Economic value of mitigating Actinobacillus pleuropneumoniae infections in pig fattening herds

Actinobacillus pleuropneumoniae infections (APP) can cause severe economic losses in pig production. Swine producers can prevent the disease from occurring and spreading. However, to be profitable for the producer, the anticipated benefits of a mitigation policy should exceed its cost. In this study, a dynamic programming model and multivariate normal approximation of general stochastic epidemic model (SIR) was developed, and policies for managing fattening pigs under the risk of APP infection were evaluated. The following disease mitigation options were considered: 1) cleaning including washing, drying and disinfection procedures (for efficient and inefficient cleaning), 2) cleaning and vaccination (with high, medium and low efficacy of vaccine), and 3) cleaning and medication (antibiotics use). The results were calculated for five different levels of APP prevalence, where the disease can occur at ten levels of severity. The economic value of mitigation policy depended on the prevalence and severity of disease as well as on the efficiency of the implemented mitigation protocol. The results suggest that inefficient cleaning caused substantial economic losses which can reach up to €20.2 per pig space unit per year. The cleaning and vaccination policy was economically superior over the policy of only cleaning when the prevalence of disease was high (> 0.3), there was a severe clinical disease and the medium or high efficacy vaccine was available. Moreover, even when vaccination costs were decreased the vaccination policy was not economically favored in situations with low disease prevalence among herds (0.1 and 0.3). In cases of severe disease, the cleaning and medication policy resulted in higher economic benefits than cleaning or cleaning and vaccination with low and medium efficacy vaccine. With a high prevalence (> 0.3) and substantial decrease in the average daily gain (ADG), the joint application of cleaning and medication was economically less favorable than cleaning combined with the use of the high efficacy vaccine. Therefore, the availability of high efficacy vaccine could benefit farms facing the severe forms of APP and help to reduce the use of antibiotics. To avoid substantial economic losses, pig producers should not ignore cleaning procedures, which due to low efficacy of available vaccines and concerns regarding excessive use of antibiotics and antibiotic resistance in animal production should be the primary policy to mitigate APP.