N Engl J Med

Highly pathogenic avian influenza A(H5N1): Key signs & symptoms

January 3, 2025

A review of 46 lab-confirmed A(H5N1) virus infections in the U.S. revealed:

• Symptoms. Conjunctivitis in 93% (33% had conjunctivitis as the only symptom), fever in 49%, and respiratory symptoms in 36%.
• Demographics. 45/46 cases involved animal exposures: 20 were exposed to infected poultry, 25 to dairy cows. Median age was 34 years in these patients. Protective equipment commonly used by these workers included eye protection (60%), gloves (71%), and face masks (47%). The sole patient without animal exposure was a hospitalized patient whose routine surveillance testing was positive for A(H5N1).
• Severity. Patients with animal exposure all had mild illness not requiring hospitalization; there were no deaths.
• Duration of illness. 4 days (range, 1 - 8) in the 16 patients for whom data were available.
• Treatment. Most patients were prescribed oseltamivir, which was initiated a median of 2 days post-onset of symptoms.
• Human contacts. There was no evidence of human-to-human transmission; no cases were detected among 97 household contacts of patients with animal exposures.

Source:

Garg S, et al. (2024, December 31). N Engl J Med. Highly Pathogenic Avian Influenza A(H5N1) Virus Infections in Humans. https://pubmed.ncbi.nlm.nih.gov/39740051/