Avian Influenza Landscape in the US

TOPLINE:

An analysis of individuals with laboratory-confirmed highly pathogenic A(H5N1) virus infections in the United States reveals conjunctivitis as the primary symptom affecting those exposed to animals, with most cases being generally mild. 

METHODOLOGY:

• Researchers analyzed data of 46 patients (median age, 34 years; 80% men) with laboratory-confirmed A(H5N1) virus infections collected through surveillance monitoring from March 28 to October 31, 2024, in the United States.
• A nasopharyngeal swab, a combined nasal-oropharyngeal swab, or both and a conjunctival swab were collected from occupationally exposed individuals after 10 days of exposure.
• Presumptive positive samples were confirmed through molecular detection, and cases were interviewed for sources of exposure, symptoms, treatment and safety measures followed.

TAKEAWAY:

• Overall, 25 patients (median age, 39 years; 100% men) were exposed to infected cows and 20 (median age, 28 years; 55% men) were exposed to infected poultry; one patient had unidentified exposure.
• The most common symptom was conjunctivitis (93%), followed by fever (49%) and respiratory symptoms (36%).
• A higher proportion of poultry workers had fever, headache, myalgia, and respiratory symptoms than dairy workers, whereas conjunctivitis alone was most common among dairy workers.
• The majority of patients received oseltamivir (87%), with a median treatment duration of 5 days.

IN PRACTICE:

“Although the risk of the A(H5N1) virus to the US public is currently low, good farm biosecurity is paramount and requires strong coordination between public health and animal sectors through a collaborative One Health approach, which is multisectoral and recognizes that the health of people, animals, plants, and the environment are closely linked and interdependent,” the authors wrote.

“Without a clearer understanding of the extent of exposure, infection, viral evolution, and transmission, we will be unable to properly protect our communities from a pathogen that has proven to be a formidable challenge to human and animal health,” wrote the author of an editorial.

SOURCE:

This study was led by Shikha Garg, MD, and Katie Reinhart, PhD, Influenza Division, Centers for Disease Control and Prevention, Atlanta. It was published online on December 31, 2024, in The New England Journal of Medicine.

LIMITATIONS:

Variability in on-farm monitoring may have introduced ascertainment bias, leading to underreporting of cases. Incomplete data from case-report forms and premature data collection before symptom resolution could have skewed some results. Exposure data were unable to capture behaviors associated with increased infection risk.

DISCLOSURES:

This study was supported by the Epidemiology and Laboratory Capacity for Prevention and Control of Emerging Infectious Diseases co-operative agreement of the Centers for Disease Control and Prevention. The disclosures have been reported in the original study.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.