Health officials are not certain how the donor, a Georgia woman, contracted the virus, but worry she may have become infected through a blood transfusion as doctors worked to save her life. Officials are attempting to locate more than 60 people who donated to the blood stockpile used in the transfusions, hoping to interview and test them for the virus.
Blood from this stock has been given to about a dozen patients; health officials have halted use of any of the blood that has not already been given to recipients.
The three confirmed cases are believed to be the first in which humans contracted the disease without being bitten by an infected mosquito.
One of the four organ recipients, a man who received a kidney, died Aug. 29. Two others developed encephalitis, an inflammation of the brain. The fourth, a 71-year-old Florida woman, has symptoms consistent with those of West Nile virus, but lab results are not yet available.
Although the cases have raised concerns about the safety of the blood supply, doctors say the risk of catching the West Nile Virus through a blood transfusion is slim. Officials say they have not ruled out the possibility that an infected mosquito bit the donor prior to the transfusion — or even bit the recipients individually.
“These patients all lived in areas where mosquito-borne transmission of the West Nile Virus is occurring. It’s important that we not jump to conclusions,” James Hughes, director of the CDC’s National Center for Infectious Diseases, said.
Meanwhile, experts say they’re still unsure whether a human-to-human transmission of the disease could have occurred.
“We don’t even know for sure whether it’s possible to transmit West Nile through transfusion or organ donation,” Dr. Jay Epstein, the U.S. Food and Drug Administration’s top official for regulating blood products, told the Associated Press.
While donated blood is screened for diseases like HIV and hepatitis, the CDC said it would not begin screening all blood and organ donations for the virus.
“There will hopefully be a test someday, but it’s not what we’re working on now,” CDC spokesman Tom Skinner said.
Thirty-two people have died from West Nile virus this year, and more than 670 people have been infected with the disease.