While causing fever, chills and possibly even death for its victims, the malaria parasite also leaves a tell-tale sign behind: waste.
"It's the perfect bar code for us to identify it," said Andrew Feldman, a scientist at the Johns Hopkins University Applied Physics Laboratory.
The iron-based waste compound is the key to Feldman and others' efforts to develop a portable machine to detect malaria.
Malaria infects 300 million people a year and causes 1 million deaths, making it the third-deadliest disease in the world after HIV and tuberculosis, according to the World Health Organization. The disease has largely been eradicated in affluent countries by reducing the mosquito population, but continues to ravage poor nations.
The researchers' machine, called a mass spectrometer, has identified malaria in blood during early tests, and scientists believe it could have major effects in poor countries - especially those in Africa, where almost 90 percent of the world's malaria deaths occur.
But now that the scientists are preparing the machine for final testing, they face more difficult questions.
Will U.S. companies be willing to manufacture a machine that costs $25,000 to build and take on malaria, which has largely been eradicated in America?
And, even if they find a willing business partner, will impoverished hospitals be able to afford the machine?
"A lot of places can't even afford a microscope," said Mary Galinski, associate professor at the Emory University School of Medicine and founder of the advocacy group Malaria Foundation International.
The most effective way of testing for the mosquito-borne disease is for a doctor to draw blood and look for parasites under a microscope, a process that can take hours.
Because doctors are scarce in Africa, villagers often have to travel 15 hours to see one. It can take hours to test for malaria, and "you can't keep patients waiting for six hours; they might go home and not come back," said Nirbhay Kumar, professor at the Johns Hopkins Bloomberg School of Public Health.
In many poorer countries, doctors will give patients anti-malarial medicine without thorough diagnosis, which can lead to increased drug resistance. Many forms of malaria are resistant to chloroquine, one of the cheapest and most popular anti-malarial drugs.
APL and Johns Hopkins scientists' mass spectrometer, which measures the weight of molecules, can identify signs of parasites in a fraction of the time it takes humans to pore over slides for them.
"The process could take seconds," Feldman said.
Which means that an entire village could be quickly screened.
"This [machine] could make a huge difference because resistance is a huge problem. And many drugs are toxic, so you don't want to just give them out," said Kumar.
The APL team didn't originally intend to investigate malaria. It was using a mass spectrometer to weigh proteins in October 2001 when it realized the spectrometer could also be used to test for iron.
The team used a kitchen-sized commercial spectrometer in the early stages of its experiments. As it became more confident in its findings, it started using a smaller spectrometer developed by other APL scientists.
Because the machine is small enough to fit into the back of a jeep, "they could transport it to villages and test people there," Feldman said.
Hope for foreign funds
The briefcase-size machine being developed could be too expensive for the Third World, scientists say.
And because the vast majority of malaria cases occur abroad, APL scientists also worry that U.S. companies will be reluctant to manufacture it.
"We just don't hear about malaria here very much," Galinski said. "If people have a choice to put money into their community or into a problem like this, they choose the local issue."
While APL scientists think that foreign companies might be more inclined to fund the project, they also plan on adapting the spectrometer to test for more health problems, including blood in urine and stool. But that will take time.
"There's no doubt we can adapt it to detect blood eventually, but we haven't tested the process yet," Feldman said.
The scientists hope that their machine could be in widespread use in a few years, perhaps with foreign-based backing.
"Maybe there's an Indian company out there that would make it as is," Feldman said.