Risk factors in poultry production systems L. D. Sims - - PowerPoint PPT Presentation

Risk factors in poultry production systems

• L. D. Sims

apvis@bigpond.net.au

Risk of incursion

• The risk of incursion of H5N1 HPAI viruses

(or other pathogens) into a farm is determined by:

• the number of ‘contacts’/links with the

world outside the farm

• the probability of each of these ‘contacts’

involving infected or contaminated material

Risk of virus incursion

• This depends on the level of infection in

the area (hard to measure and varies over time) …

• And the measures taken to reduce the

likelihood of infection on/in items that enter the farm (e.g. water treatment , change of clothes, etc)

Risk of virus incursion

• Each individual farm or flock has its own

risk profile for introduction of pathogens and subsequent development of disease

• This is influenced by a number of factors,

including the density of farms (density-

dependent (airborne) and density-independent pathogens)

Biosecurity

• “All measures taken to prevent incursion

and spread of disease/pathogens”

• “Biosecurity means taking steps to ensure

good hygiene practices are in place so that the risk of a disease occurring or spreading is minimized” Defra UK

Farm biosecurity measures

• Location
• Physical
• Operational
• Disease can occur as a result of

inattention to any of these

• Industrial integrated system with high level

biosecurity and birds/products marketed commercially (low risk, high impact)

Poultry production system 1

• Highly sophisticated biosecurity measures
• Often international linkages (operating in

more than one country)

• Strong political connections (trust)
• High level of inputs and outputs
• Prepared to relocate to more isolated sites
• High impact if outbreak occurs

• Commercial non-integrated poultry production

system; ‘moderate to high biosecurity’; birds and products marketed commercially

• Commercial poultry production system; minimum
• r very low biosecurity; marketing via live bird

markets

Poultry production system 3

• Minimal investment in biosecurity measures
• Sometimes due to lack of capital or lack of
• wnership of facilities
• Some develop from smaller flock
• Opportunistic
• Often linked to live poultry markets
• Some production methods cannot be made

biosecure without totally changing the method of production (e.g. grazing ducks)

• Village or back yard production

(scavenging) - no biosecurity, informal marketing

Poultry production system 4

• In some places limited links to formal

market chain and in isolated communities very low risk (unless wild birds involved)

• Attempts to fence scavenging poultry

make no sense to poultry owners

What has H5N1 HPAI taught us?

• Classifying all industrialised poultry farms

together, without regard to the biosecurity measures implemented is unhelpful (provides

no indication of the likelihood of disease outbreaks on individual farms)

• This simplistic approach has been adopted

by many of those critical of ‘intensive production” and its purported role in H5N1 HPAI

What has H5N1 HPAI taught us?

• Most reports of H5N1 HPAI outbreaks in

intensively reared poultry in Asia provide insufficient detail on the biosecurity measures practiced to assess whether disease occurred as a result of poor management or the level of infection around the farm overwhelmed otherwise ‘reasonable’ measures

What has H5N1 HPAI taught us?

• In some situations, on-farm biosecurity

measures alone are not enough to prevent infection and disease (e.g. Hong Kong) – combination of improved biosecurity with vaccination

• Outbreaks may depend on a series of low

probability events

What has H5N1 HPAI taught us?

• ‘Blame’ for Asian-lineage H5N1 HPAI outbreaks

cannot be attributed to any one production system (but note role of domestic ducks and poorly regulated live

poultry markets)

• Farms in all systems have been affected and

played some role in the persistence and spread

• f this disease
• Although more cases of HPAI are generally

found in system 3 flocks there is insufficient accurate data to allow comparisons of susceptibility of different farm types

(denominator data and ascertainment bias)

Risk analysis

• Done informally in establishing biosecurity

measures

• Should be done more often for farms
• Will highlight large gaps in knowledge

regarding the level of hazard to farms

• Should follow standard steps
• Qualitative, but can still measure certain

aspects especially the effects of interventions

Biocontainment

• Most farmers focus on preventing entry of

pathogens and less about preventing

• nward spread
• Major issue in areas with high poultry farm

density

• Role for government in regulation and

enforcement

Enhancing farm biosecurity

• Market forces (& self interest)
• Regulation (and cost sharing for emergency disease)
• Communication/persuasion (get message right)
• Threat of litigation? (not yet but look at food safety

in the US after E.coli O157)

• Like buying insurance

The future

• Loss of public tolerance for control through

mass culling

• Pressure on areas with high

concentrations of farms

• Pressure on system 3 (more contract growing?)

The future

• Greater enforcement/regulation
• Use of complementary measures if

needed for ‘high risk’ production systems rather than their elimination

? ?