19.12.2024

Emerging Infectious Diseases | 2024

A new study published in Emerging Infectious Diseases reports a case of Highly Pathogenic Avian Influenza (HPAI) H5N1 infection in a traveler returning to Australia from India. The patient, a 2.5-year-old girl, fell ill after visiting Kolkata, India, and was hospitalized upon her return to Australia. The infection was confirmed via PCR testing, and she successfully recovered following treatment with oseltamivir.
Although poultry outbreaks of H5N1 are common, human infections with clade 2.3.2.1a HPAI H5N1 viruses remain rare, with only two documented cases prior to this report. Genetic analysis revealed the virus retained avian-like characteristics with no markers of mammalian adaptation, suggesting its primary risk lies with avian hosts.
Clade 2.3.2.1a is distinguished by unique genetic features, including specific hemagglutinin (HA) gene sequences, indicating distinct evolutionary pathways. Phylogenetic analysis showed the virus to be a reassortant, with four genomic segments resembling those of clade 2.3.2.1a viruses circulating in Bangladesh. The virus exhibited preferential binding to avian α2–3 sialic acid receptors rather than mammalian α2–6 receptors, consistent with its avian origin.The prevalence of clade 2.3.2.1a is associated with poultry outbreaks in South Asia, raising concerns about its potential to cause zoonotic infections.