Spatial analysis and temporal trends of porcine reproductive and respiratory syndrome in Denmark from 2007 to 2010 based on laboratory submission data

Abstract

BackgroundPorcine reproductive and respiratory syndrome (PRRS) has been a cause for great concern to the Danish pig industry since it was first diagnosed in 1992. The causative agent of PRRS is an RNA virus which is divided into different genotypes. The clinical signs, as well as its morbidity and mortality, is highly variable between herds and regions. Two different genotypes of PRRS virus (PRRSV) are found in Denmark: type 1 and type 2. Approximately 40 % of Danish swine herds are seropositive for one or both PRRSV types. The objective of this study was to describe the temporal trend and spatial distribution of PRRSV in Danish swine herds from 2007 to 2010, based on type-specific serological tests from the PRRS surveillance and control program in Denmark using the results stored in the information management system at the National Veterinary Institute, Technical University of Denmark (DTU Vet).ResultsThe average monthly seroprevalence of PRRSV type 1 was 9 % (minimum of 5 %; maximum of 13 %) in breeding herds, and 20 % (minimum of 14 %; maximum of 26 %) in production herds; PRRSV type 2 had an average seroprevalence of 3 % (minimum of 1 %; maximum of 9 %) in breeding herds and of 9 % (minimum of 5 %; maximum of 13 %) within production herds. The seroconversion rate followed a similar and consistent pattern, being higher for type 1 than for type 2 for both PRRSV types. Regarding the spatiotemporal results, the relative risk distribution maps changed over time as a consequence of the changes in PRRSV seroprevalence, suggesting a general decline in the extent of areas with higher relative risk for both type 1 and 2. Local spatial analysis results demonstrated the existence of statistically significant clusters in areas where the relative risk was higher for both herds.ConclusionsPRRSV type 1 seroprevalence was constantly higher than for PRRSV type 2 in both herd types. Significant spatial clusters were consistently found in Denmark, suggesting that PRRSV is endemic in these areas. Furthermore, relative risk distribution maps revealed different patterns over time as a consequence of the changes in seroprevalence.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0617-0) contains supplementary material, which is available to authorized users.

Outcomes From Using Mortality, Antimicrobial Consumption, and Vaccine Use Data for Monitoring Endemic Diseases in Danish Swine Herds

“…More detailed studies are needed to determine whether the changes in these data streams also reflect other types of Danish swine herds, such as another type of SPF farm or non-SPF farms, where the prevalence of endemic diseases is higher compared to Red-SPF farms (8, 23). Additionally, other monitoring methods more suitable for monitoring gradual changes in data (with missing observations) for multivariate monitoring need to be evaluated.…”

“…Danish SPF-herds are tested on a regular basis based on serological test results for several endemic diseases (4). Danish SPF farmers are reluctant to vaccinate their animals if they are disease-free due to: (1) the risk of using vaccine-like PRRS virus (PRRS type 2 was introduced in Denmark by live modified vaccine) (8) and (2) obtaining a disease-positive status based on serological tests (the existence of antibodies can be caused by a natural infection or vaccine usage) which will results in trade restrictions. Therefore, it is reasonable to assume that the number of vaccinated herds can be used as proxy of the number of infected farms.…”

Unweaving tangled mortality and antibiotic consumption data to detect disease outbreaks – Peaks, growths, and foresight in swine production

“…Changes in the percentage of herds generating alarms were analyzed from 4 months prior to 4 months after serologically observed changes in the disease status, because we assumed that subclinical and chronic cases would occur within this period, following the example of [46]. Moreover, the frequency of serological tests also depends on the herd type, varying from intervals of 4 weeks [47] up to 12 months, and seroconversion requires a minimum timespan (1–2 weeks for the IPMA test for PRRS [48]).…”

Development of a biosensor from aptamers for detection of the porcine reproductive and respiratory syndrome virus

“…Therefore, PRRS diagnosis platforms are based on the clinical symptoms and biochemical tests. The general symptoms of PRRS disease are respiratory problems, high levels of neonatal mortality, and reproductive failure in pigs of any age [ 1 8 9 10 11 12 ]. PRRS can be diagnosed using a wide range of serological tests for the detection of antibodies, as has been done during recent infections.…”