Rising Mammal Infections Pose Concern for Potential H5N1 Pandemic

A recent review published in the journal Emerging Infectious Diseases has shed light on the alarming increase in mammalian avian influenza A (H5N1) infections. The study analyzed literature from the past two decades, focusing on two panzootic periods – 2003 to 2019 and the ongoing 2020 to 2023 period. The findings indicate a rise in mammal-to-mammal transmissions of H5N1, highlighting the need for continuous surveillance to prevent a potential global pandemic.

Avian Influenza Spreading to Mammals:

Highly Pathogenic Avian Influenza (HPAI) caused by subtypes (H5 and H7) of type A viruses has been a significant concern, primarily affecting avian species. However, since 2003, HPAI A (H5N1) has been observed to cross species barriers and infect mammals, leading to two unprecedented panzootic events. These events have raised alarm within the scientific community due to the potential for human transmission, economic losses, and the impact on endangered wildlife.

Overview of the Study:

The review compiled and analyzed scientific literature on natural mammalian H5N1 infections, including humans, comparing data from previous panzootics to the ongoing one. The study focused on infected species, their habitats, infection sources, and viral mutations enabling cross-species transmission. Data from various sources, including online databases and government reports, were collected for analysis.

Key Findings:

  1. The ongoing panzootic has spread to 26 countries across four continents, including Asia, Europe, South America, and North America, surpassing previous panzootics in terms of geographic coverage.
  2. The current panzootic has already infected over 48 mammalian species, including marine mammals, posing a significant threat to biodiversity.
  3. H5N1 strains with novel mutations allowing mammal-to-mammal transmission have been identified, raising concerns about the potential for a global pandemic.
  4. Close contact with infected birds or carrion remains the primary source of infection for most mammals.
  5. While human-to-human transmission has not been reported, the risk of a pandemic remains low but should be closely monitored.

Implications for Human Health:

The rise in mammalian infections with H5N1 is a cause for concern, as it increases the risk of human transmission. Governments and health organizations need to prioritize surveillance and prevention efforts to avoid a potential global pandemic. Learning from past pandemics, such as the Spanish influenza, it is crucial to take proactive measures to protect both biodiversity and human health.

Urgent Need for Surveillance and Prevention:

Continuous surveillance of H5N1 infections in both avian and mammalian populations is essential to identify and monitor any emerging strains with increased transmissibility. Strict biosecurity measures in poultry farming and responsible wildlife interactions are necessary to mitigate the risk of viral spillover. Governments must prioritize efforts to protect biodiversity and human health by reassessing current food production practices and minimizing the risk of zoonotic diseases.


  1. What is H5N1 avian influenza? H5N1 avian influenza is a highly pathogenic viral disease caused by subtype H5N1 of the influenza A virus. It primarily affects avian species but can also infect mammals, including humans.
  2. How has H5N1 spread to mammals? While the primary source of viral transmission remains contact with infected birds, there has been a rise in mammal-to-mammal transmissions. This indicates that H5N1 strains are evolving and increasing their ability to infect different species.
  3. What are the potential risks of mammal-to-mammal transmission of H5N1? Mammal-to-mammal transmission of H5N1 strains could lead to a global pandemic, causing unprecedented biodiversity loss and economic damage. It poses a significant risk to both wildlife and human health.
  4. Has human-to-human transmission of H5N1 been reported? Currently, there is no evidence of human-to-human transmission. However, the possibility cannot be ruled out, as history has shown that avian influenza viruses can adapt to infect humans, as seen in the Spanish influenza pandemic.
  5. What measures can be taken to prevent a potential H5N1 pandemic? Continuous surveillance, strict biosecurity measures in poultry farming, responsible wildlife interactions, and proactive efforts to identify and monitor emerging strains are crucial in preventing a potential H5N1 pandemic. Governments need to prioritize these measures to protect biodiversity and human health.


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