The risk to humans from avian influenza remains low - infectious disease expert

Importance of biosecurity highlighted by industry experts
calendar icon 12 December 2022
clock icon 3 minute read

According to a special report by John Edmunds, professor of infectious disease modelling at London School of Hygiene and Tropical Medicine (LSHTM), human health risk due to avian influenza outbreaks remains low.

In his report, Edmunds pointed out how pathogenic and transmissible H5N1 avian influenza is amongst birds. Ongoing outbreaks have led to commercial flock die-offs and strict measures to reduce spread, including culling and the implementation of protection zones around affected premises. Despite these measures, infection continues to spread.

“Indeed, the frequency of outbreaks is increasing, with 126 confirmed cases in England since the start of this October out of a total of 259 cases since the outbreak began in October 2021," Edmunds said. "With each case resulting in the slaughter of affected flocks, millions of birds have been culled so far. The impact on farmers and the poultry industry has been devastating."

At present, though, the risk to humans seems to be very low, Edmunds added. 

“There have only been two documented human infections with this strain of H5N1 – one here in the UK and one in the US," he said. "Crucially, there are no known cases of human-to-human transmission. The virus seems to lack the ability to infect us efficiently. Whilst this is undoubtably good news, there is no room for complacency. Influenza viruses mutate and evolve rapidly and the more this virus spreads the greater the chances that it can acquire the ability to infect humans. This could be as a result of a reassortment event where a person - or perhaps another mammal, such as a pig - is infected by H5N1 and another strain of flu simultaneously."

An event such as this led to the last influenza pandemic in 2009, which Edmunds said highlights the critical need to take precautions. 

"These mostly affect poultry and veterinary workers or those with backyard flocks, but the rest of us should also be mindful of the risks," he said. "Do not touch dead or sick wild birds and report any suspect cases immediately. The risk to humans remains low: prompt and careful action by all of us can help to keep it that way."

Professor Punam Mangtani, Professor of Epidemiology at LSHTM added that it's important to implement good biosecurity measures and avoid coming in contact with sick or dead birds.  

“The importance of good biosecurity and avoidance of contact with sick or dead birds and poultry and live bird markets where there are outbreaks of 'bird flu' is underlined by the findings of LSHTM researchers with public health colleagues at the Institute of Epidemiology, Disease Control and Research, Bangladesh," he said. "Combined vet and medical teams examining crow deaths in 2017 at live bird poultry markets noted workers there were exposed to aerosolised viable avian influenza A viruses."

“Other recent work has also highlighted moderate year round transmission of avian influenza in poultry in live bird markets," he added. "Although there were different timings in peaks of viral activity compared to seasonal influenza in humans, there is still the risk of influenza viral reassortment leading to possible pandemic influenza strains, adding to the evidence supporting the urgent need for large scale improvements in live animal markets."

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