U.S. Reports First Human Infection of Bird Flu Strain Once Found Only in Animals

A Washington state resident has been hospitalized with H5N5 avian influenza, marking the first time this particular strain has been detected in a human anywhere in the world. The case represents the first reported bird flu infection in a person in the United States in nine months. State and federal health officials are conducting an active investigation to determine the source of exposure and identify any potential contacts.

Patient Profile and Initial Symptoms

The affected individual is an older adult with underlying health conditions who developed influenza symptoms in early November and remains hospitalized. Symptoms included high fever, confusion, and respiratory distress, prompting immediate medical attention. Officials have not released identifying information such as the patient’s name, age, or sex to protect privacy.

The Backyard Connection

The patient maintains a mixed backyard flock of domestic poultry at home that had exposure to wild birds. Health investigators consider the domestic poultry or wild birds the most likely source of virus exposure, though the investigation continues. The exact transmission pathway remains under investigation by state and local public health and agriculture officials.

Understanding H5N5 vs. Other Bird Flu Strains

H5N5 is an avian influenza virus that has previously been reported in animals like ducks, geese, swans, gulls, and terns but never before in humans. This distinguishes it from the more commonly reported H5N1 strain that has caused the majority of recent human infections. Nationally, 71 human cases of H5 bird flu have been documented as part of the ongoing outbreak, with one death reported.

Seasonal Timing and Migration Patterns

The general risk of bird flu increases in late fall and winter as migratory birds travel and come into contact with other animals like backyard flocks. A strain of H5N1 highly pathogenic avian influenza has been circulating in wild birds around the world since it was first detected in the U.S. in January 2022. Wild bird movements create seasonal windows when domestic flocks face heightened exposure risks.

Contact Tracing and Transmission Concerns

Public health officials are contacting anyone who has been in close contact with the patient to monitor for symptoms and provide testing and treatment as needed. This contact tracing serves as a precautionary measure to ensure early detection of any potential spread.

Nevertheless, health officials emphasize that despite this unprecedented detection, the risk to the general public remains low. There has been no known human-to-human transmission of bird flu in the country, and transmission between humans is extremely rare.

The Pandemic Potential Question

Despite the low public risk, experts acknowledge the virus still has ‘pandemic potential,’ though it’s clear the leap from an avian virus to one that spreads efficiently among humans is not easy for this pathogen to make. Scientists describe it as requiring “a little bit of the biologic stars aligning,” with the exact likelihood remaining unknown. Only continued surveillance and time will reveal whether this strain can adapt to sustained human transmission.

Protection Measures for At-Risk Groups

Of the 71 total U.S. cases, 41 occurred in people working with cattle and 24 among poultry workers, demonstrating that close animal contact drives most infections. The CDC recommends that anyone working closely with animals wear appropriate protective equipment and use caution around animal feces.

Washington state has made personal protective equipment including disposable gloves, N95 masks, and eye protection available to commercial facilities upon request.

Safety Guidance for Backyard Flock Owners

The Washington State Department of Health urges people cleaning up around bird feeders and areas exposed to bird feces to wear gloves and disinfect with a mixture of one part bleach to 10 parts water or commercial disinfectant like Lysol spray.

When disposing of dead birds, wear a well-fitting face mask and disposable gloves, use an inside-out plastic bag to pick up the carcass, double-bag it, and dispose in a sealed trash can. Hand washing with soap and water should follow immediately after any contact.

Food Safety and Prevention

People should avoid consuming uncooked, undercooked, or unpasteurized food like raw cheese or raw milk. Raw or unpasteurized milk and dairy products should not be fed to pets either, as cats appear particularly susceptible to severe illness from bird flu infection. Getting a seasonal flu vaccine is especially important for people with exposure to sick birds, as it reduces the risk of simultaneous infection with both human and avian influenza viruses.