Reassorted Strain of H5N1 Bird Flu Virus Discovered in Cambodia!

Medical News: Rising Concerns Over New Strain of Avian Flu
In late 2023, scientists in Cambodia uncovered a concerning development: a new strain of H5N1 avian influenza, which appears to have reassorted genes from different strains, marking a significant change in the virus. This discovery has heightened attention on avian influenza (AIV), especially since the virus has shown potential for adapting to mammals, a factor that could increase the risk of it spreading to humans.


Reassorted Strain of H5N1 Bird Flu Virus Discovered in Cambodia

It should be noted that this discovery was kept away from the general public until now with the release of a preprint study of the discovery. This should serve as a wake-up call to the general public that many critical details and also data about the current H5N1 crisis is being concealed or withheld by many governments and health authorities!
 
The Pasteur Institute of Cambodia, along with international partners including the University of Hong Kong, the Francis Crick Institute in the UK, and the U.S. Centers for Disease Control and Prevention, led the research. Their findings have urged global health organizations to stay alert to the evolving threat of this virus and its potential implications.
 
After a quiet decade with no recorded human infections of H5N1, Cambodia began reporting new cases in early 2023, with a total of 16 human infections occurring from February 2023 to August 2024. This Medical News report will discuss the research findings on this new viral reassortant, which combines genetic material from two different H5N1 clades, and why experts believe it may present an increased zoonotic risk. The strain includes genes from the 2.3.2.1c clade that previously circulated in Southeast Asia, along with internal genes from the globally-spreading 2.3.4.4b clade, which has been detected across various continents, even reaching Antarctica.
 
Details of the Cambodian Outbreak and Viral Mutation
In the recent cases in Cambodia, most infected individuals had direct or indirect contact with sick poultry. Although there were no reports of human-to-human transmission, three people succumbed to the infection. The research revealed two phases of spillover into the human population: the first phase in February 2023, driven by the 2.3.2.1c clade, and a second phase beginning in October 2023, involving the novel reassorted strain. This new strain has fully replaced the previous 2.3.2.1c strain in Cambodian poultry, indicating its potential for rapid spread and dominance among avian populations.
 
The study also highlighted the presence of a key mutation, PB2 E627K, in the reassorted virus strain. This mutation has been linked to an increased ability of the virus to infect mammals, as well as improved potential for airborne transmission. Such mutations are especially concerning because they signal an enhanced ability for the virus to cross the species barrier between birds and mammals, a critical factor in the potential zoonotic threat this virus may pose.
 
Increased Surveillance and the One Health Approach
&l t;br /> The research team praised Cambodia's commitment to a "One Health" approach, which combines insights from human, animal, and environmental health fields to combat zoonotic diseases. They emphasized that heightened surveillance is crucial to detect and manage emerging threats early. Additionally, they called for more extensive training for healthcare workers, especially in rural areas where human contact with poultry is frequent. Risk assessment studies are critical in this context, as they could provide insights into how likely the virus is to spread from animals to humans.
 
According to the researchers, Cambodia’s response serves as an example of how coordinated actions among various sectors can enhance readiness and early detection, reducing the potential for human cases. The introduction of the PB2 E627K mutation into poultry populations is a new area of concern, as it indicates the possibility of the virus becoming more widespread in birds and raising the stakes for zoonotic transmission.
 
Reassortment: The Science Behind Viral Changes
Reassortment is a process by which viruses exchange genetic material, creating new combinations of genes that can result in increased adaptability and potential virulence. In the case of this novel H5N1 strain in Cambodia, the virus has gained a unique genetic makeup by combining segments from both the 2.3.2.1c and 2.3.4.4b clades. This specific recombination is particularly troubling because the 2.3.4.4b clade has been known for its ability to infect a wide variety of animal species globally, while the 2.3.2.1c clade has been more localized in Southeast Asia, where it has primarily affected poultry.
 
The genomic analysis shows that the new virus includes the hemagglutinin (HA) and neuraminidase (NA) genes from the 2.3.2.1c clade, along with other essential genes from the 2.3.4.4b clade. The researchers’ detailed genetic sequencing showed that the new strain has now become the primary circulating strain in Cambodian poultry populations. This shift demonstrates how quickly the virus can evolve and spread, leading to potential implications for both avian and human health.
 
Implications for Human Health
The Cambodian outbreak serves as a reminder of the ongoing risks posed by avian influenza viruses, especially those capable of genetic reassortment. The introduction of the PB2 E627K mutation, combined with the reassortment of genes from both clades, has led to a strain with increased mammalian adaptability. Although human-to-human transmission has not been observed, the presence of such mutations raises concerns about the virus’s potential to adapt further and perhaps develop the ability to spread among humans.
 
This reassortment event underscores the need for continued vigilance, especially in regions where people are in close contact with poultry. Surveillance and rapid response capabilities must be strengthened to ensure that new strains are detected early and that containment measures can be quickly implemented. Additionally, the study calls for more resources to support field investigations and laboratory testing to trace and monitor the transmission pathways of these viruses.
 
Conclusions and Future Outlook
The study’s findings underscore the vital role of coordinated health responses and robust surveillance systems in detecting and mitigating zoonotic threats. The novel H5N1 reassortant discovered in Cambodia is a powerful reminder of the challenges presented by avian influenza and the importance of continuous monitoring in high-risk regions. By tracking genetic changes and analyzing transmission patterns, researchers can better understand the potential risks posed by these viruses and implement timely preventive measures.

Moreover, the persistence of H5N1 in avian populations highlights the ongoing need for international collaboration, as viruses respect no borders. For countries like Cambodia, where poultry farming is widespread, public health campaigns aimed at reducing exposure risks in rural areas are crucial. Healthcare workers and local authorities must also be equipped with resources and training to respond quickly to potential outbreaks.
 
The study findings were published on a preprint server and is currently being peer reviewed.
https://www.medrxiv.org/content/10.1101/2024.11.04.24313747v1
 
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https://www.thailandmedical.news/articles/h5n1-avian-flu