Dolphin in Florida tests positive for avian influenza

In an unexpected and concerning development, researchers recently diagnosed a bottlenose dolphin in Florida with the highly pathogenic avian influenza virus, commonly known as HPAIV.

This diagnosis marks the first documented case of this virus in a cetacean in North America, signaling a significant expansion in the known range of mammals susceptible to avian flu.

Avian influenza in dolphins

The situation was discovered after a marine animal rescue team responded to an emergency involving a dolphin in distress located in Dixie County, Florida. Unfortunately, the dolphin did not survive, and following its death, a comprehensive postmortem examination was performed by researchers to determine the cause.

During the autopsy, scientists took multiple tissue samples from various parts of the dolphin’s body, including the brain, for detailed laboratory analysis. Initially, these samples were analyzed by a local zoological medicine diagnostic lab, which conducted tests to eliminate other possible diseases that might have caused the dolphin’s condition.

After other diseases were ruled out, further tests were conducted at the Bronson Animal Disease Diagnostic Laboratory. It was here that they confirmed the presence of the highly pathogenic avian influenza virus (HPAIV) in the dolphin’s lung and brain tissues, marking a significant finding as it indicated the virus’s ability to infect species beyond birds.

Identifying the invisible enemy

The National Veterinary Services Laboratory provided a detailed classification of the virus identified in the dolphin, specifying that it was the highly pathogenic avian influenza A (H5N1) virus belonging to the HA clade 2.3.4.4b. This particular subtype is notorious for its strong virulence and remarkable ability to cross species barriers, making it a significant concern in terms of animal and potentially human health.

To further investigate this, the virus underwent additional scrutiny at a Biosafety Level 3 enhanced laboratory.

Laboratories of this level are equipped to handle pathogens that can cause serious or potentially lethal disease through inhalation, thus providing a safe and controlled environment for researchers. This setting enabled scientists to conduct more intensive and detailed examinations of the virus’s properties.

In this advanced laboratory setting, researchers were able to perform intricate studies that included genetic sequencing and viral behavior analysis under various conditions. These activities aimed to provide a clearer picture of how the virus infects cells, replicates, and spreads between hosts.

Understanding these aspects is crucial for developing effective control measures and anticipating potential future outbreaks that could affect other species. The work done in this enhanced biosafety environment was key to gaining a deeper understanding of the unique characteristics of the H5N1 virus found in the dolphin.

Unraveling the mystery

Allison Murawski, D.V.M., led the research as part of her involvement with an aquatic animal medicine program and played a crucial role in developing the case report. She worked closely with Dr. Richard Webby, who directs the World Health Organization Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds.

Together, they investigated the origins of the virus, its unique genetic mutations, and its potential to infect other mammals. Their research included sequencing genomes from local birds and analyzing viruses isolated from Northeast seal populations.

Despite their efforts, the experts could not determine the exact source of the dolphin’s infection. “We still don’t know where the dolphin got the virus and more research needs to be done,” Dr. Webby stated.

Research beyond dolphin avian influenza

This case demonstrates the power of collaborative research. Mike Walsh, D.V.M., an associate professor of aquatic animal health and Murawski’s faculty mentor, highlighted the importance of this teamwork.

“This investigation was an important step in understanding this virus and is a great example where happenstance joins with curiosity, having to answer the ‘why’ and then seeing how the multiple groups and expertise took this to a fantastic representation of collaborative excellence,” noted Walsh.

As a result, this research emphasizes the unpredictable nature of influenza viruses and their ability to spread across species. It also underscores the ongoing need for surveillance and research to better understand these pathogens and reduce their impact on wildlife and potentially, human health.

The study is published in the journal Communications Biology.

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