Epidemiological Investigation Of Pseudorabies In Pigs In Some Pig Farms Of Heilongjiang Province

Pseudorabies (PR) is an acute infectious disease which is caused by pseudorabies virus (PRV). PRV cause diseases in a variety of animals and lead to severe economic losses. In recent years, the disease has spread across China and posed great impact on the swine industry. The swine industry is one of the major components of Heilognjiang’s animal husbandry. Important infectious diseases are still the most important factors which affect pig’s health and food quality. However, the current status of swine pseudorabies in pigs in Heilongjiang is not very clear, so it is necessary to conduct epidemiological survey to get data and information of the disease, which is important to make decisions on disease prevention and control.In this study, the survey program was designed based on epidemiological principles for estimate the herd prevalence of swine pseudorabies and identify potential risk factors.Two-stage sampling method was used in the study:at farm level, the farms were randomly selected from a sampling framework; at pig level, pigs were sampled in each farm to prove that at least one positive pig was test at95%confidence interval. Within a farm, only sows and piglets were sampled using a risk-based strategy. A questionnaire was filled in each farm during sampling for analyzing potential risk factors.In total of72pig farms from10cities involved into the survey and72questionnaires were filled out.1237serum samples (653from weaned piglet,584from sows) were collected and tested by ELISA for detect PRV gE protein antibodies. gE protein antibody positive samples were89/1237and the prevalence was7.2%(95%CI:6.5,7.9). The number of pig farms which have at least one positive sample were31, the farm prevalence was43.1%(95%CI:37.4,48.8). The herd prevalence in breeding farms (100.0%,95%CI:100.0,100.0) was highest. Risk factors analysis results showed that the increase of risk in pig farms infect with PR was close related to none own breeding and rearing (RR=1.8,95%CI:1.0,3.5). The risk of not own breeding and rearing is1.8times to own breeding and rearing.1225nasal swabs samples (649from weaned piglet,576from sows) were sampled and separated. PCR positive samples were49/1225and the prevalence was4.0%(95%CI:1.3,6.7). The number of pig farms which have at least one positive sample were6, the farm prevalence was8.3%(95%CI:5.1,11.5).17strains pseudorabies virus which PCR results was positive were selected to sequence and analyze the homology with the pandemic strain of domestic and abroad. The result is that genetic of 15sequences close to the domestic epidemic strains and two strains close to foreign isolates strains.We observed positive swab samples which identified by PCR and sequence with electron microscopy and the virus particle and its capsule was cleared be seen.