H5N1 - SCIENCE AND TECHNOLOGY
News:
Mammalian spread of H5N1 and its pandemic potential
What's in the news?
● Peoples
witnessed the seal deaths near the bodies of dead seals on shore of the Caspian
Sea, Dagestan.
● Over
700 dead seals were found along Russia's Caspian Sea coast where the H5N1
variant was earlier detected in wild birds.
Avian Influenza:
● Avian
influenza, or bird flu, is a highly contagious viral infection that primarily affects birds.
Concerns - Spread to mammals:
● Infrequently,
the virus can infect mammals from birds, a phenomenon called spillover, and rarely can spread
between mammals.
● There
are several different subtypes of avian influenza viruses, ranging from low
pathogenic to highly pathogenic types that can cause severe illness and death
in birds.
● H5N1 is a highly
pathogenic subtype of avian influenza that causes severe disease and death in birds.
● H5N1
subtype has caused a number of human infections through close contact with
infected birds, or contaminated environments and is often fatal.
● Recent
reports of H5N1 transmission between mammals therefore raise concerns about its
potential to cause a human pandemic.
Causes of Transmission:
● The
H5N1 subtype has the potential to spill over to other mammals such as foxes, minks, ferrets, seals and domestic cats
when the animals come in contact with infected birds or their feces or consume
carcasses of infected birds and further serve as reservoirs.
● It
is also possible that over time, the virus could evolve through mutations or recombination
with other influenza viruses to adapt to new hosts, leading to further
outbreaks.
Outbreaks in Mammals:
● Recently,
scientists have been investigating a potential mammalian spillover event after
a mass mortality event which killed over 700 seals along Russia’s Caspian Sea coast where a H5N1 variant was detected in
wild birds a few months ago.
Go back to basics:
Bird Flu:
● Bird
flu or avian influenza is a disease caused by avian influenza Type A viruses found naturally in wild
birds worldwide.
Avian Influenza Virus:
● Avian
Influenza type A viruses are classified based on two proteins on their surfaces
– Hemagglutinin (HA) and Neuraminidase (NA).
● There
are about 18 HA subtypes and 11 NA subtypes.
● Several
combinations of these two proteins are possible e.g., H5N1, H7N2, H9N6, H17N10,
etc.
Infected population:
● The
virus can infect domestic poultry
including chickens, ducks, turkeys and there have been reports of H5N1
infection among pigs, cats, and even tigers in Thailand zoos.
Transmission to humans:
● Bird
flu viruses do not normally infect humans. However, sporadic human infections
with bird flu viruses have occurred.
● The
most common route of virus transmission is direct
contact - when a person comes in close contact with infected birds, either
dead or alive.
● Humans
can also be affected if they come in contact with contaminated surfaces or air
near the infected poultry.
● There
is no sufficient evidence suggesting the
spread of the virus through properly cooked meat.
Symptoms:
According
to the US CDC, the reported signs and symptoms of avian influenza A virus
infections in humans have ranged from mild
to severe influenza-like illness.
● Fever,
cough, sore throat, muscle aches, nausea, abdominal pain, diarrhea, vomiting.
● Severe
respiratory illness (e.g., shortness of breath, difficulty breathing,
pneumonia, acute respiratory distress, viral pneumonia, respiratory failure).
● Neurologic
changes (altered mental status, seizures).
Risk groups:
● Children
and adults below 40 were seen to be the most affected and mortality was high in
10-19 years olds.
Impacts of Bird Flu:
● Economic
impact - losses to the poultry industry.
● Threatening
food and vaccine security (due to the use of eggs for vaccine production).
● Raising
animal welfare and environmental concerns
Measures against Bird Flu:
● Revised
Action Plan for Prevention, Control & Containment of Avian Influenza (2021)
● Vaccination
of poultries.
● Opting Culling method.
● Safe
disposal of dead birds.
● Improved
surveillance.
● Cleansing
and disinfecting and reduction of people’s movement.
● Wearing
personal protective equipment when handling birds.
● Vaccination to humans:
Avian Influenza vaccine is available outside India e.g. the USA has developed
the vaccine for Human infection.