How Is Avian Influenza diagnosed?
Central to the problem of dealing with Avian Influenza is the difficulty of diagnosis. A number of upper respiratory infections have similar symptoms — at least at the onset of the illness, including the common cold, seasonal human influenza, and bird flu.
Seasonal flu and bird flu have very similar symptoms — including general malaise
(feeling bad all over), cough, fever, nausea, vomiting, and diarrhea. This is,
needless to say, a huge problem in accurately diagnosing bird flu — and accurate
diagnosis is critical to beginning appropriate treatment as well as initiating
infection control procedures and public health measures.
Currently, accurate testing for bird flu and other vial infections that can cause similar symptoms is difficult and requires specialized testing. This testing is time consuming and only available in specialized reference laboratories, which are few and far between. Fortunately, this may change in the near future.
According to Richard Janeczko, Ph.D., executive vice-president and chief scientific officer, Tm Bioscience, located In Toronto, Canada, is developing an amazing test — not only for bird flu, but for more than fifteen other viral infections including severe acute respiratory syndrome or SARS, many of which can mimic the symptoms of bird flu. (Tm Bioscience is a DNA-based diagnostics company developing a suite of genetic tests. Tm Bioscience’s product pipeline includes tests for genetic disorders, drug metabolism, and infectious diseases.)
The test, called the Multiplexed Respiratory Test, discriminates influenza A from influenza B and identifies the H5-subtype of influenza A (bird flu is “H5N1”) from all other H subtypes. In addition, it can identify almost all the other common, and some uncommon, viruses that cause influenza-like illnesses. This is extremely important in managing patients, communities and economic issues.
Other tests have lower clinical sensitivities and specificities which can
lead to both false positives and false negatives.
By incorrectly identifying an outbreak as due to H5N1, patients could be treated
with anti-virals unnecessarily and so increase the likelihood of speeding the
rise of drug-resistant strains. Also, unneeded vaccination programs in asymptomatic
individuals could be initiated, and damage to local and national economies —
through such measures as culling of commercial poultry operations — could occur.
On the othe hand, a false-negative test result could lead to catastrophic outcomes
including a pandemic.
The test uses swab specimens from the nose and takes less than five hours
from start to finish. It was developed for use as a diagnostic tool and for infection
control in hospitals. The assay has been slated for expedited review by the Food
and Drug Administration (FDA), and TM Bioscience is hoping to have an FDA-cleared
test available by the end of January 2006. If this assay delivers what it claims,
it will have huge applicability on a global basis and save many lives.
Comments (0) 30.07.2009. 12:26
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