ETIDIOH - NEW

Abstract Background Every year, more than one billion people around the world are infected with influenza , an acute infection of the respiratory tract. Influenza spreads from person to person through air, contaminated hands or objects. Antiviral and immunomodulatory drugs are available for treatment of patients and prophylaxis of exposed persons. Reverse transcription polymerase chain reaction (RT-PCR), nucleic acid amplification tests (NAATs) and rapid tests are available for the diagnosis of influenza.  Objective   The aim of this World Health Organization (WHO) guideline is to provide recommendations for the diagnosis, drug treatment and prophylaxis of influenza. Method This updated guideline has been developed in accordance with standards for trustworthy guidelines. The recommendations are based on systematic reviews on safety and effectiveness. They take into account the magnitude of benefits and harms of treatments, the reliability of the evidence, and the needs of pati...

Abstract Highly pathogenic avian influenza (HPAI) A(H5N1) clade 2.3.4.4b was first detected in birds in the United States in 2021 and an ongoing outbreak in dairy cattle began in early 2024. At least 70 U.S. cases have been identified in humans with exposure to infected cattle, poultry, and wild birds. No human-to-human transmission has been documented . However, as part of diagnostic preparedness, we evaluated the ability of currently available influenza tests to detect 2024 U.S. H5N1 strains. Contrived nasal swab samples were prepared using live or inactivated 2024 H5N1 and used to test twelve rapid antigen tests (lateral flow assays, or LFA), including 10 commercially-available influenza A LFAs and two H5-specific LFAs. Five point-of-care (POC) molecular assays were also tested. An inclusivity testing protocol was used, wherein a predetermined dilution series is used to evaluate each assay, enabling head-to-head comparison of assay performance. All lateral flow assays and POC molecu...

Key points   • The overall objective of continual global surveillance for human infection with avian influenza A(H5) viruses is to detect and characterize any influenza A(H5) viruses infecting humans in order to:  - (1) promptly trigger public health control and response actions,  - (2) assess the trends of such infections and the public health risks posed (including the risk of a pandemic); and  - (3) inform global pandemic preparedness activities.  • Specific surveillance objectives include rapidly detecting human cases of influenza A(H5) virus infection, monitoring the incidence of new cases over time and geographical distribution, assessing and monitoring changes in transmission patterns to promptly detect any unusual events that may signal human-to-human transmission of the virus, characterizing and monitoring changes in any influenza A(H5) viruses infecting humans relative to those circulating in animals to inform control strategies, describing the clinica...

Highlights •  Impact of genetic evolution in influenza A(H1N1)pdm09 on subtyping assay performance. •  Influenza A subtyping assays are susceptible to primer- or probe-binding mismatches. •  Subclades 6B.1 A.5a.2a.1 and 6B.1 A.5a.2a harbour mutations that caused subtyping failures in some specimens. •  Sequencing confirmed all specimens were H1N1pdm09, within recognized subclades. Abstract Background During the 2023–2024 and early 2024–2025 influenza seasons , several influenza A-positive specimens in our laboratory failed subtyping for H1 , H1pdm09, and H3 using the Allplex Respiratory Panel 1 (Allplex RP1) (Seegene Inc.). This study aimed to identify the cause of these subtyping failures. Materials and Methods Between August 2023 and December 2024 , 23 nasopharyngeal specimens tested positive for influenza A but were unsubtypeable for H1, H1pdm09, and H3. Confirmatory testing by the manufacturer included target-specific PCR for the M and HA genes, followed by seque...

Abstract Highly pathogenic avian influenza A(H5N1) virus has caused a multistate outbreak among US dairy cattle , spreading across 16 states and infecting hundreds of herds since its onset. We rapidly developed and optimized PCR-based detection assays and sequencing protocols to support H5N1 molecular surveillance . Using 214 retail milk samples from 20 states for methods development, we found that H5N1 virus concentrations by digital PCR strongly correlated with quantitative PCR cycle threshold values ; digital PCR exhibited greater sensitivity. Metagenomic sequencing after hybrid selection was best for higher concentration samples, whereas amplicon sequencing performed best for lower concentrations. By establishing these methods, we were able to support the creation of a statewide surveillance program to perform monthly testing of bulk milk samples from all dairy cattle farms in Massachusetts , USA, which remain negative to date. The methods, workflow, and recommendations described p...

Abstract A sustained outbreak of H5N1 influenza virus among wild fowl and domestic livestock has caused more than 70 zoonotic infections in humans in the United States , including one death. The Centers for Disease Control and Prevention has recommended rapid H5 subtyping for all hospitalized cases with influenza A virus infection to enable prompt initiation of antiviral treatment , as well as infection prevention and implementation of public health measures to control spread. To address these needs, we developed a multiplex RT-qPCR assay to subtype H5 influenza virus in nasal, nasopharyngeal, and conjunctival specimens with a limit of detection of 230 copies/mL. No cross-reactivity was observed with other common respiratory viruses, including seasonal H3N2 and H1N1 influenza A viruses. We retrospectively subtyped 590 influenza A-positive clinical specimens processed by University of Washington labs between March 2024 and February 2025, including 512 specimens collected during the 2024...