New malaria vaccine shows some promise

0 Comments | Insight on the News, Dec 12, 1994 | by Kirimi Kaberia

A serum that has shown limited success in early testing is boosting optimism in the fight against a disease that has eluded a cure.

Malaria, the mosquito-borne disease that kills millions of people each year, is facing a formidable new foe: a vaccine.

Colombian physician Manuel Patarroyo has developed what could be a breakthrough in tropical medicine: SPF66, a malaria vaccine that researchers have tested on adults in Colombia and the United States, and on children in Tanzania. Other tests are under way in Gambia and Thailand.

While the vaccine holds promise, some medical experts caution that it's not a cure. "Malaria has become worse because the malaria organism has become more resistant to medications," says Lois Olsen, a Kenyan midwife who has studied the disease in Africa. And SPF66 still has "a lot of room for improvement," notes Renato Gusmao, a physician with the World Health Organization. "Its efficacy is about 30 percent. But scientifically speaking, it is a very safe product for human beings."

Early tests indicate that the vaccine induces antibodies against itself but not against the parasite, "which is more important," says Altaf Lal, chief of the molecular vaccine section at the Centers for Disease Control and Prevention in Atlanta. Several antimalaria vaccines are at different stages of development and field testing.

When it comes to malaria, any sign of Progress is cause for hope. The disease annually kills 2 million to 3 million people in the tropics, and a permanent cure has proved elusive. Most people who live in malaria-ridden regions develop an immunity to the disease, but only after suffering multiple infections, and usually over a period of several years.

"Most deaths from malaria occur in children and nonimmune individuals who have recently moved to malaria-endemic regions," notes Lal. In some cases, however, that protective immunity is imperfect: Millions of people who are infected don't get a full-blown case of malaria but do suffer from fevers, low energy and weight loss, among other debilitating symptoms. Complications from malaria also can affect the nervous system, kidneys and lungs. The situation is particularly grave for pregnant women, who can develop anemia and placental infections and pass the disease to their children.

"Pregnant women with malaria get premature babies," says Olsen. "They have a lower proportion of red blood cells, and when the get the malaria parasite, they become anemic because [the parasite] affects their red blood cells."

The World Health Organization, says Lal, is committed to fighting malaria. In the case of SPF66, for instance, "the WHO took a leadership role in moving a product from laboratory to field, which can serve as a model for future vaccine trials.

"There is a sense of optimism that an effective vaccine against malaria may be well within reach," Lal adds.

But in any case, says Olsen, It's better than anything we have had. Although it has a low efficacy, we can at least save a life."