Hyderabad: No new cases of the deadly H5N1 human infection have been detected in the world since February 2017, though a few new cases of the virus in birds were detected last week.
Though cases of virus in poultry have dropped significantly, doctors warned that there is no room for complacency.
Over a decade ago, an unprecedented H5N1 pandemic had gripped the world, spreading through Asia, Europe and Africa and devastating flocks and killing several hundred humans. This global spread of the highly pathogenic H5N1 influenza in birds was considered a significant pandemic threat, as outbreaks resulted in millions of poultry infections, several hundred human cases and many human deaths.
While cases of bird flu virus now remain mostly faded from memory, doctors explained why the threat from the virus can still exist.
According to Dr S. Ramakrishna of Amrutha Multispeciality Clinics KPHB & Archana Hospital, Madinaguda, the threat depends on human behaviour and environment. “As with any influenza virus, the bird flu virus is difficult to eradicate as it has the ability to mutate.”
He said the H5N1 virus mutates through its ability for reassortment. Which means the influenza virus can shuffle its genomes (set of genes) and produce new strains.
In the last few years, public health officials have been monitoring two such varieties of bird flu viruses: H7N9 and H5N8.
“The mutation depends on the environment, such as atmospheric temperature and moisture; crowding among infected birds; and the level of contact with humans,” Dr Ramakrishna said. “For example, a virus may develop in a bird in one country but lie latent. But if the bird flies to another country, the virus has the potential to mutate and become more potent due to the environmental factors of the new country. But the presence of the virus should only become a cause for worry if the virus is virulent, and it starts to spread rapidly.”
However, no new report of an H5N1 human infection has been detected since February 2017. According to Dr Manoj Goel, head of pulmonology at Fortis Memorial Research Institute in Gurugram, there may be no future threats to human life either.
“Threats of a bird flu virus in humans have possibly been eradicated,” Dr Goel said. “The epidemic mostly affected poultry like chicken and ducks and wild birds. Humans are principally resistant to bird flu. Human to human contamination is not common. There is a risk of the virus spreading from poultry to humans only if people live close to poultry farms and are in close contact, or by eating infected birds.”
He added, “There is no present resurgence in bird flu but an outbreak in birds has the potential to cause significant damage again. The H5N1 virus has mutated into various other forms. There is no imminent threat to any life form, but since it can mutate and return, there can be no predetermined vaccines for the virus. Vaccines are changed every year according to the mutations of the virus.”
A few new cases of the virus in birds came to light this week. Quick response teams were scrambled to Jharkhand, after over a dozen chicken and a crow were found dead.
While a chicken sample tested positive for bird flu in Godda district, a dead crow in Bokaro was also infected.
The state animal husbandry department on Saturday said samples of dead crows were sent to the National Institute of High Security Animal Diseases in Bhopal.
Confirming that birds had tested positive for the H5N1 virus, Dr Aruna Sharma, assistant commissioner of livestock health in the department of animal husbandry, dairying and fisheries in Delhi, said the situation is under control.
“There were reports of the H5N1 virus in poultry in Jharkhand. We sent a central observer to the place to look observe and contain the virus,” she said. “Post operational surveillance for bird fly is ongoing. We are receiving regular updates from the National Institute of High Security Animal Diseases in Bhopal. There have been no reports of any other positive cases so far.”