• Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.
• Most avian influenza viruses do not infect humans; however some, such as A(H5N1) and A(H7N9), have caused serious infections in people.
• Outbreaks of AI in poultry may raise global public health concerns due to their effect on poultry populations, their potential to cause serious disease in people, and their pandemic potential.
• Reports of highly pathogenic AI epidemics in poultry, such as A(H5N1), can seriously impact local and global economies and international trade.

After bird-flu scare in Delhi's zoo and deer park prompted authorities to shut down its premises on 27 Oct., Gwalior Zoo officials in Madhya Pradesh have sent the samples of 15 birds, which died in last three days, for testing for bird flu virus. Earlier in September, India had declared itself free from the highly contagious avian influenza A(H5N1) or bird flu even as it stressed the need for continued surveillance.

The Delhi government has, however, appealed the residents not to touch dead birds and instead call its helpline number if they spot any. While the H5N1 virus can infect people, no human bird flu case has ever been recorded in India despite several outbreaks among birds. Bird flu, also called avian influenza, is a viral infection that can also infect humans and other animals. Most forms of the virus are restricted to birds.

H5N1 is the most common form of bird flu. It’s deadly to birds, and can easily affect humans and other animals that come in contact with a carrier. According to the World Health Organization, H5N1 was first discovered in humans in 1997, and has killed nearly 60 percent of those infected.

Bird Flu Symptoms

Signs and symptoms of bird flu may begin within two to eight days of infection, depending on the type. In most cases, they resemble those of conventional influenza, including:

• Cough
• Fever
• Sore throat
• Muscle aches
• Headache
• Shortness of breath

Some people also experience nausea, vomiting or diarrhea. And in a few cases, a mild eye infection (conjunctivitis) is the only indication of the disease.

How Do Humans Get Bird Flu?

People catch bird flu by close contact with birds or bird droppings. Exactly what "close contact" means differs from culture to culture. Some people have caught H5N1 from cleaning or plucking infected birds. In China, there have been reports of infection via inhalation of aerosolized materials in live bird markets. It's also possible that some people were infected after swimming or bathing in water contaminated with the droppings of infected birds. And some infections have occurred in people who handle fighting cocks. People don't catch the virus from eating fully cooked chicken or eggs.

Prevention

Currently, the best way to prevent infection with avian influenza A viruses is to avoid sources of exposure whenever possible. Most human infections with avian influenza A viruses have occurred following direct close or prolonged contact with sick or dead infected poultry. Infected birds shed avian influenza virus in their saliva, mucous and feces. Human infections with bird flu viruses can happen when enough virus gets into a person's eyes, nose or mouth, or is inhaled. This can happen when virus is in the air (in droplets or possibly dust) and a person breathes it in, or when a person touches something that has virus on it then touches their mouth, eyes or nose. 

Source: healthline.com, webmd.com, mayoclinic.org, WHO, cdc.gov, firstpost.com