Prevention of HPAI in Poultry – Ohio Ag Net

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By Lingying Zhao

While we are still in the COVID-19 pandemic, an outbreak of ‘bird flu’ caused by the avian influenza (AI) virus first broke out in wild birds and then in domestic poultry in February of this year. AI viruses have two strains: low pathogenic strains (LPAI) or highly pathogenic strains (HPAI). HPAI strains are highly infectious, cause high bird mortality, and can spread rapidly. The strains currently prevalent in the United States are HPAI. So far, the HPAI outbreak has affected 372 flocks of 40.09 million birds in 36 states. Once HPAI is detected on a farm, all birds should be depopulated. A farm in Iowa had canceled more than 5 million birds after the HPAI virus was detected. The HPAI outbreak has resulted in significant economic losses and raises animal health, food safety and human health concerns. The vaccine is under development, although there are still significant challenges to developing a vaccine that effectively targets incoming strains of HPAI. Biosecurity control is crucial, current USDA biosecurity measures cannot effectively stop transmission of the HPAI virus.

For effective control of HPAI, let’s first review the scientific facts related to the HPAI virus. First, HPAI viruses like cool, moist conditions, especially in the presence of organic matter. The World Organization for Animal Health (OIE) has demonstrated that AI viruses can live for long periods in water, dry and moist feces and soil at room temperature. Conversely, hot and dry conditions can quickly inactivate AI viruses.

HPAI viruses are spread by direct contact between birds, by indirect contact via contaminated environment, such as equipment, clothing and footwear, animal bedding, manure, water, feed, agricultural material.

Based on the above knowledge, the following biosecurity measures and engineering control strategies are suggested by the USDA Animal and Plant Health Inspection Service (APHIS) to prevent and control the spread of HPAI in poultry production.

Current USDA APHIS biosecurity measures include structural biosecurity and operational biosecurity. Structural biosecurity measures use physical construction and maintenance to prevent wildlife from accessing poultry facilities, water surfaces, and land surfaces through a series of specific strategies (https://www.aphis.usda. gov/animal_health/downloads/animal_diseases/ai/hpaifactsheet_wildlife-biosecurity.pdf).

Operational measures implement practices and policies, such as preventing contact with wild birds, reducing the number of visitors, washing hands before and after contact with birds, providing disposable shoe covers and/or disinfectant footbaths for workers and visitors, changing clothes before entering and exiting poultry facilities; clean and disinfect tools or equipment before moving them to a new poultry facility, check for signs of illness, and report sick birds (https://agri.ohio.gov/divisions/animal-health/resources/02.25. 2022HPAIUpdate).

Once infected, depopulation will be implemented within a short period of time. Thorough cleaning of animal facilities to remove any biomaterial from poultry facilities is crucial. During dry and/or wet cleaning, precautions are necessary not to aerosolize the virus.

Then heat the barns to raise the ambient temperature to 100 to 120 degrees F for 7 days with at least three consecutive days to clear the virus from infected animal facilities.

Drying and heating are effective in destroying/eliminating the virus. Finally, properly

Disposal of poultry litter and/or manure through the composting process is also crucial to prevent the spread of the virus.

An important route of viral transmission, which has been overlooked, is airborne transmission of the virus. Like COVID-19, HPAI viruses can also be airborne and transmitted through droplets and/or dust particles generated by birds flapping wings, scratching surfaces, shaking heads and dropping manure from infected wild birds or infected domestic birds in poultry facilities. Virus attached to droplets or dust particles can be transported over long distances and remain alive for long periods of time depending on the initial velocities and sizes of the droplets or dust particles, and ambient environmental conditions (velocity of airflow). air, air temperature and relative temperature). humidity).

Most large-scale operations use enclosed buildings with automatic environmental control systems. It is difficult for domestic birds to have direct contact with wild birds. However, numerous incidences of HPAI infections have occurred over the past four months in fully enclosed poultry facilities with modern environmental control systems. Once USDA APHIS biosecurity measures are fully implemented, the only remaining route of viral transmission is airborne transmission of HPAI through dust-laden airflow through air inlets buildings. This hypothesis may explain the reason for the fact that that year the infection occurred sporadically in farms with no connection between the infected farms. At a United Egg Farmers (UEP) meeting, some farmers also thought their poultry houses were infected with dust-laden inlet airflow and demanded that cleaning and disinfection technologies be used. are developed. UEP also advises farmers to avoid creating dust around the farm and louvers on exhaust fans and barn air inlets.

The Ohio State University (OSU) Air Quality and Bioenvironmental Engineering Laboratory has conducted research to optimize electrostatic precipitation-based technologies to control duct emissions in commercial poultry facilities over the past of the last five years. We have developed electrostatic precipitators and electrostatic spray scrubbers to mitigate dust emissions from manure strip poultry houses. An interesting side effect of electrostatic precipitation dust control technologies is their varied pathogen control capabilities. We are proposing research projects to the USDA Sustainable Farming Systems Grant Program to further optimize electrostatic precipitation technologies for HPAI virus deactivation, particularly at poultry house air inlets to protect egg-laying facilities from virus infection during the HPAI outbreak. Increasingly frequent outbreaks of HPAI and other airborne diseases require that new pathogen control methods be developed to better protect the economic interests of poultry facilities and bird health.

In summary, the highly pathogenic avian influenza virus (HPAI) has seen two major outbreaks in the United States in the past decade alone. These outbreaks have depopulated tens of millions of birds and cost the poultry industries billions of dollars. HPAI viruses like cool, moist conditions and can potentially be airborne. Current USDA APHIS biosecurity measures cannot effectively stop the spread of HPAI. We may have overlooked an important viral transmission route, airborne transmission. Many incidences of current infections on the farm indicate the possibility of airborne transmission of HPAI. OSU offers research to the USDA Sustainable Agricultural Systems Grant Program to optimize electrostatic precipitation technologies for the control of airborne HPAI pathogens.

Lingying Zhao, professor and agricultural extension engineer, can be contacted at zhao.119@osu.edu. This column is provided by OSU’s Department of Food, Agricultural and Biological Engineering.

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