In China
H3N8 pathogen detected in humans for the first time: What you should know about bird flu now
Bird flu mainly affects chickens and turkeys. The bird flu virus can easily spread on poultry farms (symbol image).
© Julian Stratenschulte/ / Picture Alliance
The H3N8 bird flu virus was first detected in a four-year-old boy in China. According to the authorities, further spread is not to be feared.
Since the beginning of the corona pandemic, reports of disease transmission from animals to humans have drawn attention. Concerns about a new pandemic inevitably arise. According to China, it has only recently discovered the first human infection with the H3N8 bird flu virus. Mutations and mixing of bird flu viruses keep creating new subtypes. What does the case in China mean? And how can people be infected with bird flu? The most important questions and answers:
What is known about the case in China?
A four-year-old boy from Henan province has tested positive for the H3N8 bird flu virus after being hospitalized with a fever and other symptoms in early April. The boy’s family raises chickens at home and lives in an area populated by wild ducks. The child got infected directly from the birds, the Chinese National Health Commission said.
The H3N8 virus has been circulating since 2002 and first appeared in North American waterfowl. In 2012, it was also blamed for the deaths of more than 160 seals off the US northeast coast. So far, infections in horses, dogs and seals have been known. Transmission to humans has never been proven.
Can we expect further transmission of H3N8?
No close contact was infected, and according to the National Health Commission, widespread infection from person to person is unlikely. An initial assessment has shown that the H3N8 variant is not yet able to effectively infect humans. According to the authority, the risk of a large-scale epidemic is low. The Health Commission nonetheless urged the public to stay away from dead or sick birds.
What is bird flu exactly?
Influenza viruses circulate in birds worldwide. Bird flu is also known as avian influenza. The infection is caused by different virus strains of the influenza virus type A (e.g. H5N1, H7N1 or H3N8). Turkeys and chickens are particularly affected by the disease. But pheasants, wild birds, guinea fowl, pigeons and waterfowl can also be infected with bird flu. Infected animals suffer from diarrhoea, breathing difficulties and fever.
Veterinarians divide the bird flu viruses into two groups: low pathogenic (low pathogenic) and high pathogenic (high pathogenic) viruses. The Robert Koch Institute (RKI) reports that the highly pathogenic subtypes H5 and H7 of the influenza A virus can, for example, cause major damage to animal populations. This means that if individual animals are infected, almost all birds in the population will fall ill after just a few days and die of bird flu. In such particularly severe cases of bird flu, the term avian influenza is therefore also used.
How is bird flu transmitted to humans?
Transmission from birds to humans probably occurs through inhalation of dust particles containing the virus. Another route of infection is close contact with animals in the absence of hand hygiene. The virus concentration is highest in the faeces of the animals. According to the RKI, people probably have to ingest very large amounts of virus in order to become infected.
What symptoms do infected people get?
The RKI lists the following symptoms as symptoms of bird flu in humans:
- Fever
- Cough
- shortness of breath
- Sore throat
- It can also cause vomiting, diarrhea, and nausea.
- As the disease progresses, pneumonia can develop.
What is the risk of contracting bird flu?
The transmission of avian influenza viruses from animals to humans is not very effective. So they are not very infectious for humans, the RKI informs. However, infected people can develop serious illnesses and even be fatal.
How common is transmission from birds to humans?
“Whenever avian influenza virus is circulating in poultry, there is a risk of sporadic infection and small clusters of human cases due to exposure to infected poultry or contaminated environments. Therefore, sporadic human cases are not unexpected,” writes the World Health Organization (WHO) in its weekly Update on bird flu (as of April 22, 2022). According to this report, since January 2003, a total of 863 cases of avian influenza infection – caused by the H5N1 virus – have been documented worldwide. The infection was fatal in 455 cases. A case of bird flu was recently documented in Colorado, USA. A man under the age of 40 was infected after close contact with infected poultry. The pathogen H5N1 was detected in his nose, he had no symptoms. A case was previously documented in the UK in January. This infection with H5N1 also goes back to close contact with sick birds.
One of the largest avian influenza outbreaks goes back to the pathogen H7N9. In 2016 and 2017, eastern China was particularly affected. 300 people died from infection with H7N9.
China has very large populations of wild birds as well as various farmed birds, an ideal environment for mutation and interbreeding of avian influenza viruses. In China, there are therefore various subtypes of bird flu, with some of the pathogens leading to sporadic infections. This is how it happened in the past that a pathogen was detected in humans. The bird flu pathogen H10N3 was first detected in a 41-year-old from China last year star reported.
Could bird flu be transmitted from person to person?
The RKI informs that there is no evidence of human-to-human transmission worldwide. In a recent study published in the journal Science, scientists at the University of Melbourne are investigating the current wave of bird flu infections. A seriously ill variant of H5N1 has already caused millions of deaths, including among ducks and geese.
The researchers also write there that transmission of bird flu from person to person is largely ruled out. But seriously ill-causing bird flu viruses are a potential pandemic risk. A possible further adaptation of the currently rampant form of the virus could increase its ability for efficient transmission between people, the researchers write. If the virus managed to adapt in this way, it would be practically impossible, as with Corona, to bring the virus under control. The prerequisite for this: the virus would have to adapt in such a way that it could be transmitted from person to person through the air.
Sources:RKI, RKI FAQ, WHO report, Study Science, Lung doctors online, German wave, Colorado Department of Public Health and Environment, UK Health Security Agency