Wednesday, August 2, 2007
Researchers from the University of Maryland School of Medicine and the University of Bamako in Mali, Africa, are testing a new vaccine to prevent malaria, which is the leading cause of death in children under the age of 10 in that West African country. The researchers are conducting a clinical trial involving 400 children in Bandiagara, Mali, to assess the vaccine’s ability to prevent malaria disease.
The new vaccine candidate is intended to do this by blocking the replication of parasites in the blood. Small clinical trials already have been conducted to test the vaccine’s safety and ability to trigger antibody responses in adult volunteers at the Walter Reed Army Institute of Research in the United States and in Malian adults and children.
"Malaria kills millions of African babies and children every year and accounts for up to half of all pediatric hospitalizations in many places," says Christopher V. Plowe, M.D, a professor of medicine at the University of Maryland School of Medicine and co-principal investigator on the study. "This parasite has a devastating effect on families all over sub-Saharan Africa – those children who survive still get terribly sick over and over again until they finally develop partial immunity."
Researchers from the University of Maryland School of Medicine’s Center for Vaccine Development and the University of Bamako’s Malaria Research and Training Center have enrolled 400 children between the ages of one and six in the trial, which is being conducted at the Bandiagara Malaria Project in Mali’s Dogon Country. In Mali, malaria transmission season runs from July through December, with transmission and hospitalizations peaking in September and October. About 85 percent of children in Bandiagara have at least one clinical episode of malaria each season; as many as four episodes in a single season have been documented in some children.
Children participating in the study are randomly assigned to one of two groups. The study group is receiving the malaria vaccine, and the control group is getting a licensed vaccine that prevents rabies, which is also prevalent in the area. Both vaccines are given in three doses about 30 days apart. The children are monitored for an hour immediately after receiving each dose and will be followed closely for any side effects, as well as to measure the vaccine’s ability to prevent malaria episodes. At the end of the trial, children who were given the malaria vaccine will be given the rabies vaccine so that all children in the study will benefit from protection against rabies.
"In this trial we are testing a blood stage vaccine, which attempts to block the malaria parasite from getting into the blood cell," says Dr. Plowe. "It doesn’t prevent the infection, but blunts the parasite’s ability to multiply and cause disease. We hope it allows natural immunity to occur during the first five years of life while preventing malaria. If so, we should be able to see a prolonged time before the first documented case of malaria in these children," says Dr. Plowe.
"The Bandiagara Malaria Project is conducting this trial according to the highest international clinical and ethical standards," says Ogobara Doumbo, M.D., professor of parasitology at the University of Bamako and director of the Malaria Research and Training Center. "This is possible only because of long-term commitment by the National Institutes of Health, the University of Maryland School of Medicine and the government of Mali."
The vaccine candidate being evaluated was created by the Walter Reed Army Institute of Research and GlaxoSmithKline Biologicals. The trial is being supported by the National Institutes of Allergy and Infectious Diseases, part of the National Institutes of Health, the U. S. Agency for International Development and the U. S. Military Malaria Vaccine Program.
Mahamadou Thera, M.D., M.P.H., an associate professor of parasitology at the University of Bamako, is the study’s principal investigator.