- Bird flu, also known as Avian influenza (AI)
- It is a highly contagious viral disease affecting several species of food-producing birds (chickens, turkeys, quails, guinea fowl, etc.) as well as pet birds and wild birds.
- Occasionally mammals, including humans, may contract avian influenza.
- Influenza viruses are grouped into three types; A, B, and C.
- Only type A is known to infect animals and is zoonotic, meaning it can infect animals and also humans.
- Type B and C mostly infect humans and typically cause mild disease.
- The influenza A virus
- It has two proteins on its surface hemagglutinin (H) and neuraminidase (N).
- Both of which have 18 and 11 different subtypes respectively.
- Leading to different combinations such as H3N2 and H7N9, A(H5N1), and A(H9N2).
- Highly Pathogenic Avian Influenza (HPAI) A(H5N1) virus occurs mainly in birds and is highly contagious among them.
- HPAI Asian H5N1 is especially deadly for poultry.
Effects of flu on Humans
Mostly, humans have only experienced infections by three different H types (H1, H2 and H3), and two different N types (N1 and N2).
Presently, two subtypes, H1N1 and H3N2, circulate among human beings, causing the seasonal flu epidemics.
Since these strains are well adapted to humans, they are referred to as human flu rather than bird flu.
Whenever a new flu A virus establishes itself in humans, it can cause a pandemic, and four such pandemics have occurred since 1918,
1918, the Spanish flu (H1N1)
The 1957-58 Asian flu (H2N2)
The 1968 Hong Kong flu (H3N2)
The 2009 swine flu (caused by a newer version of the H1N1).