2024-09-26-世界卫生组织-Influenza_at_the_human-animal_interface_summary_and_assessment,_27_September_2024_12页_307kb

Influenza at the Human-Animal Interface: Summary and Risk Assessment (20 July to 27 September 2024)

Overview

• Surveillance: Detected influenza viruses include A(H5), A(H9N2), A(H3N2)v, A(H1N1)v in humans.
• Animal Surveillance: High pathogenicity avian influenza (HPAI) continues to be reported in poultry and non-poultry animals globally by WOAH and FAO, with significant activity in the U.S. and Cambodia, impacting diverse species.

Human Cases (July 20 - Sep 27, 2024)

• A(H5): 19 confirmed cases, primarily USA (6 cases) and Cambodia (3 cases), associated mainly with contact with infected poultry/farms. All cases mild to severe but not indicating sustained human-to-human transmission.
• A(H5N1): 8 officially reported cases (included in A(H5)), strains circulating show limited human adaptation and no increased severity markers.
• A(H9N2): 2 cases reported, USA and China. Mild clinical presentations. No sustained transmission linked.
• A(H9N2): 1 case reported from Ghana, first in the country, similar findings to China case.
• Swine Influenza (A(H1N1)v): 5 cases reported, all in USA and Viet Nam. Occupational/contact exposure noted, mild cases.
• Swine Influenza (A(H1N2)v): 1 case reported in USA.
• Swine Influenza (A(H3N2)v): 5 cases reported in Canada and USA. Occupational/contact exposure noted, mild cases.

Risk Assessment

• Overall: The overall public health risk from known influenza viruses at the human-animal interface remains unchanged; sustained human-to-human transmission is considered unlikely.
• Specific Viruses:
  • A(H5) / A(H5N1):
    1. Additional Human Cases: Low public health risk due to association with animal contact.
    2. Sustained Human-to-Human Transmission: Unlikely.
    3. International Spread: Unlikely beyond travelers returning from outbreaks.
  • A(H9N2):
    1. Additional Human Cases: Low public health risk.
    2. Sustained Human-to-Human Transmission: Unlikely.
    3. International Spread: Unlikely.
  • Swine Influenza (A(H1N1)v, A(H1N2)v, A(H3N2)v):
    1. Additional Human Cases: Low public health risk due to association with animal contact.
    2. Sustained Human-to-Human Transmission: Unlikely.
    3. International Spread: Unlikely beyond travel.

Risk Management

• Surveillance: Emphasize global strategic surveillance in both animal and human populations for influenza viruses.
• Zoonotic Influenza: Enhanced surveillance in birds (including HPAI as a differential), livestock (monitor non-avian species), use biosecurity/hygiene measures. Notify WOAH for HPAI cases.
• Human Case Notification: All human infections with a new influenza A subtype must be reported under IHR (2005). Viruses with pandemic potential should be shared promptly via the PIP Framework.
• Risk Reduction: Public advised to avoid contact with sick/dead/unknown animals, practice good food hygiene/pasteurization. Travellers advised to avoid live-animal markets, contact with animals, ensure handwashing.

Links and Further Information

• WHO: Avian & zoonotic influenza pages, Case definitions, Investigation protocols, Public health resource packs, confirmed A(H5N1) cases page.
• WOAH: Avian Influenza web page.
• FAO: Avian Influenza information page.
• OFFLU database.