of the Journal of the American Medical Association, U.S. researchers report that the timely use of key drug combinations saved the lives of children threatened by the mosquito-borne disease.
Over a year and a half, none of the 601 Ugandan children enrolled in the trial died from a recurrence of malaria.
"In the context of sub-Saharan Africa, which has high infant mortality, these children are doing great," said lead researcher Dr. Philip J. Rosenthal, professor of medicine at the University of California, San Francisco.
According to the World Health Organization, malaria remains a leading cause of sickness and death worldwide. More than 3 billion people live in areas at risk of contracting the illness, and more than 500 million people come down with severe malaria each year. The disease is caused by the microscopic Plasmodium parasite, which enters the bloodstream via the bite of a mosquito.
In the trial, Rosenthal's team evaluated the three leading available combination drug regimens for the treatment of P. falciparum malaria, a severe form of the disease with a high death rate. Such evaluations are needed, because there is increasing resistance to some drugs, requiring changes in treatment.
The study included healthy children ages 1 to 10 diagnosed with a first episode of malaria. They were randomized to receive one of three drug combination treatments: amodiaquine plus sulfadoxine-pyrimethamine; amodiaquine plus artesunate; or artemether plus lumefantrine -- two of the newer antimalarial drugs.
There were recurrences of malaria in all three groups, Rosenthal said, with 26.1 percent of children in the first group, 17.4 percent in the second group and 6.7 percent in the third having recurrences in the first four weeks.
But over the next 18 months, there were no deaths or cases of severe malaria, and the incidence of anemia and malaria parasites in the blood was reduced significantly in all three groups, Rosenthal noted.
A key to success was providing good health care for the children in general, not just for malaria, Rosenthal said. "There was free, good health care every time a child got sick," he said. "It shows that providing very good care, with careful attention to each episode of malaria, worked well."
The trial also established "a clear order ranking" of the treatments, with the regimen using the newer drugs working best, Rosenthal said.
The results indicate that "improved malaria management, with evaluation and diagnosis-based treatment for all febrile [feverish] children, is a reasonable goal for Africa," but that continued research about diagnosis, drug delivery and integration of drug treatment with prevention strategies is needed, the report said.
A second trial, conducted in Pakistan, compared two combination treatments using antifolate drugs -- sulfadoxine-pyrimethamine and chlorproguanil-dapsone -- comparing each with a single-drug treatment using chloroquine against P. vivax malaria. This form of the disease causes 70 million to 80 million cases of malaria each year, and accounts for more than 50 percent of malaria cases occurring outside Africa.
The study, which included 767 malaria patients, found that while chloroquine worked best and remains the drug of choice, all three treatments were well-tolerated and cleared the body of malaria-causing parasites within 14 days.
"These drugs may be appropriate for unified treatment where species-specific diagnosis is unavailable, most likely in combination with other drugs," the researchers wrote.
A third paper concentrated on the fight against malaria in the United States. Researchers at the U.S., Centers for Disease Control and Prevention reviewed reports on cases of malaria reported in the United States from 1966 to 2006. That works out to an average of 1,200 cases annually -- almost all imported -- causing up to 13 deaths a year.
The toll could be reduced by obtaining quick travel history after diagnosis, being sure to include malaria as a possible cause of illness, and quick treatment, the report's authors said.
The fight against malaria "has been with mankind forever," added George Dimopoulos, an assistant professor of molecular microbiology and immunology at the Johns Hopkins Bloomberg School of Public Health's Malaria Research Unit.
It is a complex disease, Dimopoulos explained. "The parasite has genetic flexibility that allows it to develop resistance to medication rapidly," he said. "It can also evade the human immune system."
Traditionally, malaria has been a disease of poverty. It was conquered in the United States as living conditions improved.
Research at institutions such as Johns Hopkins looks into every aspect of the malaria parasite's life cycle, including its relationship with the mosquito, Dimopoulos said. "We still don't know everything about its biology," he said.
Tellingly, malaria has never been eradicated from a region unless mosquitoes are first conquered, Dimopoulos said. "But, we need a combined and coordinated effort with multiple approaches," before that battle is won, he said.
Learn all about malaria from the World Health Organization.