Steve Quayle News Alerts

Sept. 12, 2002

Tests confirm that a Los Angeles area woman was the first person to contract the potentially deadly West Nile virus on the West Coast, health officials said Thursday. Plus, having found that the virus can be spread through organ transplants, the Centers for Disease Control and Prevention has found new evidence that it may also be transmitted through blood transfusions.

THE CALIFORNIA WOMAN, who has fully recovered, had no known exposures to the virus through travel or blood transfusions, so health officials believe she was infected by a mosquito. This means that the virus has completed its journey across the continent.

“However, mosquito surveillance units in Los Angeles and throughout the state have not detected any West Nile virus activity,” Dr. Jonathan Fielding, Los Angeles County’s public health director, said in a statement.

Los Angeles County officials said one other human case of the mosquito-borne virus is suspected, but laboratory results so far have been “indeterminate.”

Meanwhile, officials said all dead birds, mosquitoes and chickens have tested negative for West Nile virus in both Los Angeles County and throughout California. The virus is spread from birds to mosquitoes to humans.

So far no other cases of West Nile have been confirmed west of the Rocky Mountains since the mosquito-borne virus first appeared in the United States in 1999. This year’s outbreak of the disease began in Southern states and has been slowly migrating to the north and west. At least 42 states, now stretching from Maine to California, and the District of Columbia have reported some West Nile activity this year. The virus has also been detected in parts of Canada.

Nationally, the West Nile toll continues to climb, with 1,295 people confirmed with the disease and 54 dead. Those numbers will continue to climb because the disease is now in its peak transmission period, said Dr. Lyle Petersen, deputy director of the CDC’s vector-borne disease division. But cases are expected to drop off as the weather gets colder and disease-carrying mosquitoes disappear.

BLOOD LINK PROBED
Meanwhile, having confirmed that West Nile virus can be spread through organ transplants, federal health officials have found new evidence that it may be transmitted through blood transfusions as well.

The CDC said Thursday that it is investigating five cases of people infected with West Nile who also received blood transfusions. That includes a Georgia woman who died and became an organ donor.

In each case, health officials are tracing donated blood to see if the donors had the virus, too. They said Thursday that one of these patients, a woman in Mississippi, did in fact receive blood from three infected donors.

Still, they said it will be very hard to determine whether this patient — or any patient — got West Nile through the blood, or whether it was transmitted by a mosquito bite.
“There is no single laboratory test that’s going to tell you the person got it from a mosquito bite or from a transfusion,” Petersen said. “So unless something highly unusual happens, like a transfusion recipient in an area where West Nile virus transmission is not occurring, ... it’s going to be very difficult to sort out natural mosquito infection from transfusion infection.”

Officials added that they were testing the blood after it had been processed for transfusion, and it was unclear what effect that may have on the West Nile testing.

Overall, Petersen said, earlier research suggests the chances of a blood transfusion containing the virus is about one in 10,000.

All of the five patients who received blood transfusions lived in areas where West Nile is prevalent, he noted. Two are in Mississippi, one in North Dakota and one in Louisiana, plus the Georgia organ donor. Investigations are under way to see if researchers can prove that blood was the cause of their infection.

Testing is complete on blood donated to one of the patients, and neither of those donors tested positive. Testing is still under way on the three others.

The CDC had already said that four transplant patients who received organs from the infected Georgia donor and then developed West Nile were almost certainly infected by their transplants. On Thursday, they confirmed that this was the route of transmission.

One of these four patients died of West Nile encephalitis, a brain inflammation caused by the virus. The three others are recovering, two after developing encephalitis.

Even if officials conclude that West Nile can be transmitted through blood, there is no blood screening test for the disease available. And health authorities have repeatedly said that the benefits of transfusions for sick people far outweigh the risk of catching West Nile.

Officials emphasized that the risk of becoming ill from a mosquito bite is very low, noting that less than 1 percent of bites from mosquitoes infected with West Nile cause severe disease.

http://www.msnbc.com/news/788671.asp