Human spillovers of bird flu rare but also lethal, says scientist

While human cases of bird flu are still rare, a 11-year-old Cambodian girl died after contracting the virus, WHO also confirmed a human case of bird flu in a Chinese woman

New Delhi:  Human infections of bird flu are generally rare but when the spillover happens, it has a high mortality rate of around 50 per cent, said Vinod Scaria, a biologist, on Wednesday.

The latest outbreak of avian influenza A (H5N1) virus has killed a record number of birds and also spread to otters, sea lions, foxes, dolphins and seals, among others.

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Speaking to IANS, Scaria said that the present H5N1 outbreak is largely caused by the 2.3.4.4b lineage of the virus and is probably one of the largest in recent history.

“In short, typically mammalian spillovers of avian Influenza are rare and typically also lethal,” said Vinod, a scientist at CSIR-Institute of Genomics and Integrative Biology (IGIB).

“Since the numbers are large, this provides a unique opportunity for the virus to mutate and adapt to the mammalian host.

“Apart from affecting the poultry industry, the biggest risk is extinction of possibly a number of birds which were already at the edge of extinction,” he told IANS.

While human cases are still very rare, an 11-year-old girl in Cambodia died after contracting the avian influenza A (H5N1) virus. The World Health Organization (WHO) also confirmed a human case of bird flu in a Chinese woman.

While the risk of “human-to-human spread is low” … “further human cases can be expected”, till the time avian influenza viruses are circulating in poultry, the global health body said.

“Human infections are typically rare but when they happen, comes with a high rate of mortality, around 50 per cent,” Scaria said.

“Handling infected birds with adequate precautions would go a big way in minimising human infections,” he advised.

Meanwhile, a number of pharma companies including Moderna, Sanofi and GSK are preparing to develop a vaccine against bird flu, in case it gets spilled over to humans, according to media reports.

Moderna announced successful Phase 1 clinical trial results this week for this flu-fighting mRNA-1440. The vaccine is intended to combat Influenza Virus H10N8, a strain of bird flu which began commonly appearing in 2014.

GSK, and CSL Seqirus are developing or are about to test sample human shots. Sanofi is also ready to start producing the jabs if needed, with the help of existing H5N1 vaccine strains that they have in stock, media reports said.

According to the WHO, from 2003 to 2023, a total of 873 human cases of infection with influenza A (H5N1) and 458 deaths have been reported globally from 21 countries.

The WHO has said that available epidemiological and virological evidence suggest that current bird flu viruses have not acquired the ability of sustained transmission among humans.

The agency also advised regular hand washing and good food safety and food hygiene practices. It also stressed the importance of global surveillance to detect and monitor virological, epidemiological, and clinical changes associated with emerging or circulating influenza viruses that may affect human (or animal) health and timely virus sharing for risk assessment.