Bird Flu (cont.)

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What are bird flu symptoms and signs?

Most humans get bird flu through close contact with sick or dead poultry or poultry markets in countries (mainly Asia, Europe, the Near East, and Africa) known to harbor the virus. Infected people experience typical flu-like symptoms, including fever, cough, sore throat, and muscle aches. Some people also have nausea, vomiting, diarrhea, or eye infections. Children and even animals (dogs, cats, and other mammals) may develop similar symptoms. Bird flu in humans often can progress to pneumonia and respiratory failure. In fact, bird flu is much more fatal in humans than is normal human influenza. Bird flu causes a very aggressive form of respiratory flu that progress quickly to ARDS (acute respiratory distress syndrome) and a potentially lethal viral pneumonia. More than half (about 60%) of people who have contracted bird flu (H5N1) have died according to the records that have been kept since 1997.

How do physicians diagnosis bird flu?

There is no way to tell what specific strain of influenza a person has without doing tests. In most cases, the diagnosis of flu is determined by the initial symptoms, especially when these occur during the peak flu season (late fall and winter in the U.S.). Sometimes, the doctor may need to perform special tests to be sure the seasonal influenza virus is responsible for the symptoms.

To identify whether an influenza virus is present and to test for the type and strain of influenza, a sample is taken from the back of the throat and/or nose. The doctor uses a cotton-tipped wooden stick and simply rubs the cotton tip at the back of the throat and/or inside the nose. Alternatively, samples may be obtained by rinsing saltwater (saline) solution through the nose and throat and aspirating the fluid back into a specimen jar. The sample is sealed in a packet and sent to the lab for testing. Some offices may use a rapid test that can be done in the office with the result available in 30 minutes. Some rapid tests detect only influenza A virus, while others can detect both influenza A and influenza B virus types. Some cases of flu may be missed by the rapid tests. There are no commercially available tests that specifically detect the individual strains of bird flu.

Again, routine diagnostic tests available in the doctor's office currently cannot determine whether a case of the flu is due to bird flu or human flu. The patient's samples would be sent to a reference laboratory (usually through the health department) for special testing if bird flu is suspected (perhaps because of a known exposure to infected birds). If a patient is in the hospital, the physician may recommend a bronchoscopy, which involves slipping a tube through the mouth into the lungs to aspirate secretions. Most viruses can be identified fairly quickly by polymerase chain reaction (PCR), usually done at the CDC. The CDC can do a procedure known as rRT-PCR (real-time reverse transcriptase polymerase chain reaction) to detect H7N9 and H5N1 viruses. The virus may also be cultivated in tissue culture, and antibodies against it may also be detected in an infected person's serum, but these tests take time. The patient usually has either recovered or died by the time these tests are done.

Medically Reviewed by a Doctor on 1/10/2014


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