A child in Bangladesh died after contracting a highly pathogenic strain of bird flu in January, while cases of multiple zoonotic influenza subtypes were confirmed across Asia, Europe, and South America in the first quarter of 2026 — the latest reminder that the boundary between animal and human influenza remains an active frontier for pandemic surveillance.
The World Health Organization (WHO) released its quarterly human-animal interface influenza summary on March 31, 2026, covering the period from January 23 to March 31. The report documents confirmed human infections with influenza A(H5N1), A(H9N2), A(H10N3), and three swine-origin variant strains across Bangladesh, Cambodia, China, Italy, and Brazil. Despite the geographic breadth of detections, WHO assessed the overall public health risk as low, with no evidence of sustained human-to-human transmission linked to any of the reported cases.
Fatal H5N1 Case in Bangladesh, Cluster in Cambodia
The most serious outcome reported in the period was the death of a child in Bangladesh’s Chattogram Division. The patient developed symptoms on January 21, was admitted to hospital on January 28, and died on February 1 after a rapid deterioration requiring intensive care. Testing by the Institute of Epidemiology, Disease Control and Research (IEDCR) confirmed the virus belonged to clade 2.3.2.1a — the clade circulating in local poultry since around 2011. Samples from household ducks and frozen chicken tested positive for influenza A(H5), and the child had known exposure to backyard poultry that died shortly before the child fell ill. Close human contacts tested negative.
In Cambodia, three human cases of A(H5N1) were confirmed between February 15 and March 31 — a 30-year-old male who recovered, a 45-year-old female who was asymptomatic, and a 3-year-old male still hospitalized at the time of reporting. All had exposure to sick or dead backyard poultry. Viruses from the Cambodian cases were identified as clade 2.3.2.1e, consistent with strains circulating in local birds. WHO found no indication of human-to-human transmission among these cases.
H9N2 Detected in Europe for the First Time via Returning Traveler
One of the report’s more notable findings was the detection of influenza A(H9N2) in an adult male in Italy — the first imported human case of this subtype reported in the European Region. The patient had lived in Senegal for more than six months, returning to Italy in mid-March 2026 with fever and persistent cough dating back to mid-January. He was co-infected with Mycobacterium tuberculosis. Genomic sequencing identified the H9N2 strain as closely related to strains previously identified in poultry in Senegal. No direct animal exposure was identified, and all contacts in both countries tested negative.
An additional four H9N2 cases were reported from China — two in children under five, and two in older adults with underlying conditions — all of whom recovered. China also reported a single case of avian influenza A(H10N3) in a 34-year-old man from Guangdong who developed severe pneumonia and ARDS. He was the seventh confirmed human case of H10N3 globally since 2021, with all cases originating in China.
Swine-Origin Strains Detected in China and Brazil
Three human cases involving swine-origin influenza variant viruses were also documented. Two occurred in children in China’s Yunnan province — one with A(H1N1)v and one with A(H1N2)v — both with reported pig exposure and neither epidemiologically linked. A third case involved a child in Brazil’s Mato Grosso do Sul state infected with A(H3N2)v, confirmed after the child fell ill in September 2025 while attending an agricultural school where pigs are raised. The case was confirmed in January 2026 following genomic sequencing at Brazil’s National Influenza Center and additional characterization at the U.S. CDC.
Why This Surveillance Matters for Global Health Security
The quarterly report underscores the persistent and geographically diffuse nature of zoonotic influenza activity. While individual spillover events carry low pandemic risk, their collective pattern — spanning multiple subtypes, multiple host species, and multiple continents — illustrates why sustained surveillance at the human-animal interface is considered a cornerstone of pandemic preparedness. The Italy case in particular demonstrates the potential for zoonotic influenza to appear in non-endemic regions through international travel, without any identifiable direct animal contact.
WHO’s risk management guidance emphasized the need for continued global surveillance in both animals and humans, timely virus sharing with WHO Collaborating Centres under the Pandemic Influenza Preparedness Framework, and the maintenance of candidate vaccine viruses for zoonotic strains — updated most recently at the February 2026 WHO vaccine composition consultation.
The agency also reiterated that no special traveler screening or trade restrictions are warranted at this time, but advised travelers visiting areas with known animal outbreaks to avoid contact with live animals and markets.
Sources and further reading:
Influenza at the human-animal interface: Summary and risk assessment, from 23 January to 31 March 2026 – World Health Organization