First Severe Bird Flu Case in the US: Is It Time to Worry?
Public apprehension regarding avian influenza heightened this week as the H5N1 virus continued to spread across the nation’s dairy and poultry farms, coinciding with the hospitalization of the first American due to a severe infection.
On Wednesday, federal officials reported that an elderly individual in Louisiana was in a "severe" condition after contracting the virus from a backyard poultry flock.
This individual, whose identity remains undisclosed, is among 61 confirmed cases of infection in the United States this year. Globally, avian influenza has resulted in fatalities for approximately half of those infected; however, the United States has not recorded any deaths and has only seen mild cases until this recent incident.
The Louisiana patient marks the first confirmed case of illness linked to a backyard flock in the U.S. The specific strain of H5N1 that affected this individual differs from the variant that has primarily impacted cattle, poultry, and farmworkers throughout the year, according to the CDC. Nonetheless, it bears similarities to strains found in wild birds and in individuals infected in Washington State and British Columbia.
Key information to consider as the CDC and other federal and state agencies strive to manage the virus includes:
Who is at risk?
Individuals who have close contact with infected animals, such as those working in dairy or poultry sectors, face a heightened risk of contracting avian influenza. Those maintaining backyard flocks or engaging in bird hunting should exercise caution when handling birds, as advised by the CDC. Testing has consistently shown that pasteurized milk and dairy products are safe for consumption. Public health officials caution against the consumption of raw milk, which has occasionally been found to harbor sufficient virus levels to pose a health risk, although no cases of infection through milk consumption have been documented to date.
What are the symptoms?
The majority of individuals infected with avian influenza in the United States have exhibited mild symptoms. According to the Cleveland Clinic, symptoms associated with H5N1 avian flu infection in humans may encompass conjunctivitis, fever, fatigue, cough, muscle pain, sore throat, nausea and vomiting, diarrhea, nasal congestion or discharge, and shortness of breath. Although data remains limited, experts from the College of American Pathologists suggest that farmworkers may have experienced different symptoms compared to others infected, potentially due to variations in the virus strains or differences in exposure routes.
For example, farmworkers might have developed conjunctivitis after touching a contaminated cow and subsequently rubbing their eyes, which is a prevalent symptom among them. In contrast, an individual who encountered a backyard chicken or a wild bird may have inhaled the virus, leading to more severe illness.
A patient in Louisiana, who was exposed through a backyard flock, is currently suffering from severe respiratory symptoms and is in critical condition, as reported by Emma Herrock, communications director for the Louisiana Department of Health. This patient is also noted to have pre-existing medical conditions and is over 65 years of age, which increases the risk of complications from the influenza virus, Herrock stated via email.
Bird Flu Vaccines:
Current Status Health authorities have not yet recommended the use of vaccines for bird flu, as there is currently no evidence of human-to-human transmission, a limited number of infections, and most cases have been mild.
During the winter respiratory virus season, officials have focused on vaccinating the nation’s 200,000 livestock workers against seasonal influenza. Although standard flu vaccines do not protect against H5N1, there is concern that simultaneous infection with both flu strains could result in a more virulent or transmissible variant of bird flu.
In parallel, federal officials have stockpiled approximately 10 million doses of H5N8 vaccine, which they believe may be effective against H5N1 bird flu, in anticipation of a potential escalation in the virus's threat level. In response to fears of an outbreak within its mink industry that could affect workers, Finland provided similar vaccines to its livestock workers this past summer.
The United States has also invested significantly in the research of vaccine candidates for bird flu. A recent study on Moderna’s mRNA vaccine indicated promising results, demonstrating immune responses against the virus in ferrets, a common model for flu vaccine testing. Additionally, researchers at the University of Pennsylvania have created a different experimental mRNA vaccine that successfully prevented severe illness and mortality in infected ferrets.
Efforts are also underway to develop vaccines aimed at protecting animals, particularly valuable dairy cattle. As of Thursday, the virus has affected 875 herds across 16 states, according to data from the U.S. Department of Agriculture. The USDA has authorized seven field safety trials for vaccines in cattle, as reported by Dr. Eric Deeble, a senior official at the agency, although it remains early in the vaccine development timeline.
When should we start to worry?
Upon the initial identification of SARS-CoV-2, testing capabilities were nonexistent. In contrast, Dr. Ben Bradley, an assistant professor in the pathology department at the University of Utah School of Medicine, noted that a test for H5N1 is already available. Dr. Bradley emphasized that the current situation regarding H5N1 presents a markedly different scenario compared to COVID-19, as he articulated during a briefing by the College of American Pathologists (CAP) on Friday.
Nevertheless, he remains vigilant for any warning signs that could suggest the possibility of a larger outbreak. The primary concern would be any instances of transmission occurring between individuals. Additionally, Bradley expressed apprehension that some individuals may have contracted the virus without their knowledge.
Evidence has indicated that certain dairy workers possess antibodies for H5N1, which may imply that the virus is spreading more rapidly and subtly than previously assumed.
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While the CDC has confirmed 61 cases of bird flu in the United States, numerous experts have indicated to Lawyer Monthly that the actual number is likely higher. Bradley, who also serves as the medical director of virology at ARUP, a national testing laboratory, remarked, "The uncertainty surrounding the complete scope of the situation is troubling."
Should the virus continue to infect a greater number of people and animals, it will have increased opportunities to mutate, potentially leading to a strain that is more contagious or hazardous. "We find ourselves in a position where we must remain vigilant regarding the potential threat this poses," Bradley stated. Dr. Donald Karcher, president of CAP and a professor at George Washington University Medical Center, noted that predicting whether bird flu will escalate into a more significant threat is inherently uncertain. "This is a random process that viruses undergo, and it is exceedingly difficult to forecast when such an event may occur," he explained.
The first severe H5N1 bird flu case in the United States underscores the importance of vigilance in monitoring emerging public health threats. While human-to-human transmission remains unconfirmed, the virus's spread among poultry, dairy herds, and wildlife raises concerns about potential mutations that could increase its transmissibility or severity. With effective testing methods, ongoing vaccine research, and public health measures in place, authorities are better equipped to manage this virus compared to previous outbreaks.
However, experts emphasize the need for caution, particularly for those in high-risk professions. Staying informed, following safety guidelines, and supporting prevention efforts are essential to minimizing risks.
