FDA Clears First Test for West Nile Virus
The Food and Drug Administration (FDA) today cleared the first test
for use as an aid in the clinical laboratory diagnosis of West Nile
virus infection. The West Nile Virus IgM Capture ELISA is intended for
use in patients with clinical symptoms consistent with viral
encephalitis/meningitis.
“Emerging infectious diseases such as West Nile virus present a
challenge to the public health community,” said Tommy G. Thompson,
Secretary of Health and Human Services. “When industry and government
collaborate closely to meet a public health need, the resulting new
technology will strengthen our joint efforts to confront diseases
earlier and should lower rates of infection.”
The new test works by detecting the levels of a particular type of
antibody, IgM, to the disease in a
patient’s serum. IgM antibodies can be detected within the first few
days of the onset of illness and can assist in the diagnosis of these
patients.
“ The rapid review and approval of this blood test, which uses
antibody levels to identify persons who were recently exposed to West
Nile virus, reflects FDA’s commitment to making safe and effective
medical products available promptly," said FDA Commissioner Mark B.
McClellan, M.D.,Ph.D. “This test provides a useful tool to combat the
important public health problem of West Nile virus infection, just in
time for the start of the West Nile season.”
The PanBio West Nile IgM assay was evaluated using over 1000 patient
sera, which were tested at four different clinical sites. The test
correctly identified antibody in up to 90 to 99% of West Nile virus
disease cases. Because detection of antibody is not always specific in
patients with acute viral infections, this test is considered
presumptive and should be confirmed by more specific testing.
Although the PanBio test is a valuable aid in the diagnosis of West
Nile virus encephalitis, due to similarities with other viruses in the
same family, there is a need to confirm positive results by an
additional test or by using the current CDC diagnostic guidelines for
diagnosis of this disease.
West Nile virus is a mosquito-borne virus which first appeared in the
United States in 1999. While the virus often presents as a mild
infection that clears without further treatment, some patients develop
severe infection resulting in neurological disease and even death.
The disease is most prevalent during the peak mosquito season which
is expected to begin in July and end in October. Over the past several
years, the geographic range of the virus as well as the number of new
infections has expanded and now covers most of the continental United
States.
Since last September, FDA has also worked very closely with industry
to prepare for this upcoming West Nile virus season and has encouraged
industry to develop blood donor screening tests. In mid June 2003, blood
testing centers began testing the blood supply for West Nile virus,
using experimental test kits that FDA has evaluated and permitted to be
used. FDA also developed guidance to industry recommending procedures to
assess donor suitability and to retrieve and quarantine potentially
contaminated blood products. The investigational screening procedure has
now successfully identified the first human West Nile virus infection in
an asymptomatic blood donor.
Source: FDA News. July 09 2003
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