New test spots drug-resistant malaria in travelers

By David Douglas

NEW YORK (Reuters Health) - If travelers become sick after returning from areas in which chloroquine-resistant malaria is endemic, they need to be quickly checked for the disease. A new assay can do just that, Canadian and German researchers report.

"Improved diagnostics are urgently needed to help control the global spread of drug-resistant malaria," Dr. Kevin C. Kain told Reuters Health. "Currently, the detection of malaria depends upon microscopic techniques from the 1800s," which are not reliably accurate, he explained.

Moreover, the old diagnostic procedures "provide no information about what drugs would be most suitable to treat the infection."

Kain, at Toronto General Hospital, and colleagues note in the medical journal Clinical Infectious Diseases that imported drug-resistant malaria is a growing problem in industrialized countries. For the elderly or those who develop severe malaria, the mortality rate can exceed 20 percent.

The researchers developed a real-time assay based on detecting DNA from the malaria parasite known as Plasmodium falciparum, along with the genetic variations that render it resistant to the standard drug, chloroquine.

The assay, Kain said, "is automated, standardized and suitable for use in routine diagnostic laboratories." It gives results in less than an hour.

When the team used the test to screen 200 returning travelers with suspected malaria, they found that 77 patients had chloroquine-resistant P. falciparum infection and 48 had a chloroquine-susceptible strain. Another 35 had other types of malarial infection, while the remaining 40 patients had other causes of fever.

Although the test is relatively expensive, the researchers conclude that "its performance characteristics combined with its rapid results, suggest that it may be a useful diagnostic adjunct in developed countries."

SOURCE: Clinical Infectious Diseases, March 1, 2006.