(April 23, 2008 - Insidermedicine) Pyruvate kinase deficiency, an inherited autosomal recessive trait in humans that causes nonspherocytic anemia, confers protection against malaria, according to research published in the New England Journal of Medicine.

Here are some recommendations for helping travelers avoid contracting malaria, from the Infectious Diseases Society of America:

•    Practice the following measures to prevent mosquito bites: protective clothing to cover exposed skin, application of repellents, and sleeping in areas protected by netting and screens.

•    Currently, repellents that contain 20% to 50% DEET are considered to provide sufficient protection.

•    Select chemoprophylaxis following a careful assessment of malaria risk during the trip and whether the traveler has contraindications to a particular antimalarial.

Researchers from the McLaughlin–Rotman Centre for Global Health in Toronto infected the erythrocytes of three individuals homozygous for pyruvate kinase deficiency resulting in nonspherocytic anemia as well as two heterozygous carriers of the condition with two different isolates of plasmodium falciparum, the organism responsible for malaria. They compared the outcomes with similar testing using the erythrocytes of healthy controls.

Invasion of plasmodium falciparum into erythrocytes was reduced in patients homozygous for pyruvate kinase deficiency but not in those heterozygous for the condition or in healthy controls. This phenomenon appeared to be due to structural differences in the erythrocytes of those with homozygous mutations. Phagocyte uptake and macrophage clearance of infected erythrocytes was also elevated among those with pyruvate kinase deficiency as well as in heterozygous carriers, but not healthy controls.

We had a chance to speak with Dr. Kevin Kain, a Professor of Medicine at the University of Toronto, and the director of the McLaughlin–Rotman Centre for Global Health, who gave us some further insight into the results of this study.

While those with symptomatic nonspherocytic anemia are probably too ill to benefit from this mutation, on balance, heterozygous carriers of the condition show no anemia symptoms while still enjoying some protection from malaria.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.