NEW YORK (Reuters Health) Mar 16 - A real-time PCR assay appears to be a swift and effective means of detecting chloroquine-resistant Plasmodium falciparum malaria in travelers returning from areas in which the disease is endemic, Canadian and German researchers report in the March 1st issue of Clinical Infectious Diseases.

"Improved diagnostics are urgently needed to help control the global spread of drug-resistant malaria," senior investigator Dr. Kevin C. Kain told Reuters Health. "Currently the detection of malaria depends upon microscopic techniques from the 1800s, which have significant limitations in both sensitivity -- missing true infections -- and specificity -- false positives -- and provide no information about what drugs would be most suitable to treat the infection."

Dr. Kevin C. Kain of Toronto General Hospital and colleagues note that imported drug-resistant malaria is a growing problem in industrialized countries. Standard laboratory diagnosis can be slow and unreliable and conveys little information about drug resistance. Moreover, the mortality rate can exceed 20% in patients who are elderly or who develop severe malaria.

The researchers therefore developed a real-time PCR assay for P. falciparum and chloroquine-resistance determinants. They used this approach to screen 200 febrile returned travelers. The assay provided results in less than 1 hour.

The performance of this approach was compared with that of the reference standard nested-PCR RFLP assay.

Seventy-seven patients had chloroquine resistant P. falciparum infection and 48 had a chloroquine susceptible strain. Twenty-two were infected with P. vivax. 10 ha P. ovale, and 3 had P. malariae malaria. The remaining 40 patients had other febrile syndromes.

Compared with nested-PCR RFLP, the real-time PCR assay showed a 100% sensitivity and 96.7% specificity for the detection of the chloroquine-resistant K76T mutation.

Although the technique 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."

The assay, Dr. Kain added, "is automated, standardized and suitable for use in routine diagnostic laboratories."