What is bird flu?
Bird flu, also known as avian influenza, is a viral infection that can spread between birds and some mammals. There are many different strains of bird flu virus. Most bird flu viruses only infect birds and do not cause serious disease. However, some strains, such as H5N1 and H7N9, have caused serious outbreaks in domestic poultry and can also infect humans.
When bird flu viruses infect people, they can cause a range of symptoms from mild flu-like illness to severe pneumonia and even death. Since 2003, there have been over 850 confirmed human cases of H5N1 worldwide, with a mortality rate of over 50%. The H7N9 strain has infected over 1,500 people since 2013, with a mortality rate of around 40%.
How do people get infected with bird flu?
Humans can become infected with bird flu viruses through direct or indirect contact with infected birds or contaminated environments.
Direct contact includes:
– Touching, slaughtering, defeathering, or preparing infected poultry for cooking
– Direct contact with surfaces contaminated with secretion or feces from infected birds
Indirect contact includes:
– Contact with surfaces or objects contaminated with bird flu viruses such as cage, feed, water, equipment, and clothing
– Consumption of raw or undercooked poultry products like eggs or meat
– Consumption of unpasteurized poultry products
The virus can enter a human body through the eyes, nose, mouth or throat. It cannot infect humans through properly cooked food.
What are the symptoms of bird flu in humans?
The symptoms of bird flu in humans can vary from mild to severe depending on the strain.
Common symptoms include:
– Fever and chills
– Cough, sore throat and runny nose
– Body aches and headache
– Shortness of breath and breathing difficulties
– Eye infections (conjunctivitis)
– Nausea, vomiting and diarrhea
In severe cases, complications can lead to severe pneumonia, multiple organ failure and even death. Symptoms tend to develop within 3 to 5 days after exposure to the virus.
Who is most at risk of bird flu?
Certain groups of people are at higher risk of bird flu infection:
– People who have direct contact with infected live or dead poultry – especially backyard poultry farmers and slaughterhouse workers
– Health workers caring for infected patients
– Travelers visiting areas with known bird flu outbreaks
– Family members or others in close contact with infected individuals
– People with weakened immune systems or chronic health conditions like diabetes, cancer, kidney disease etc.
In general, bird flu remains rare in humans and sustained human-to-human transmission has not occurred yet. Most human cases are the result of direct poultry contact.
How dangerous is bird flu?
The severity of illness caused by bird flu can range from mild to severe based on the strain:
Bird flu strain | Human cases since 2003 | Deaths | Mortality rate |
---|---|---|---|
H5N1 | Over 850 | Over 450 | Over 50% |
H7N9 | Over 1,500 | Over 600 | Around 40% |
H9N2 | Over 20 | 1 | 5% |
The H5N1 strain, first detected in Hong Kong in 1997, has been the most deadly – with a mortality rate exceeding 50% in confirmed human cases. However, the number of human infections has remained relatively low.
The H7N9 strain emerged in China in 2013 and has infected the largest number of people. While less deadly than H5N1, it can still lead to severe pneumonia.
In general, bird flu remains hard for humans to contract. The rare humans infected tend to be those in close, direct contact with infected birds.
Can bird flu spread between humans?
While certain bird flu viruses like H5N1 and H7N9 can infect humans, they do not spread easily from person-to-person.
Limited, non-sustained human-to-human bird flu transmission has occurred in some clusters – usually involving very close contact between infected patients and family members providing care.
However, so far bird flu viruses have not acquired the ability for sustained transmission between humans, unlike seasonal flu viruses which transmit very easily between people.
The risk is that the virus could eventually mutate and gain the ability of sustained human transmission. This could cause a flu pandemic. Pandemic flu strains in history like the 1918 Spanish flu, 1957 Asian flu and 1968 Hong Kong flu all originated from animal and bird flu viruses.
Is there a vaccine available for bird flu?
There are no vaccines currently available to the public for common bird flu viruses like H5N1 and H7N9.
However, vaccines are being researched and tested:
– An H5N1 vaccine has been stockpiled by the US government for healthcare workers or military personnel if an outbreak occurs. It is not available for the general public.
– Multiple vaccine candidates for H7N9 are under development and testing. China has approved use of an H7N9 for government stockpiles.
– Seasonal flu vaccines do not protect against bird flu strains, but may offer some cross-protection.
Research is ongoing to develop more effective vaccines against a wider range of bird flu viruses that could potentially cause a pandemic.
How can bird flu be prevented and controlled?
Preventing and controlling bird flu relies on early surveillance and containment measures:
– Monitoring and testing wild birds and poultry flocks for infection
– Culling infected poultry flocks
– Restrictions on poultry movement and imports/exports
– Disinfecting affected farms to prevent further spread
– Public awareness campaigns on risks and prevention measures
For individuals, precautions include:
– Avoiding direct contact with wild birds and poultry. Seek medical care if you develop flu symptoms after contact.
– Avoiding travel to affected areas with known outbreaks
– Avoiding consumption of raw or undercooked poultry products
– Washing hands frequently with soap and water after touching birds or eggshells
– Using gloves and face masks when working with birds or poultry
– Seeking medical care promptly if you develop flu-like illness after possible exposure
With proper surveillance, culling, disinfection, and public awareness – outbreaks of bird flu in domestic poultry and humans can be effectively controlled and contained.
Conclusion
Bird flu viruses can occasionally infect and cause illness in humans, especially strains like H5N1 and H7N9. However, sustained human-to-human transmission remains rare.
People at highest risk include poultry farmers, slaughterhouse workers, health workers and those in close contact with infected birds or patients. Proper surveillance, containment measures, personal protective measures and public awareness are key to reduce transmission risks.
While outbreaks in poultry remain a concern, the general public has a low risk of catching bird flu. The viruses have not acquired the ability to transmit easily between humans. Vaccines are being developed but are not yet widely available. With proper precautions, the threat of a human pandemic from strains like H5N1 or H7N9 currently remains low.