TEXT-ONLY VERSION (scroll to bottom to download Newsletter in PDF)
The importance of biosecurity- Avian Influenza
For the next few months, we will focus on specific infectious animal diseases and why biosecurity and the proper disposal of animal remains is so important.
Avian Influenza (AI) is a highly contagious viral disease that affects bird species across the world (World Organisation for Animal Health, 2021). Circulation of AI viruses is not a new phenomenon. The disease can vary from mild to severe, depending on the viral strain involved. Two categories of AI viruses are commonly observed and referred to as low pathogenicity AI (LPAI) or high pathogenicity AI (HPAI) (Centres for Disease Control and Prevention, 2022).
AI occurs worldwide and different strains are more prevalent in certain areas of the world than others. Outbreaks have occurred in many countries, including the U.S., parts of Asia, Europe and Africa. Due to the ongoing circulation of various strains (e.g. H5N1, H5N2, H5N8, H7N8), outbreaks of AI continue to be a global public health concern.
In 2021, a record-breaking 14 million AI cases were detected. In total 61.4 million birds died from either the virus or because they were culled to limit the spread of this highly infectious disease (Newey, 2022). Experts have warned that the increase in cases (which does not appear to be as a result of improved detection/surveillance methods) poses a threat to human health. This is because it generates more opportunities for the pathogen to “jump” to and circulate in humans. Increased and frequent proximity of the virus through increased outbreaks in poultry is a risk to human health as influenza viruses can rapidly evolve and mutate.
While experts agree that this is a risk that needs to be mitigated against, it should be stressed that while there have been cases of avian influenza infecting humans – these cases are rare and are generally confined to people working in close proximity and who have had direct contact with infected poultry and other avian species. To date there has been no evidence of human-to-human transmission.
Why is biosecurity so important?
Biosecurity is a set of preventive measures designed to prevent the risk of spreading of infectious diseases. Controlling the disease at the animal source is critical to ensuring the safety of human health and thereby also decreases the risk and likelihood of an influenza pandemic. Pre-incident planning facilitates a rapid response if an outbreak occurs. Such planning includes the safe disposal of infectious animal remains. Animal remains, in sufficient numbers, present a potential environmental and public health risk.
Therefore, proper carcass management is strongly advised. In South Africa, the dumping of infectious animal remains on landfill sites is illegal (Cullinan & Associates, 2021). Burial is not advised as the virus can leach into the groundwater and surrounding environment thereby further spreading the disease. Wild animals and scavengers may also have access to the remains if burial is not done properly further spreading the disease. A closed, composting system such as that which EarthPet provides, is the key to safe and proper carcass management. No environmental contamination, temperatures high enough to neutralise the virus and no access to the remains by wildlife and scavengers are some of the advantages that this solution offers in the event of an outbreak.
Record Breaking: In 2021, a record breaking 14 million cases of AI were detected. In total 61.4 million birds died either as result of the virus or due to being culled to prevent the spread of the virus.
Economic consequences of an AI outbreak:
- Farmers may experience a high level of mortality in their flocks, this leads to a loss of income.
- The poultry industry is labour intensive & job losses will be significant.
- Healthy birds often need to be culled to contain the virus this leads to concerns regarding protein wastage and economic impacts.
- HPAI restricts international trade in live birds and poultry meat.
- Public opinion may be damaged, reducing both travel & tourism.
Avian Influenza virus deactivation temperatures:
- Low Pathogenicity 1 day @ 26.7°C
- High Pathogenicity @ 43.3°C.
Several factors contribute to the spread of AI viruses:
- Globalisation & international trade.
- Farming & sale (live bird markets).
- Wild birds & migratory routes.
Transmission of AI viruses:
- AI viruses are typically shed in the faeces and respiratory secretions.
- Direct contact with secretions of infected birds or contaminated water & feed.
- AI viruses can be carried on farm equipment, vehicles and clothes & spread easily from farm to farm.
- Wild birds are carriers for AI viruses and can spread them along their migratory routes.
Public Health Risk: Humans in direct & close contact with infected birds are at risk for acquiring Avian Influenza. Illness ranges from mild to severe. To date there has been no evidence of human-to-human transmission.
Prevention at animal source:
- Limit exposure to wild birds.
- Maintain strict control over access to flocks by vehicles, people & equipment.
- Ensure proper sanitation of property, poultry houses and equipment.
- Avoid the introduction of birds of unknown disease status into the flock.
- Report any bird illnesses and deaths to the Veterinary Services.
- Ensure appropriate disposal of manure, litter and dead birds.
- Vaccinate animals where appropriate.
Monitor & control: Implementation of biosecurity measures, is key in securing the production sector and trade, to safeguard food security and the livelihoods of farmers, and to limit the risk of human infection with avian influenza strains that have zoonotic potential.
World Organisation for Animal Health, 2021. OiE Listed: Avian Influenza. [Online]
Available at: https://www.oie.int/en/disease/avian-influenza/#ui-id-1
[Accessed 22 February 2022].
Centres for Disease Control and Prevention, 2022. Infleunza (Flu) – Bird Flu in Birds. [Online]
Available at: https://www.cdc.gov/flu/avianflu/avian-in-birds.htm
[Accessed 22 February 2022].
Newey, S., 2022. The Telegraph. [Online]
Available at: https://www.telegraph.co.uk/global-health/science-and-disease/exclusive-bird-flu-surge-threat-human-health-experts-warn/
[Accessed 23 February 2022].
Cullinan & Associates, 2021. EarthPet – Legal regulations. [Online]
Available at: https://earthpet.co.za/legal-regulations/
[Accessed 23 February 2022].