First Human Case of H5N5 Bird Flu Confirmed in the US

Post by : Raina Nasser

Washington, Nov 19, 2025: In a disturbing development, health officials in the United States have confirmed the first human infection of the H5N5 bird flu, a strain predominantly found in avian species. The patient, an elderly individual with pre-existing health issues, was hospitalized in early November after showing signs consistent with avian influenza.

According to the Washington State Department of Health, initial tests identified the virus as Influenza A H5, and subsequent analyses confirmed the rare H5N5 subtype. This incident marks a significant milestone in virology, as it represents the first recorded human case of this strain worldwide, drawing the attention of public health specialists.

Source of Infection
The patient has a mixed flock of backyard poultry exposed to wild birds, health officials reported. Investigators are considering the domestic poultry or contact with wild birds as potential sources of the infection. Authorities are actively observing the situation to clarify how the transmission occurred.

Understanding H5N5 and Bird Flu
Avian influenza, popularly known as bird flu, is caused by Influenza A viruses that circulate mainly among wild aquatic birds. These viruses are categorized based on their hemagglutinin (H) and neuraminidase (N) proteins, leading to various subtypes, including H5N1, H5N8, and the newly identified H5N5.

While some strains cause mild illnesses in birds, highly pathogenic strains can swiftly diminish bird populations. The appearance of H5N5 in humans serves as a reminder of the virus's ability to evolve, highlighting the necessity for ongoing global vigilance.

Transmission and Symptoms
Bird flu viruses transmit through respiratory secretions, feces, or contaminated environments. Human infections generally arise from close, unprotected interactions with infected birds or their droppings.

Symptoms in humans may vary from mild to severe and can include fever, cough, sore throat, shortness of breath, fatigue, muscle aches, vomiting, diarrhea, and conjunctivitis. Severe cases may lead to pneumonia, acute respiratory distress, or death.

Preventive Measures and Global Concern
Health agencies worldwide advise the public to avoid direct contact with sick or deceased birds, utilize protective equipment when handling poultry, and ensure thorough cooking of poultry and eggs. Vigilant surveillance and prompt detection are essential in preventing broader outbreaks and monitoring potential human-to-human transmission.

Chris Green, executive director of the Animal Health and Pandemic Preparedness Alliance, stated: “While the general risk remains low, the occurrence of H5N5 in a human case underscores the persistent threat of zoonotic viruses. Ongoing monitoring and stringent biosecurity measures are vital to preventing further infections.”

The identification of the first human H5N5 case in the US raises ongoing concerns regarding the pandemic capabilities of avian influenza strains. Health authorities globally are reassessing biosecurity measures in poultry farms and live bird markets to ensure rapid response plans are established to mitigate the spread of this unusual yet concerning virus.

As investigations are ongoing, officials stress the importance of public awareness, proper hygiene, and cautious handling of domestic birds as primary defenses against future human infections.