David Leiby, of the Red Cross, has declared the risk of blood transfusion for Babesia microti to be unacceptably high. Babesia microti is a coinfection of Lyme disease that is transmitted primarily by ticks. Over the past 30 years, between 70-100 cases of transfusion transmitted Babesia have been reported, with at least 12 fatalities. Although the need to screen for the parasite which lives in red blood cells is now recognized as urgent, the method of screening blood has yet to be determined and several obstacles remain before screening practices are adopted. However, according the Leiby, failure to screen is "no longer a viable alternative". The abstract to the article follows the jump. . .

Clinical Microbiology Reviews, January 2011, p. 14-28, Vol. 24, No. 1 American Society for Microbiology. All Rights Reserved.

Abstract: Transfusion-Transmitted Babesia spp.: Bull’s-Eye on Babesia microti by David A. Leiby

Transmissible Diseases Department, American Red Cross Holland Laboratory, Rockville, Maryland 2085

Summary: Babesia spp. are intraerythrocytic protozoan parasites of animals and humans that cause babesiosis, a zoonotic disease transmitted primarily by tick vectors. Although a variety of species or types of Babesia have been described in the literature as causing infection in humans, the rodent parasite Babesiamicroti has emerged as the focal point of human disease, especially in the United States.

Not only has B. microti become established as a public health concern, this agent is increasingly being transmitted by blood transfusion: estimates suggest that between 70 and 100 cases of transfusion-transmittedBabesia (TTB) have occurred over the last 30 years. A recent upsurge in TTB cases attributable to B. microti, coupled with at least 12 fatalities in transfusion recipients diagnosed with babesiosis, has elevated TTB to a key policy issue in transfusion medicine.

Despite clarity on a need to mitigate transmission risk, few options are currentlyavailable to prevent the transmission of B. microti by blood transfusion. Future mitigation efforts may stress serologicalscreening of blood donors in regionalized areas of endemicity, with adjunct nucleic acid testing during the summer months, when acute infections are prevalent. However, several hurdles remain, including the absence of a licensed blood screening assay and a thorough cost-benefit analysis of proposed interventions. Despite current obstacles, continued discussion of TTB without proactive intervention is no longer a viable alternative.

You can follow additional comments on Lyme policy at www.lymepolicywonk.org.  You can contact Lorraine Johnson, JD, MBA at lbjohnson@lymedisease.org.