WNV season reveals rash of polio-like cases/blood screening issues

From: "KD Weber"
WNV season reveals rash of polio-like cases/blood screening issues

West Nile Season Reveals Rash of Polio-Like Cases and Screening Weaknesses
http://ap.tbo.com/ap/breaking/MGA7QBI1ELD.html
By Daniel Yee Associated Press Writer
Published: Oct 4, 2003

BERKELEY, Calif. (AP) - Federal health officials said this year's West Nile
season has revealed weaknesses in a test used to screen the nation's blood
supply for the disease, and that the illness has caused nearly two dozen cases
of paralysis among previously healthy adults.
This year's outbreak of the mosquito-borne illness, which has been particularly
bad in the Great Plains and some Western states, has infected 5,861 people and
killed 115.

Officials of the Centers for Disease Control and Prevention said Thursday that a
screening test used since July cannot detect all donated blood units infected
with the virus.

The government said the test has potentially protected thousands of people,
flagging 617 infected blood donors. But the test, which screens samples in a
pool of multiple blood units, loses its sensitivity in the diluted mix.
"We catch most of the (infected) people, but not all of them," said Dr. Lyle
Petersen, acting director of the CDC's division of vector-borne diseases. The
CDC reported last month that two people had become infected through blood
transfusions.

Testing individual blood units catches more infections but may be too costly,
with an annual cost of $300 million, Petersen said. False positives from
screening individual units of blood may mean the blood industry would have to
throw out "tens of thousands of units of blood that are probably OK," he added.

Meanwhile, nearly two dozen patients in northern Colorado have developed
polio-like paralysis from the virus. Paralysis was first noted as a West Nile
symptom last year, but only a few cases were reported.
"We're recognizing a lot more of these cases - we're kind of surprised to find
this many," Petersen said at the University of California's Berkeley campus.

The paralysis, Petersen said, "looks exactly the same as polio." The CDC is
working to investigate how many more cases of paralysis, which has struck
otherwise healthy adults in their 40s and 50s, have emerged in this year's West
Nile epidemic. Many of those afflicted had to be placed on respirators. Petersen
did not say whether any died.

CDC officials also noted that people with weakened immune systems, such as those
who are taking drugs to suppress the immune system after a kidney transplant,
are up to 10 times more likely to develop severe West Nile symptoms than a
healthy person, Petersen said.

The virus is passed to people by bites of mosquitoes that have fed on infected
birds. Most of the time, the virus causes mild, flu-like symptoms, but in
serious cases, the virus can cause a deadly inflammation of the brain.

CDC officials estimate up to 100,000 people are infected with mild symptoms,
most of which do not result in a doctor's visit. Another 400,000 people are
infected but never show any symptoms.

---

On the Net:

www.cdc.gov

AP-ES-10-04-03 1527EDT

--------------------------------------------------------------------------------