Malaria: a crazy idea that might work

The Bill and Melinda Gates Foundation recently awarded a $1m grant to José A. Stoute, a Pennsylvania state microbiologist, and Carmenza Spadafora, of the Institute for Advanced Scientific Studies in Panama to develop what one of its officials called “a crazy idea that just might work” — treating malaria by microwaving part of the patient, possibly an arm or a leg.

Malaria parasites (Plasmodium spp) convert iron in the red blood cell’s haemoglobin to an inert crystalline pigment, haemozoin, which is then concentrated in the parasite’s vacuole — a space where creatures without a gut store waste products. The researchers, recalling a study which used microwaves to destroy cancer cells tagged with iron, suggested that this iron-rich material could enhance microwave energy absorption so causing the haemozoin to heat up and expand, thus bursting the vacuoles and killing the parasites.

However, there are problems to be overcome before the system can be used on humans. Although the microwave yields less than 1,000th of the power of a kitchen model it has to be fine-tuned to leave healthy red blood cells unharmed. Also, hot spots like those formed in microwaved liquids have to be avoided and patients would probably need repeated treatments because the parasites may hide in organs such as the brain, liver and spleen. “Microwaving the head or abdomen is probably a bad idea,” Dr Stoute said, “but eventually they have to come back out into the blood, and that’s when we’ll get them.”

The researchers believe that a microwave built from commercially available parts and run on solar power would be of huge benefit in the poorer areas of the world. They suggest that bags of donated blood could be treated even where malaria tests are unavailable and one day perhaps microwaves might be installed alongside security scanners at airports to treat travellers as they pass through.