What is bird flu?
Bird flu, also known as avian flu, is an influenza A virus which is spread among birds. Certain strains of this virus can also infect mammals. Of the over dozen strains of bird flu that have been identified, only two strains that can infect humans are currently a cause for concern. However, human infection with bird flu is rare overall. The virus can be spread from birds to humans and a few cases of human-to-human transmission have been reported. Bird flu in humans that is caused by these two strains is fatal in over 50% of people who are infected.
To date there has been less than 500 deaths reported since bird flu is so uncommon. In addition, cases of bird flu may be under reported. Apart from close contact with live birds and bird meat, infection can also occur by eating undercooked poultry or eggs. Bird flu is a naturally occurring infection in some bird species and can be transmitted to domestic birds. There is growing concern about resistance to certain antivirals that is developing in certain strains of the virus and there is fear about a global outbreak.
Types of Bird Flu Viruses
The viruses that cause bird flu belong to the orthomyxovirus family of viruses. These are RNA viruses and there are three strains – influenza A, B or C. Bird flu is caused by influenza A viruses. There are several different serotypes. The viruses are referred to according to its serotype which is determined by the H (hemagglutinin) and N (neuraminidase) proteins of the virus.
The main serotype that was causing bird flu in humans previously was the H5N1 serotype. It caused death in as many as 6 in 10 people who were infected. However, infection with this strain has declined greatly in recent years. As of 2013 the H7N9 serotype has been responsible for most serious bird flu infections in humans. There are other less common serotypes that have also caused human infections but most did not cause severe disease.
Read more on types of flu.
Spread of Bird Flu Virus
Bird flu or avian flu is not a new infection among birds. It is a naturally occurring infection primarily among wild waterfowls. The infection can spread to domestic birds, including chickens, ducks and turkey. Like other influenza viruses, the infection is spread mainly through droplets. This means that secretions such as saliva and mucus may contain the virus and are usually expelled during coughing or sneezing. Even the feces of a bird may carry the virus.
These secretions and feces may then enter through the nose or the mouth with close contact. Although the spread is from bird to human, there have been a few cases where human-to-human transmission has occurred. Overall this spread among people is very rare but there is concern that further mutation of the virus and re-assortment with human influenza viruses could lead to a pandemic similar to the H1N1 ‘swine flu’ outbreak in 2009.
Can bird flu be spread through eating poultry?
Yes. Bird flu can be spread through eating infected poultry, including meat and eggs. However, this is only a problem if the meat and eggs are undercooked. Thoroughly cooking poultry meat and eggs destroys the virus and therefore does not pose a risk to humans who consume it. By cooking poultry meat to temperatures of 74°C (165°F) and higher or eggs are firm is usually sufficient to destroy the virus and prevent any infection.
Is bird flu contagious?
Bird flu is contagious but to varying degrees. It is highly contagious in terms of bird-to-bird transmission. However, the contagiousness is very low when with regards to bird-to-human transmission or human-to-human transmission. This applies to the current strains but in the event of mutation and reassortment of influenza viruses then the contagiousness may change.
Signs and Symptoms
Like the human influenza virus, the bird flu virus mainly targets the respiratory system. However, it tends to affect the lower repiratory tract and lungs to a greater degree than the human influenza virus. Therefore symptoms are more severe and serious complications like pneumonia are more likely to occur.
Read more on chest infection.
The incubation period varies from 2 to 7 days. This means that symptoms arise as early as 2 days after the infection is contracted. However, longer incubation periods even as long as 17 days have been reported. The symptoms of bird flu are largely the same as the human flu but tends to be last longer and be more severe with a high risk of complications.
- Coughing, usually productive and sometimes the sputum is bloody.
- Shortness of breath, often with wheezing and rapid breathing.
- Sore throat, usually accompanied by a hoarse voice.
- Pain in the chest and/or abdomen.
- Fever, temperatures above 38°C.
Other signs and symptoms that may be present include nausea, vomiting and diarrhea. Sometimes conjunctivitis (“pink eye”) may also be present. Brain, heart and kidney disturbances are serious and even potentially life-threatening complications that may also arise. Symptoms of these complications may therefore also be present.
Treatment of Bird Flu
The main treatment option for bird flu is antiviral drugs. Oseltamivir or zanamivir are currently the preferred antivirals for treating bird flu. Other antivirals like amantadine and rimantadine may also be used but there is growing resistance of influenza viruses to these drugs. Certain serotypes of the bird flu virus may also be developing resistance against oseltamivir.
Apart from antiviral medication, supportive measures are usually necessary as is the case with any severe lower respiratory infection. These measures include the administration of oxygen and sometimes even ventilation. Intravenous (IV) fluid administrarion may also be required. Secondary bacterial pneumonia can occur and this may require antibiotics.
Bird Flu Vaccine and Prevention
There is currently no vaccine that is available to the public for the prevention of bird flu. However, a vaccine for one strain of the H5N1 virus has been approved by the Food and Drug Administration (FDA) and is stockpiled in the event of an outbreak. Despite the lack of vaccines against other strains and serotypes, there are several preventative measures that can be helpful for bird flu. This includes:
- Thoroughly washing hands with an antiseptic soap.
- Using an antiseptic hand sanitizer on a regular basis.
- Avoid contact with live birds in high risk areas.
- Beware of cross-contamination of foods during the preparation stage.
- Ensure that poultry meat is thoroughly cooked and do not consume raw eggs.