CDC avian flu lab test dubbed quickest yet
new laboratory test that provides preliminary results within four
hours on suspected H5 influenza samples that previous technology
required at least two to three days to produce results.
The speed and efficiency of the test will prove invaluable in detecting the avian flu, which has claimed more than half of the 160 human cases reported in Thailand, China, Vietnam, Cambodia, Indonesia, Turkey and Iraq.
Nearly all of these cases are believed to have been caused by exposure to infected poultry. The concern is that H5N1 will evolve into a virus capable of human-to-human transmission and lead to an influenza pandemic.
The product, Influenza A/H5 (Asian lineage) Virus Real-time RT-PCR Primer and Probe Set, will be distributed to Laboratory Response Network (LRN), a scheme, which designates laboratories increasing laboratory response capacity associated with a potential pandemic.
The testing kits will be distributed by the Centres for Disease Control and Prevention (CDC). The CDC has also shared the test technology with the World Health Organization (WHO) and its collaborating centres around the world.
"This laboratory test is a major step forward in our ability to more quickly detect cases of H5 avian influenza and provides additional safeguards to protect public health," Department of Health and Human Services (HHS) Secretary Mike Leavitt said.
"Thanks to the expeditious and collaborative efforts of CDC and FDA, the availability of this new test gives us one more tool to keep up with the ever changing nature of influenza viruses," he added.
A flu pandemic occurs when a new influenza virus emerges for which people have little or no immunity and for which there is no vaccine.
In an influenza pandemic, the disease spreads easily from person to person in a sustained manner, causes serious illness, and can sweep across the country and around the world in very short time.
"The use of this test by laboratories that are part of the LRN, in conjunction with other laboratory testing and clinical observations, may enable earlier detection of influenza cases caused by this specific virus and allow public health agencies to investigate sources of infection and more quickly respond with control and prevention activities," said CDC Director Julie Gerberding.
Information obtained from this test will be used to track cases of illness with this strain of virus.
Testing for this virus is indicated when a patient has symptoms of severe respiratory illness and a risk of exposure (e.g., direct contact with sick, dead or infected poultry in a country with outbreaks of influenza H5N1 among poultry). If the presence of the H5 strain is identified, then further testing is conducted to identify the specific H5 subtype (e.g., H5N1).
CDC recommends that testing for influenza A/H5 (Asian lineage) should be considered on a case-by-case basis in consultation with local or state health departments. If a clinician suspects a patient may be infected with an avian influenza virus, they should contact their state or local health department.
The H5N1 virus that has caused human illness and death in Asia is resistant to amantadine and rimantadine, two antiviral medications commonly used for influenza.
Two other antiviral medications, oseltamavir and zanamavir, would probably work to treat influenza caused by H5N1 virus, but additional studies still need to be done to demonstrate their effectiveness.
There currently is no commercially available vaccine to protect humans against H5N1 virus that is being seen in Asia and Europe.
However, vaccine development efforts are taking place. Research studies to test a vaccine to protect humans against H5N1 virus began in April 2005, and a series of clinical trials is under way.
