US Confirms First Human Infection With H5N5 Bird Flu

The United States has reported the world’s first known human case of the H5N5 strain of avian influenza, raising global public-health attention. The patient, an older adult with pre-existing health issues, was hospitalised in early November after developing symptoms consistent with bird flu. Health authorities confirmed the infection following detailed laboratory analysis.

How The Infection Was Detected

Initial tests identified influenza A H5, and subsequent analysis confirmed the specific subtype as H5N5, a strain previously found only in birds and animals. The patient kept a mixed backyard flock that had potential exposure to wild birds, making animal-to-human transmission the most likely source. Investigators continue to study the exact exposure pathway.

Features Of Avian Influenza

Avian influenza viruses naturally circulate in wild aquatic birds, which act as long-term reservoirs. These viruses can spread to domestic poultry and occasionally to humans. Influenza A strains are categorised using two proteins—hemagglutinin (H) and neuraminidase (N)—leading to various combinations such as H5N1, H5N8, and H5N5. Strains may be low pathogenic, causing mild illness in birds, or highly pathogenic, leading to rapid and widespread mortality.

Why H5N5 Is Under Watch

H5 viruses are known for their genetic diversity and ability to reassort, allowing new variants to emerge. Although the current human health risk remains low, global agencies emphasise continued monitoring. Any strain capable of crossing from birds to humans warrants scientific attention due to possible evolutionary changes within animal populations.

Exam Oriented Facts

• Avian influenza viruses are categorised by H and N surface proteins.
• H5N5 had never been detected in humans before this case.
• Transmission to humans typically occurs via close, unprotected contact with infected birds.
• Wild aquatic birds act as natural reservoirs for Influenza A viruses.

Transmission, Symptoms And Prevention

Bird-to-human transmission occurs through droplets, dust, or contaminated surfaces, particularly in settings such as poultry farms or live bird markets. Common symptoms in humans include fever, cough, sore throat, fatigue, and gastrointestinal disturbances. Severe cases may progress to pneumonia or respiratory distress. Preventive steps include avoiding contact with sick birds, using protective gear when handling poultry, and ensuring thorough cooking of poultry products. Public-health agencies stress surveillance and early detection to curb further spread.