First Human Case Of H10N3 Bird Flu Reported In China

Factory farms, where animals are densely packed often in inadequate conditions, significantly increase the risk of disease outbreaks. Image credit: Sodel Vladyslav/Shutterstock.com

The world's first human case of the H10N3 bird flu strain has been reported in China. 

A 41-year-old man living in the city of Zhenjiang in Jiangsu province, northwest of Shanghai, was hospitalized April 28 after first experiencing flu-like symptoms the week before, according to the Chinese National Health Commission on June 01, 2021. 

The patient's condition is stable and he’s ready to be discharged from the hospital. All close contacts of the patient were put under close medical examination, but doctors noticed “no abnormalities”. Fortunately, the risk of a large-scale outbreak is low, Chinese health authorities say. 

“Entire genetic analysis of the virus showed that the H10N3 virus was of avian origin and did not have the ability to effectively infect humans,” the statement reads. 

While this unusual case might not necessarily be much to worry about in terms of global health, the ever-growing risk of emerging flu strains is never too far from humans in the agriculture-intense post-industrial world.

We mainly know flu as the nasty respiratory bug that circulates most winters, but it also has a colossal capacity for causing pandemics. The influenza virus can come in a variety of subtly different forms. There are four types: A, B, C, and D. Human influenza A and B viruses are typically associated with the flu season, while only Influenza A viruses are known to cause flu pandemics.

Influenza A viruses are then split up once more into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). For instance, in this recent case in China — H10N3 — it's an influenza A virus with hemagglutinin subtype 10 and neuraminidase subtype 3. They can then be divided into further clades and subclades. 

Flu pandemics can occur when a new strain of influenza A is transmitted to humans from another animal species, often pigs or poultry that are extensively farmed in close proximity to humans. It's clear that factory farms, where animals are densely packed often in inadequate conditions, significantly increase the risk of disease outbreaks. 

More often than not, there can be an outbreak of, say, bird flu at a poultry farm with no spillover to humans. Even if a spillover to humans does occur, there’s no guarantee the virus will spark a significant outbreak. Sometimes, however, they do cause significant epidemics and pandemics. For instance, different variations of the H1N1 influenza virus have been responsible for the 2009 swine flu pandemic, the 1977 Russian flu outbreak, and the devastating 1918 flu outbreak.

One flu virus that's currently keeping some scientists up at night is a bird flu strain known as H5N8, which has been reported among birds in 46 countries. Most worryingly, there were the first documented human cases reported in Southern Russia earlier this year. 


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