And while this is not yet the time of year to worry about mosquitoes, it seems a good time to take a look at the current policy on screening blood products for WNV, and to ensure that the best policy is in place for the inevitable 2006 season.

WNV can be detected in blood samples by recently developed and approved tests. These tests detect some but not all cases of contamination with the virus. This means that WNV infections that could result from contaminated blood products are potentially avoidable by screening donated blood. However, the majority of WNV infections are asymptomatic, so screening may have a small impact on clinical outcomes. The US Food and Drug Administration (FDA) has mandated screening of donated blood samples. However, the FDA has not prescribed specific screening strategies, and the decision on how to best screen blood samples has been left to the states and the blood collection agencies.

Caroline Korves (of Columbia University) in collaboration with Megan Murray and Sue Goldie (both at Harvard School of Public Health) have done a cost-effectiveness analysis of different screening strategies to see which of them would prevent cases through contaminated blood for a reasonable price. (In an ideal world, cost would not matter when it comes to protecting human life and health, but in reality there is limited money available for public health measures. Studies such as this one are therefore essential to help politicians decide how to spend their budget wisely.)

The analysis, published in the international open-access medical journal PLoS Medicine, revealed that in states with low WNV infection rates, the risk of an infected person donating blood was so low that screening was unlikely to prevent any
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Contact: Paul Ocampo
press@plos.org
415-624-1224
Public Library of Science
23-Jan-2006