Avian influenza

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at January 22, 2016
StartDiseasesAvian influenza

Avian influenza or bird flu is a viral infection. Spread from bird to bird and then from birds to mammals, it is extremely dangerous for humans. Bird flu spreads quickly, infecting all types of fowl and putting humans at risk along the way.

Contents

Definition & Facts

The first human case of bird flu was diagnosed in 1997, and it has so far had a 60% mortality rate. It does not pass easily from human to human, though, making it somewhat less dangerous than more infectious strains of influenza. In fact, the only human to human cases involved extremely close contact, such as a mother giving the illness to her nursing infant.

The main carriers of bird flu seem to be migratory birds, such as wild ducks. However, it can also be spread to domestic fowl, like chicken. This makes the virus more of a concern for people who may work around poultry regularly.

Symptoms & Complaints

There are two different forms of the bird flu: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). Each of these has similar but separate symptoms.

In the case of LPAI, the symptoms can vary, including:

HPAI shares the same symptoms as well as have more severe symptoms:

Causes

Despite there being other strains of bird flu, the common cause of the virus in humans remains the Asian H5N1 strain of avian flu. It was first diagnosed in Hong Kong, and it was linked to handling poultry. Generally, for humans to contract the condition, it must have spread from wild fowl to domestic birds. Then the human must have come into contact with either:

If eggs are cooked to proper temperatures, they do not pose a threat to humans even if they were exposed to avian flu. However, eggs that have been cooked runny could actually transmit the virus. As a result, eggs should be cooked to done and all poultry should be cooked until it reaches an internal temperature of 165 degrees Fahrenheit (73.89 degrees Celsius)

The virus does have a long survival period, being excreted in bird saliva as much as 10 days after diagnosis. If bird excretions are left on surfaces, then they become contaminated as well. It is possible for humans to become ill from touching those contaminated surfaces.

Those at highest risk of contracting bird flu include poultry farmers, travelers, those who eat under cooked eggs and chicken, healthcare workers, and people who live in the same household with someone infected.

Diagnosis & Tests

This viral infection cannot be diagnosed by symptoms alone. Instead, a specialty test has been created by the United States Food and Drug Administration. The test, called A/H5, can check for the Asian lineage strain of the bird flu. It takes about four hours to get the results from the test. The problem is, it is not available at most doctor's offices and hospitals, meaning it may not be an option in every case.

There are other ways physicians can test for avian flu, including performing a white blood cell differential or nasopharyngeal culture to look for the virus. An auscultation may be used to check for abnormal breathing. Additionally, a chest X-ray may be performed as well. If HPAI is suspected, then tests will also be performed to measure function in the heart, kidneys, and liver.

Anyone who visits a doctor with concern of the bird flu can expect a nose or throat swab culture, blood work, and X-rays unless the doctor does happen to have access to the rapid test, which is rare. Results to diagnose the form of influenza usually take about three days to arrive back to the physician.

Treatment & Therapy

There are a few different types of prescription medications used to treat avian influenza once it has been diagnosed in a human. For these medications to work, though, they need to be administered within just hours of the first symptoms appearing. The medications used commonly and recommended by the Centers for Disease Control include:

There have been a few cases of resistant strains that do not react to the medications. As a result, the patient must be closely monitored while taking the prescriptions. If a person has been exposed to the illness but is not yet showing symptoms, a doctor may still prescribe antivirals as a preventative measure.

In most severe cases, to avoid respiratory failure, patients need to be placed on a breathing machine until their body recovers. Some situations actually require a respirator since the patient cannot breathe on their own. Isolation is also required in order to prevent spread of the virus. All patients who have been diagnosed with avian flu will need to be hospitalized to help treat possible pneumonia.

Prevention & Prophylaxis

To prevent the spread of bird flu, it is best to completely avoid any forms of exposure. This includes never handling chickens or other birds, not touching surfaces touched by birds, and cooking eggs thoroughly. Anyone who is required to be around poultry as a part of their job may be prescribed preventative antivirals.

Additionally, and especially when traveling to other countries, it is best to avoid open air markets. These can be easily contaminated by poultry. Finally, anyone who even has the smallest risk of the condition should wash their hands regularly. That's a good practice to help avoid any strain of the flu.