"This is an amazing success story," says Susan Montgomery, a researcher on the study. "The entire blood community went from the identification of a problem in the blood supply to the development and implementation of a solution nationwide within a year."
In 2002, health authorities confirmed 23 cases of West Nile virus infection associated with blood transfusions. It is estimated that as many as 500 people with high levels of virus in their blood donated blood that year. To reduce the risk of transfusion transmission in the future, blood banks in the United States began screening donations for West Nile virus in July 2003.
Over a six-month period, ranging from late June to December 2003 nearly 6 million blood donations were screened for the virus. Over 1,000 donations from more than 9 states tested positive for the virus and were removed from the blood supply.
"During that period, West Nile virus was the most common pathogen identified in our blood supply," says Montgomery, but she notes it appears to be a seasonal phenomenon that parallels the disease geographically. "The peak numbers occurred in late August to early September. Where we are seeing greater numbers of persons with West Nile disease we are finding more infected donors."