Avian Influenza (H5N1 Bird Flu)
- Context (TOI): The first US case of H5N1 bird flu (Avian Influenza) in a human was detected in a child in California.
- Also known as bird flu, it is a highly contagious viral infection that primarily affects birds.
- The H5N1 bird flu virus was first detected in 1996 in China (‘H’ and ‘N’ stand for hemagglutinin & neuraminidase, the proteins on the virus’s surface that regulate entry and exit in host cells).
- These viruses (Type A) occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species.
- Migrating waterfowl, most notably wild ducks, are the natural carriers of bird flu viruses.
- Strains of the viruses can generally be classified into two categories:
- Low pathogenicity avian influenza (LPAI) that typically causes little or no clinical signs;
- High pathogenicity avian influenza (HPAI) can cause severe clinical signs and possible high mortality rates.
- Transmission to humans: Most virus strains do not infect humans, but two contagious strains, H7N9 and H5N1, have caused serious medical complications in humans.
- The virus spreads to humans through close contact with live or dead infected birds.
- Human to human spread is rarely reported.
- Symptoms in people can range from mild upper respiratory tract infection (fever and cough) to severe pneumonia, acute respiratory distress syndrome (difficulty breathing), shock, and even death.
