If it is assumed that the loss associated with introduction of a catastrophic infection into a one-million hen complex is $10 million and the levels of protection provided by the combination of Structural and Operational biosecurity are repectively 80 percent and 20 percent, the two levels of loss can be expressed as:-
- 0.8 = 0.2 for an investment of $200,000 or
- 0.5 = 0.5 for an investment of $50,000
If it is assumed that there is a 0.1 probability of exposure, the loss sustained by a producer would be:-
Quantum of loss x probability of infection x level of loss
$10 million x 0.1 x 0.2 = $200,000
The relatively low level of Structural and Operational Biosecurity costing $50,000 would contribute to the following loss in the event of exposure:-
$10 million x 0.1 x 0.5 = $500,000
The difference between the theoretical losses associated with the high and low levels of investment would be $300,000 per outbreak.
The difference between investment in the high and low levels of biosecurity is $150,000.
The benefit to cost ratio at the 0.1 probability of infection is therefore $300,000 ÷ $150,000 = 2:1
The benefit to cost ratio can be calculated for a range of probabilities extending from 0.1 to 1.0 yielding benefit to cost ratios of 2:1 extending to 10:1.
The boilerplate conceptual model described above can be adapted to specific situations. Obviously the higher the risk of infection such as location in an area with a high concentration of susceptible poultry, proximity to large expanses of water which attracts migratory birds and proximity of farms dictate a proportionately higher level of Structural and Operational Biosecurity as evidenced by events in Iowa and Nebraska during the 2015 May to June epornitic.
It is possible using realistic costs and reasonable assumptions to quantify potential losses associated with specific diseases and to select an appropriate level of investment which provides a quantifiable return.
*Gifford, D.H., Shane, S.M., Hugh-Jones, M.E. and Weigler, B.J. (1987). Evaluation of Biosecurity in Broiler Breeders. Avian Diseases 31; 339-344