Avian Flu: Latest Developments and Should We Be Concerned?

The resurgence of highly pathogenic avian influenza (HPAI), particularly the H5N1 strain, has raised significant concerns globally, not only for animal health but also for its potential impact on humans. Infection prevention personnel are critical in mitigating the risks associated with this evolving virus.

H5N1 has been responsible for substantial outbreaks in wild birds and poultry worldwide, causing mass die-offs and economic repercussions. While avian flu primarily affects birds, there have been isolated human cases, especially in individuals who had direct contact with infected animals. Although the risk of sustained human-to-human transmission remains low, according to the CDC, mutations in the virus could alter its behavior, making it a global health threat.

Recent studies have highlighted that the virus’s ability to infect mammals, including cats, dogs, horses, mink, and seals, indicates its potential to adapt further. This cross-species transmission has emphasized the need for heightened biosecurity measures in both agricultural and health care settings.

Human contraction of H5N1 has been limited but is still concerning. A 13-year-old girl nearly died in British Columbia, Canada, in early November. She has a history of mild asthma and an elevated body-mass index of greater than 35. She presented to the emergency department (ED) with a fever and conjunctivitis. Then, after being discharged, she returned to the ED with vomiting, diarrhea, and respiratory distress.

The letter describing her illness in The New England Journal of Medicine (NEJM) stated that “while receiving bilevel positive airway pressure, to the pediatric intensive care unit at British Columbia Children’s Hospital with respiratory failure, pneumonia in the left lower lobe, acute kidney injury, thrombocytopenia, and leukopenia.” She also received tracheal intubation, venovenous extracorporeal membrane oxygenation, and continuous renal replacement therapy.

According to the CDC, a death occurred, this time in Lousiana, the only one in the US. The Lousiana Department of Health first announced it (LDH). The patient was older than 65 and had comorbidities. The LDH wrote in their press release, “LDH’s extensive public health investigation has identified no additional H5N1 cases nor evidence of person-to-person transmission. This patient remains the only human case of H5N1 in Louisiana.”

Currently, there have been 66 reported human cases in the US, but that could be underreported because of the other strains of flu circulating and could be misdiagnosed, according to Richard J. Webby, PhD, a member of the St. Jude’s Research Hospital Faculty and the director of the World Health Organization (WHO) Collaborating Centre for Studies on the Ecology of Influenza in Animals and Birds.

“From a patient treatment perspective, you don't need to know more than [the patient has a strain of flu] to treat them,” Webby told Infection Control Today. “If it's influenza A or B, they receive the same treatment. So, regarding treatment, it doesn't matter whether it's H1 or H3, so places don't test for that. But yeah, that’s potentially one of the complications with flu season approaching. If H5 started to transmit between people, it would likely take longer to notice during flu season than in the middle of summer. Therefore, many samples are coming in, and testing would have been conducted. But if you detect a flu case in the middle of summer, it will get more attention. You might send it off to a more sophisticated lab for further testing. That makes sense in most cases because, during flu season, you expect to see [the flu].”

Is there a concern that the disease has worsened due to the death in Louisiana? “While the event in Louisiana is tragic, unfortunately, it is not unexpected,” Webby told ICT. “Over the past 25 years of cocirculation, the case fatality rate for H5 infections is over 50%. The fact that infections in the US to date have been mostly mild is more the exception. While the Louisiana case was caused by a slightly different version of the H5 virus than is in cows, I think it’s a little too early to make any conclusions about a possible increase in risk. There is a lot of research [that is] going on to try to answer this question. Right now, there is a lot of H5 virus in wild birds across many parts of the United States, so exposure to the virus is high.”

One concern experts have is that changes in the disease may occur, making it more dangerous for humans. “Highly pathogenic avian influenza A(H5N1) virus infection acquired in North America can cause severe human illness,” the NEJM letter about the patient from British Columbia stated. “Evidence for changes to HA that may increase binding to human airway receptors is worrisome.”

When ICT asked Webby if there was a fear of COVID-19 and avian flu combining into another, deadlier disease, he said, “It’s hard to predict what would happen to someone [with] COVID-19 and avian flu infections simultaneously. The viruses themselves are likely incapable of forming hybrid viruses, but some form of disease exacerbation is possible. During the COVID-19 pandemic, there were some studies of individuals who had COVID-19 and seasonal influenza. Although results varied by studies, overall, there was not much impact.”

Infection preventionists must stay current on the CDC's latest updates and the disease's spread. Some key measures they should take include:

1. Enhanced Surveillance: Monitor cases in humans and animals, particularly in regions with active outbreaks.
2. PPE Compliance: Ensure the appropriate use of personal protective equipment (PPE) for those who may be exposed to potentially infected birds or environments.
3. Hygiene Protocols: Emphasize hand hygiene and decontamination of surfaces in settings where avian flu exposure risk is high.
4. Vaccination Strategies: Advocate for and implement vaccination programs for poultry and encourage seasonal influenza vaccination for workers in at-risk industries to reduce co-infection risks.
5. Education and Training: Equip health care and agricultural personnel with knowledge of avian flu symptoms and transmission pathways to improve early detection and containment.

As H5N1 evolves, infection prevention professionals must remain vigilant, updating protocols to address new challenges and protecting public health against a potentially significant threat.