Wetland Surveys Reveal Potential Bird Flu Outbreaks

Wetlands are home to a rich diversity of life, but they may also harbor some deadly secrets. Scientists have discovered that some wetlands in the northern US contain bird flu viruses that can survive for months in water and infect birds and other animals.

This could pose a threat to wildlife and human health, especially as climate change and habitat loss alter the wetland ecosystems.

How long can bird flu viruses survive in water?

(Photo : YASSER AL-ZAYYAT/AFP via Getty Images)

Bird flu, or avian influenza, is a viral infection that affects wild and domestic birds. Some strains of bird flu can also infect humans and other animals, posing a potential threat to public health and animal welfare.

But how do these viruses circulate and persist in the environment, especially in wetlands where many waterfowl live and migrate?

A recent study by researchers at the United States Geological Survey (USGS) has shed some light on this question. Using a combination of lab and field experiments, they showed that bird flu viruses shed by wild ducks can remain infectious for more than seven months in surface water of northern US wetlands.

This suggests that these areas could act as environmental reservoirs for the pathogens while birds overwinter in areas further south.

The researchers collected water samples from three wetland complexes in Alaska, Minnesota, and Wisconsin, where they had previously detected bird flu viruses in ducks.

They then tested the samples for the presence and viability of the viruses using molecular and culture methods. They found that bird flu viruses were detectable in 23% of the water samples, and that 25% of those samples contained live viruses that could infect cells in a lab setting.

The longest duration of virus survival was 209 days, which is much longer than previous estimates of a few days to a few weeks.

The study also revealed that the survival of bird flu viruses in water depended on several factors, such as temperature, salinity, pH, and organic matter.

The viruses tended to survive longer in colder, fresher, and more acidic water, and in water with higher levels of dissolved organic carbon.

These conditions are typical of northern wetlands, especially during winter, when the water is frozen and protected from sunlight and microbial degradation.

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Why does it matter for wildlife and human health?

The findings of the study have important implications for understanding the ecology and epidemiology of bird flu viruses. They suggested that wetlands may serve as a source of infection for migratory birds that arrive in spring and summer, potentially exposing them to new or different strains of the viruses.

This could increase the risk of virus evolution and adaptation, as well as the possibility of cross-species transmission to other animals and humans.

The researchers emphasized that the bird flu viruses they detected in wetlands are mostly low pathogenic, meaning that they cause mild or no symptoms in birds and pose a low risk to humans.

However, they also noted that some of these viruses have the potential to become highly pathogenic, or more virulent, through genetic mutations or reassortments.

Therefore, monitoring the presence and diversity of bird flu viruses in wetlands and waterfowl is crucial for early detection and prevention of outbreaks.

The study also highlights the need for more research on the role of the environment in the transmission and persistence of bird flu viruses.

For example, how do different types of wetlands, such as natural or artificial, affect virus survival? How do environmental changes, such as climate change or habitat loss, influence virus dynamics? How do other aquatic organisms, such as fish or insects, interact with the viruses?

These are some of the questions that future studies could address to better understand and manage the risk of bird flu in wetlands and beyond.

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