Rapid Malarial Diagnostic Identifies Plasmodium Knowlesi

Antibodies that detect Plasmodium falciparum and Plasmodium vivax can also be used to detect Plasmodium knowlesi, generally known as the cause of monkey malaria.

P. knowlesi is being increasingly isolated in humans, and can cause life-threatening infections. A rapid test that could detect and distinguish among the primate malarias is needed for appropriate treatment of patients and epidemiologic monitoring of the prevalence and risk of malaria.

The antigen capture test for human malarias is based on monoclonal antibodies (Mabs) to plasmodium lactate dehydrogenase (pLDH). The four human malarial LDS isoforms were cloned and more than 20 Mabs raised to differentially recognize epitopes among the isotopes.

Dr. Thomas F. McCutchen, from the Laboratory of Malaria and Vector Research of the U.S. National Institute of Allergy and Infectious Diseases (NIAID; Rockville, MD USA) and colleagues used the panel of antibodies and found that those antibodies that detect P. falciparum and P. vivax can also be used to detect P. knowlesi in blood. However, P. knowlesi cannot be distinguished in a mixed infection. In such cases, microscopic examination of the blood would be necessary.

The results of this study appeared in the November 2008 issue of the journal Emerging and Infectious Diseases.

The authors concluded, "An antibody specific for P. Knowlesi would be optimal if the threat of P. Knowlesi increases.” It would involve considerable investment but they claim that according to their findings "only small sequence differences in pLDH isoforms are required to generate antibody panels capable of distinguishing animal pLDH isoforms.”

Related Links:
National Institute of Allergy and Infectious Diseases