Blood Transfusions Probed for Link to West Nile

Federal health officials are investigating whether West Nile virus is transmitted via blood transfusions, citing four cases in which patients were diagnosed within weeks after receiving blood from the general supply.

One of the West Nile patients received blood from three donors whose blood contained genetic evidence of the virus, officials said. All three may have had the infection when they donated.

But the link is far from certain: Blood from donors to a second West Nile patient tested negative for evidence of the virus.

Because all of the transfusion recipients live in areas where the presence of West Nile has been confirmed, authorities said, it is possible that they acquired the disease through mosquito bites, a known route. The recipients live in North Dakota, Louisiana, Mississippi and Georgia.

“We’re very, very concerned,” said Dr. Jesse Goodman, deputy director of the Center for Biologics Evaluation and Research at the U.S. Food and Drug Administration. “We are trying to take some actions to be prepared if this does turn out to be a significant public health issue.”

Government scientists described the latest findings as “fairly surprising” and “unexpected.”

FDA officials said Thursday that they have not yet determined whether they need to take additional steps to safeguard the nation’s blood supply. Those actions ultimately could include testing all donations to detect the presence of West Nile or barring all donations in geographic areas with large numbers of infections.

For now, however, those options aren’t practical. The technology isn’t available for large-scale testing and geographic bans could conceivably do more harm than good to patients in need of transfusions.

Officials emphasized that there is no risk of acquiring West Nile from donating blood.

West Nile, which is harbored by birds and transmitted by mosquitoes, remains a rare illness in the United States. It causes mild symptoms in about one in five people infected. About one in 150 people require hospitalization. West Nile infections can cause meningitis, an irritation of the brain’s membranes, or encephalitis, an inflammation of the brain. The disease can be deadly.

Until more is known, health officials have removed from the shelves any blood products obtained from donors to the four West Nile patients.

Scientists are seeking to determine the status of blood from as many as 100 donors, said Dr. Lyle Petersen, who studies vector-borne infectious diseases at the federal Centers for Disease Control and Prevention. Some donors’ samples may have been used up, however.

Among the three donor samples that tested positive for West Nile, Petersen said, scientists do not know if the virus was alive. Also, it is possible, though unlikely, that the tests yielded false positive results, he said.

With the nation already experiencing a severe blood shortage, some blood banks are worried that any further restrictions on donors will worsen the problem in some regions. The blood banks said they are experiencing a squeeze because of restrictions on donations from European travelers to guard against the human form of Mad Cow disease.

The blood bank officials said they are working closely with federal health agencies to determine whether blood transfusions can pass along West Nile.

“Fortunately, it’s a seasonal virus,” said Dr. Louis Katz, chairman of an American Assn. of Blood Banks panel exploring the topic. “This generally goes away about now. We’re going to have the opportunity over the fall, winter and early spring to gather the information” and decide what to do.

Katz said the chance of West Nile transmission from blood transfusions isn’t a complete surprise because officials have determined that the virus can be transmitted by organ transplantation.

The CDC confirmed Thursday that four patients--not the same as the transfusion recipients--contracted West Nile after receiving organ donations from a Georgia woman infected with the virus. One of those organ recipients died.

Authorities are still investigating whether the organ donor, who was injured in a car accident, contracted West Nile through blood transfusions before she died. That investigation is ongoing; she received blood products from more than 60 donors.

In a recent study, the CDC’s Petersen and other experts estimated that two donors out of 10,000 might show the virus in their blood if they lived in an area with a West Nile outbreak.

Still, Petersen encouraged people not to avoid blood transfusions.

“There is a potential problem,” he said. “But for the average person, if they need a transfusion, the benefits of getting that transfusion are going to far outweigh ... any risk of getting that transfusion, including the risk of getting West Nile virus.”

Meanwhile, this year’s death toll attributed to West Nile rose significantly Thursday, to 54 from 46 a day earlier. So far this year, health officials have received reports of 1,295 human cases of the infection in 30 states and the District of Columbia.

Health officials in Los Angeles County announced Thursday that they had confirmed the first case of West Nile infection in the state--in a young adult woman from the southwestern part of the county. Her case had been considered probable since last week, but a final set of tests conducted at UC Davis verified the diagnosis.

Los Angeles officials said they remain puzzled, though, as to how the woman became infected. She hasn’t left the state, and she doesn’t remember being bitten by a mosquito. Despite increased surveillance, the Los Angeles County West Vector Control District still has not detected any signs of the virus in mosquitoes, dead birds or chicken flocks.

Some health experts have speculated that the woman might have become infected by an errant mosquito that arrived in Los Angeles aboard a plane or truck. But mosquito expert Robert Saviskas called that theory highly unlikely.

“I really don’t think that we’ll know for sure until another two or three weeks go by,” said Saviskas, executive director of the vector control district. “It is possible, although highly unusual, that she’s been infected at such an early stage of the disease that it hasn’t shown up significantly in the other sources.”