What is the impact of Highly Pathogenic Avian Influenza (HPAI) on humans and animals?

From the Guidelines

Highly Pathogenic Avian Influenza (HPAI) has a significant impact on both humans and animals, with high mortality rates in humans (up to 60% for H5N1 strains) and devastating effects on poultry with mortality rates often exceeding 90%. In humans, HPAI can cause severe respiratory illness with symptoms including fever, cough, sore throat, and in serious cases, pneumonia, respiratory failure, and death, as reported in studies such as 1. Human infections are rare but occur primarily through direct contact with infected birds or their environments. The treatment typically involves antiviral medications like oseltamivir (Tamiflu) at 75mg twice daily for 5 days, started as early as possible.

For animals, especially poultry, HPAI is devastating, spreading rapidly through flocks and causing symptoms like decreased egg production, respiratory distress, swelling, and sudden death. Control measures include culling infected flocks, quarantine, and strict biosecurity protocols, as outlined in guidelines such as 1 and 1. HPAI viruses can mutate rapidly, potentially increasing transmissibility between humans, which is why global surveillance is critical, as noted in 1. Prevention focuses on avoiding contact with sick birds, proper handling of poultry products, and vaccination of poultry in some regions.

Key points to consider include:

• The high mortality rate associated with HPAI in humans, particularly with the H5N1 strain, which can reach up to 60% 1.
• The rapid spread and high mortality rate of HPAI in poultry, often exceeding 90% 1.
• The importance of global surveillance due to the potential for HPAI viruses to mutate and increase transmissibility between humans 1.
• The need for strict biosecurity protocols, including culling infected flocks and quarantine, to control the spread of HPAI in poultry 1.

From the Research

Impact of HPAI on Humans

• HPAI H5N1 has caused significant outbreaks in humans, with 878 cases and 458 fatalities reported between 2003 and 2023 2
• The virus has been transmitted to humans through contact with infected birds, and there is a risk of transmission through other mammalian hosts, such as cattle 3
• The immune response against HPAI H5N1 and its implications for vaccine development are being studied, with a focus on understanding the molecular composition and key structural features of the virus 2

Impact of HPAI on Animals

• HPAI is a highly contagious and deadly disease in poultry, with high morbidity and mortality rates 4, 5
• The virus has been reported in various animal species, including wild birds, domestic birds, sea lions, minks, and cattle 2, 3
• The emergence and selection of HPAI viruses in animal populations is a complex process, involving mutations in the hemagglutinin cleavage site and other genetic changes 6

Transmission and Epidemiology

• HPAI outbreaks have been reported in many countries, with two major global peaks in the number of countries affected in 2006 and 2016 5
• The virus can spread through contact with infected birds, as well as through other routes, such as contaminated feed and water 4
• The distance and rate of spread of HPAI outbreaks are influenced by various factors, including the number of outbreaks and the effectiveness of control measures 5

Prevention and Control

• Prevention of exposure to the virus and eradication are the accepted methods for dealing with HPAI outbreaks 4
• Control programs, including surveillance, biosecurity, education, quarantine, and depopulation, are essential for managing HPAI outbreaks 4, 5
• Vaccination has been used in some control and eradication programs for AI, and is being studied as a potential tool for preventing HPAI outbreaks in humans and animals 4, 2