Modeling the cost of eradicating livestock-associated methicillin-resistant staphylococcus aureus in countries with a high proportion of positive herds.

Due to an increased incidence of human infections, livestock-associated methicillin-resistant Staphylococcus Aureus (LA-MRSA) in pigs and its spread into the human population has been a major public and political issue in Denmark. Similar concerns are also being raised about LA-MRSA in other Western European countries. At a time when the proportion of LA-MRSA-positive pig farms was low, Norway adopted a 'trace and destroy' strategy aimed at keeping LA-MRSA out of the pig population. However, to date, no country with a high proportion of LA-MRSA-positive pig herds has chosen to use an eradication strategy. This study analyses the cost and complexities of conducting an LA-MRSA eradication program in a situation where a large proportion of herds are positive. The total cost of the eradication program was estimated based on the following components: 1) planning, 2) monitoring and testing, 3) cleaning and disinfection, 4) production gains and losses, 5) net reduction in breeding exports, and 6) loss of genetic progress, including the costs of a mitigating caesarean section strategy in breeding herds. Costs were related to the depopulation of 1 million sows, to gilt supply (as this was an important limiting factor during an eradication program in Denmark), and to aggregated losses linked to a temporary halt on breeding progress. Using conservative assumptions, the total eradication costs were estimated at €1.8 billion, broken down into: planning costs (3%), monitoring and testing (6%), cleaning and disinfection (19%), production gains and losses (33%), net loss from breeding exports (19%) and loss of genetic progress (20%). The long-term effects of an LA-MRSA eradication program for Danish pig production were uncertain and were therefore not taken into account in the analysis.

A case-control study of risk factors for bovine cysticercosis in Danish cattle herds.

Bovine cysticercosis (BC) is a zoonotic, parasitic infection in cattle. Under the current EU meat inspection regulation, every single carcass from all bovines above 6 weeks of age is examined for BC. This method is costly and makes more sense in countries with higher number of BC-infected animals than in countries with few lightly infected cases per year. The aim of the present case-control study was to quantify associations between potential herd-level risk factors and BC in Danish cattle herds. Risk factors can be used in the design of a risk-based meat inspection system targeted towards the animals with the highest risk of BC. Cases (n = 77) included herds that hosted at least one animal diagnosed with BC at meat inspection, from 2006 to 2010. Control herds (n = 231) consisted of randomly selected herds that had not hosted any animals diagnosed with BC between 2004 and 2010. The answers from a questionnaire and register data from the Danish Cattle Database were grouped into meaningful variables and used to investigate the risk factors for BC using a multivariable logistic regression model. Case herds were almost three times more likely than control herds to let all or most animals out grazing. Case herds were more than five times more likely than control herds to allow their animals access to risky water sources with sewage treatment plant effluent in proximity. Case herds were also more likely to share machinery or hire contractors than control herds. The risk decreased with increasing herd size probably because the larger herds generally tend to keep cattle indoors in Denmark. The results are useful to guide future data recording that can be supplied by the farmer as food chain information and then be used for differentiated meat inspection in low- and high-risk groups, enabling development of risk-based meat inspection systems.

Epidemiologic and economic evaluation of risk-based meat inspection for bovine cysticercosis in Danish cattle.

Under the current EU meat inspection regulation, every single carcase from all bovines above 6 weeks of age has to be examined for bovine cysticercosis (BC). This is time-consuming, costly, and is of limited value in countries with low prevalence. The aim of this study was to develop a stochastic simulation model for analysis of tentative risk-based meat inspection systems for BC in Danish cattle with regard to system sensitivity (SSSe), specificity and potential monetary benefits compared to the current system, which has an estimated SSSe of 15%. The relevant risk factors used to construct three alternative scenario trees were identified from previous Danish risk factor studies (1) gender, (2) grazing and (3) access to risky water sources. Thus, females, animals that had been grazing or animals with access to risky water sources were considered high-risk and would be subjected to invasive inspection at meat inspection. All animals in the low-risk groups (i.e. males, non-grazing or no access to risky water sources, respectively) would be subjected to visual inspection only. It was assumed that half of the cattle were slaughtered in abattoirs that would be able to reorganise the work at the slaughterline, allowing them to do with one meat inspector less. All abattoirs would gain on the price of sold uncut beef from the masseter muscles from visually inspected cattle. Under these assumptions, using gender and grazing were preferable due to them having SSSe only slightly lower than the current system, and highest effectiveness ratios, but they had a lower net economic effect (NEE) than the scenario using risky water sources. Using gender to differentiate high and low-risk groups was judged preferable over grazing due to feasibility, because the information is readily available at the slaughter line. The exact total NEE for the cattle sector depends on how many and which of the abattoirs that would be able to reorganise the work at the slaughter line to save money on inspection of the head of carcases. Overall, the SSSe was low in all scenarios leading to undetected BC-positive cattle both in the current meat inspection and under the investigated risk-based meat inspection systems. Therefore, improving the sensitivity of the methods used for inspection of high-risk cattle would be beneficial.

Occurrence and factors associated with bovine cysticercosis recorded in cattle at meat inspection in Denmark in 2004-2011.

Current EU regulation requires that every bovine carcass is examined for bovine cysticercosis (BC) at meat inspection. This is costly and might be superfluous at low BC prevalence. However, from a consumer view-point it may be important to identify and manage infected carcasses to avoid human infection. If relevant data could be effectively used to classify animals with respect to their risk of being infected, then the current meat inspection could be replaced by a more cost-effective system targeting high-risk animals. This study aimed to (1) describe the distribution of BC cases in the Danish cattle population, (2) estimate the animal level prevalence (3) provide descriptive statistics of potential risk factors for BC, and (4) determine attributable risks and fractions of selected risk factors potentially useful for a future risk-based meat inspection system. In total, 348 cases of BC were recorded among all cattle slaughtered (n=4,090,661) in Denmark between 2004 and 2011. The true animal level prevalence of BC was estimated to be 0.06%. The herd of origin of the cases were defined as the herd in which the animals spent most of their lifetimes. The detected cases were found to originate from 328 herds, with a maximum of two cases per herd indicating sporadic occurrence. Even though organic farming was associated with a higher risk (RR=1.9 in univariable analysis) of BC-positive animals being detected at slaughter, the population attributable fraction showed that only 5% of the animals with BC could be attributed to organic farming practices at the level of organic farming practiced in Denmark in the study period. Thus, organic farming status was not a suitable risk factor to use to target future risk-based meat inspection. However, 54% of the animals with BC in the cattle population were attributed to female gender. Increasing age at slaughter was also associated with high risk of BC. There may be overlaps between these effects in animals with multiple risk factors. Other underlying factors such as grazing patterns might explain the risk factors and attribution results found in this study. However, grazing practices are currently not recorded in the Danish cattle database. Therefore, animal level risk factors such as age and gender together with other risk factors such as grazing practices might be included as food chain information, required to be provided by the farmer prior to slaughter. The challenges and opportunities of this approach should be investigated further.