2021 brought with itself the news of thousands of birds falling prey to bird flu across 7 states of India. Since bird flu cases in humans have been seen in India previously, should you be concerned now? Let’s understand what bird flu is and what steps will help you prevent it.
Bird flu
Also known as avian flu, it is the disease caused in birds due to influenza A viruses, such as A (H7N9), A (H5N8), and the most common one — A(H5N1). These viruses generally infect only birds but can jump onto other animals and humans too. Wild birds are the natural carriers of these viruses. Depending upon the virus strain’s ability to cause disease, birds may either develop severe disease or not develop any sickness at all.[1]
Its spread in birds
Bird flu can spread to healthy and domestic birds when the infected wild birds migrate to other places and shed the virus through their stools, nasal secretions, saliva, etc. On coming in direct contact with these or with infected surfaces/environments, healthy birds develop serious infections, which can eventually kill them.[2]
Bird flu in humans – The major concern
Bird flu viruses don’t normally infect humans, but if they do, the person may develop severe disease, having a high mortality rate of 60% [3]. The risk of bird flu is higher in people who work with poultry birds or live in areas where humans and domestic birds reside closely together. H5N1 bird flu does not spread easily from person to person. The very few cases of human-to-human transmission have been among people with exceptionally close contact. The major reasons because of which humans can get infected are if they come in close contact with [3]:
– Infected live or dead birds
– Feces of infected birds
– Surfaces or environments contaminated by the infected birds
– Infected birds during slaughter or defeathering
Why should humans be cautious?
Cases of bird flu in humans are rare but not impossible. It is extremely important to take precautions because every time the virus infects a human, it gets the opportunity to enhance its ability to infect more humans and developing into a strain of pandemic.[4]
Other than this, no one can predict how fatal a virus will be for two different species. For e.g. the A (H7N9) virus which caused the 2013 bird flu pandemic, showed no symptoms in birds, whereas when it jumped to humans it caused severe disease that often proved fatal.[1]
Signs of bird flu in humans
When bird flu sets in, it may cause abdominal pain, chest pain, and diarrhea. Gradually with time, it may develop into severe respiratory illness, causing [3]:
– Fever (often high fever, > 38°C)
– Malaise
– Cough
– Sore throat
– Muscle aches
– Pneumonia
– Neurologic changes, rarely (such as altered mental state or seizures)
Treating bird flu
H5N1 infection in humans is most likely to cause severe disease, requiring immediate hospitalization and intensive care. However, several antiviral drugs such as oseltamivir, peramivir, and zanamivir have been found helpful in deterring fatality and increasing the chances of recovery. [5]
Is there a vaccine for H5N1 virus or bird flu?
Vaccines have been developed for the prevention of H5N1 influenza as a step towards pandemic preparedness. This inactivated influenza virus vaccine is for use in people 18 through 64 years of age who are at increased risk of exposure to the H5N1 influenza virus subtype contained in the vaccine. It will be available for use if the H5N1 virus develops the ability to spread from person to person, leading to a pandemic. Hence, it is not available for widespread use now. However, the roll-out will be done only after checking the several factors that affect the effectiveness of the vaccines. [4]
Bird flu won’t spread to you if you
– Cook the meat and eggs at least for half an hour at temperatures of 700C or more [6].
– Ensure that eggs are not runny and well-cooked.
– Avoid close contact with infected or suspected birds and animals, especially their droppings, saliva and other secretions [6].
– Keep raw meat and items that are eaten raw separate [6].
– Remember to wash your hands thoroughly with soap and water frequently, especially after handling poultry and eggs [6].
– Refrain from visiting live bird markets and similar places with large concentrations of birds, especially in affected areas.
(The article is reviewed by Dr. Varun Gupta, MBBS, MD (Pharmacology))
References
1. Questions and answers on avian influenza. European Centre for Disease Prevention and Control. https://www.ecdc.europa.eu/en/zoonotic-influenza/facts/faq-avian-influenza
2. Avian influenza: Frequently Asked Questions. All India Institute of Medical Sciences (AIIMS). https://www.aiims.edu/aiims/bird-flu/FAQ_Bird_flu.htm
3. FAQs: H5N1 influenza. World Health Organization. https://www.who.int/influenza/human_animal_interface/avian_influenza/h5n1_research/faqs/en/#:~:text=H5N1%20is%20a%20type%20of,infection%20from%20person%20to%20person
4. H5N1 Influenza Virus Vaccine, manufactured by Sanofi Pasteur, Inc. Questions and Answers. US Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/vaccines/h5n1-influenza-virus-vaccine-manufactured-sanofi-pasteur-inc-questions-and-answers
5. Avian Influenza A Virus Infections in Humans. Centers for Disease Control and Prevention. https://www.cdc.gov/flu/avianflu/avian-in-humans.htm
6. Bird Flu. All India Institute of Medical Sciences (AIIMS). https://www.aiims.edu/aiims/bird-flu/bird-flu-management.pdf