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When is a Fever Caused by Malaria?

By Brian W. Simpson

Through the field site in Macha, Zambia and labs in Baltimore, Johns Hopkins Malaria Research Institute (JHMRI) researchers constantly exchange ideas and scientific studies. Case in point: a new malaria diagnostic tool developed at the School and tested in Macha.

In malarious areas, fevers are routinely blamed on malaria without confirmation through microscopic examination of the patient's blood. But in 40 to 50 percent of cases, the fever's cause is not malaria, says David Sullivan, an assistant professor of Molecular Microbiology and Immunology

"The clinical diagnosis is used a lot because of the lack of resources, but it's often wrong, and you end up overtreating for malaria," says Sullivan. It was common practice when inexpensive chloroquine was still effective, but the new artemisinin-based drugs are much more expensive. Worse still, a snap clinical diagnosis of malaria means precious time is lost if the patient's fever is actually due to pneumonia, bacterial meningitis or other infection.

A microscopic diagnosis (still the diagnostic gold standard despite being developed more than 100 years ago) demands an arduous examination of a blood smear that can take up to 20 minutes. In rural, tropical areas favored by Plasmodium, microscopic confirmation like this is frequently unavailable. So clinicians go with their hunch and see what happens. There had to be a better way.

Sullivan, MD, knew that researchers had found malaria proteins in human urine. So in 2001, he and Peter Scholl, PhD, a senior research associate in Environmental Health Sciences, decided to see if telltale malaria proteins in urine could be used for a quick diagnostic test. A urine dipstick test could be performed like a home pregnancy test—no clinic visit or blood draw necessary—and could provide quick confirmation if a fever's cause is malaria. 

The results of field tests in Macha and lab tests in Baltimore so far are encouraging—the dipstick can detect 1 billionth of a gram of parasite protein in a teaspoon of urine. "It's operable and feasible, but we're now looking to improve it," says Sullivan. "Optimistically, in a year or so, we will be able to roll it out."