2004-07-15-世界卫生组织-Weekly_epidemiological_record,_2004,_vol._79,_29_full_issue_8页_240kb

2004, 79, 265–272

Avian Influenza – Current Evaluation of Risks

• The H5N1 virus has become increasingly pathogenic and widespread in birds, raising concerns due to its ability to directly infect humans.
• Outbreaks began re-emerging in poultry in several Asian countries in late 2003–early 2004, coinciding with reported human infections in Hong Kong and Vietnam.
• Symptoms range from mild illness to rapidly fatal disease, especially in humans, with high mortality rates. Infected birds shed the virus for up to 10 days, facilitating transmission.

Key Concerns and Risks

1. Zoonotic Transmission: The virus can jump from birds to humans, and mutations may enable human-to-human transmission, potentially leading to a devastating pandemic.
2. Recent Outbreaks: Higher prevalence and spread of H5N1 were reported in regions like Asia, highlighting the need for containment.
3. Mutation and Adaptability: H5N1 mutates rapidly and can acquire genes from other influenza viruses, increasing its virulence.

Recommendations and Actions

• Risk Management: Control measures include culling infected poultry, strict surveillance, and public health interventions such as antiviral prophylaxis and vaccination programs.
• WHO Actions: Urged nations to enhance surveillance, share virus samples with the WHO laboratory network, and prepare for early detection and containment.
• Pandemic Preparedness: Collaboration with international agencies (like FAO and OIE) to monitor the virus and develop novel antivirals and vaccines.

Immediate Priority

Prevent further human exposure by:

• Protecting high-risk groups (e.g., culling workers) through antivirals and personal protective equipment.
• Vaccinating against human influenza strains to reduce co-infection risks with avian influenza.

Summary of Outbreak Timeline and Concern Factors:

• H5N1 Status: Found in wild and domesticated birds, increasing difficulty for eradication.
• Human Cases: Confirmed cases in Southeast Asia and Europe, signaling potential global risk.
• Call for International Cooperation: WHO requested enhanced international coordination for surveillance, data sharing, and pandemic readiness, emphasizing the urgency to address any gateway for human-to-human transmission.

Other Vaccines and Safety Topics

• Adjuvant safety assessments in novel vaccines require defined pharmacological tolerability testing to evaluate long-term and rare adverse events.
• Dengue vaccine safety concerns highlight challenges in balancing immunity and risks of severe disease, particularly in children.
• DTP vaccination reconsidered in relation to childhood mortality (no substantiated deleterious effects).

Conclusion

The H5N1 influenza virus remains a significant global health risk due to its zoonotic potential,highly pathogenic nature, and increased prevalence. Immediate and sustained international monitoring, research, and control measures are essential to prevent a future pandemic.