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1.
Objective To report the occurrence and pathology of porcine circovirus type 2 (PCV2)‐associated disease (PCVAD) of postweaning pigs in two Australian pig herds. Methods Mortality data from two commercial piggeries that experienced higher than normal postweaning illthrift and mortalities were examined. Gross and histopathological examinations were performed on the index cases, and at weekly intervals thereafter for a period of 10 weeks. Specimens were submitted to the laboratory for routine diagnostic testing and for exclusion of porcine reproductive and respiratory syndrome virus (PRRSV). The genomes of two strains of PCV2 isolated during testing were sequenced. Results Mortality rates in weaned, 5–12‐week‐old pigs spiked significantly during mid to late 2007. This increase in the mortalities was mainly attributed to salmonella‐associated diarrhoea and illthrift. Salmonellosis was diagnosed in 73/110 cases inclusive of both piggeries. Many pigs also had chronic granulomatous lymphadenitis and diffuse histiocytic interstitial pneumonia consistent with PCVAD and associated with varying amounts of PCV2 antigen and inclusion bodies. All samples tested for PRRSV were negative. Sequence analysis of the PCV2 isolates showed strain differences between piggeries. Conclusion This report describes the first outbreaks of PCVAD in growing pigs in Western Australia (WA) and describes lesions not previously seen in this laboratory. It also describes the first isolation of a PCV2 group 1 virus in WA associated with PCVAD. Although the outbreaks of PCVAD occurred with concurrent salmonellosis, the two diseases were unrelated. Neither of the outbreaks met the Australian case definition for the diagnosis of postweaning multisystemic wasting syndrome.  相似文献   

2.
Two types of transmission experiments were performed to estimate the basic reproduction ratio R(0), indicating the level of encephalomyocarditis virus (EMCV) transmission among pigs. In a first experimental set-up with nine separate pairs, one randomly chosen piglet per pair was inoculated with a Belgian (myocardial) EMCV strain (B279/95, 10(3)TCID(50)/ml oronasally) and placed back into the pen. In the second experiment with two separate groups of five piglets, two piglets in each group were inoculated at the start. During the experiments, viraemia in blood and excretions was measured as well as the serological response against EMCV antigen. After death or euthanasia, the piglets were checked for heart lesions and virus isolation was done on various tissues. In both the experiments, the majority of the inoculated piglets either died with typical heart lesions (five out of nine and three out of four resp.), or produced high levels of neutralising antibody. EMC virus was isolated from the hearts of all piglets that died during either one of the experiments. The pairwise experiment revealed a point estimate for R(0) of 2.0 (95% confidence interval (CI)=0.37-10.74), while the group experiment resulted in a R(0)-value of 0.71 (95% CI=0.08-4.93). Combining the information from both experiments results in an estimate for R(0) of 1.24 (95% CI=0.39-4.35). Since R(0) has values around the threshold value of 1, the spread of EMCV due to contacts between pigs will in most cases be limited, but due to chance processes may lead to large outbreaks as well.  相似文献   

3.
Epidemiology and control of Menangle virus in pigs   总被引：6，自引：0，他引：6  
OBJECTIVE: To describe the epidemiology and eradication of Menangle virus infection in pigs. DESIGN: Field observations and interventions, structured and unstructured serological surveys, prospective and cross-sectional serological studies and laboratory investigations. PROCEDURE: Serum samples were collected from pigs at a 2600-sow intensive piggery in New South Wales that experienced an outbreak of reproductive disease in 1997. Serum samples were also collected from piggeries that received pigs from or supplied pigs to the affected piggery and from other piggeries in Australia. Serum and tissue samples were collected from pigs at piggeries experiencing reproductive disease in New South Wales. Sera and faeces were collected from grey-headed flying foxes (Pteropus poliocephalus) in the region of the affected piggery. Serum samples were tested for neutralising antibodies against Menangle virus. Virus isolation was attempted from faeces. RESULTS: Following the outbreak of reproductive disease, sera from 96% of adult pigs at the affected piggery, including sows that produced affected litters, contained neutralising antibodies against Menangle virus. Neutralising antibodies were also detected in sera from 88% of finisher pigs at two piggeries receiving weaned pigs from the affected piggery. No evidence of Menangle virus infection was found in other piggeries in Australia. In cross-sectional studies at the affected piggery, colostral antibodies were undetectable in most pigs by 14 to 15 weeks of age. By slaughter age or entry to the breeding herd, 95% of pigs developed high antibody titres (> or = 128) against Menangle virus in the virus neutralisation test. Menangle virus was eradicated from the affected piggery following a program of serological testing and segregation. Neutralising antibodies against Menangle virus were also detected in P poliocephalus from two colonies in the vicinity of the affected piggery. Two piggery workers were infected with Menangle virus. There was no evidence of infection in cattle, sheep, birds, rodents, feral cats and a dog at the affected piggery. CONCLUSIONS: Serological evidence of infection with Menangle virus was detected in pigs at a piggery that had experienced reproductive disease, in pigs at two associated piggeries and in fruit bats in the region of the piggery. Two humans were infected. The mode of transmission between pigs is unknown, but spread by faecal or urinary excretion is postulated. This virus can be eradicated by the segregation of pigs into discrete age groups.  相似文献   

4.
规模化猪场脑心肌炎病毒感染的血清学调查   总被引：17，自引：0，他引：17  
脑心肌炎病毒(EMCV)可引起猪的脑炎、心肌炎和母猪繁殖障碍,该病已在世界上多个国家暴发和流行。我国对EMCV及其所致疾病的研究工作还处于起步阶段,为了揭示EMCV在我国规模化猪场的感染情况,我们应用酶联免疫吸附试验(ELISA)对2005-2006年间采集自全国13个省市46个规模化猪场的3250份血清样本进行了EMCV抗体检测,结果显示,各省阳性率在39.64%~90%之间,平均抗体阳性率为72%,监测的46个猪场都存在EMCV感染,猪场感染阳性率为100%;对不同生长阶段猪群检测结果表明,EMCV抗体阳性率随猪龄的增长而升高,且不同生长阶段猪抗体阳性率差异极显著;成年公猪的抗体阳性率高于成年母猪。本项调查表明,我国规模化猪场已经普遍感染EMCV,这应引起我国养猪业警惕,并做好该病的综合防控。  相似文献   

5.
The pathogenicity of two porcine encephalomyocarditis virus (EMCV) isolates for sows in gestation and young piglets was studied. One virus originated from a case of reproductive failure in pigs in Belgium and the other from a case of acute myocarditis in pigs in Greece. Sows in the mid-gestation period and one- to two-month old piglets were inoculated with each isolate. The molecular relationship between both isolates was studied by determining the nucleotide sequence located across the junction of the 1C and 1D capsid-coding genes. Antigenic analysis was performed using a panel of 35 monoclonal antibodies raised against an Italian field isolate of EMCV. All three approaches revealed differences between both isolates and also confirmed that there was no link between the two outbreaks of disease.  相似文献   

6.
The results of investigations of 11 outbreaks of foot-and-mouth disease in villages in northern Thailand are described. The causative virus was Asia in one in seven outbreaks, Type O in two outbreaks and unknown in two outbreaks. The most probable sources of the outbreaks were co-mingling of cattle and/or buffalo with livestock from an infected neighbouring village (four) and recent introductions of infected cattle from a public livestock market (two) while the probable source could not be determined in five outbreaks. Attack rates in cattle and buffalo ranged from 0.28% to 50.9% but no pigs became sick during any of the outbreaks. Most outbreaks lasted 4 weeks or less. Adult cattle and buffalo were at higher risk of becoming a case when compared with work cattle. Beef cattle were at higher risk than buffalo and adult cattle and buffalo were at higher risk than calves less than 1 year of age. There was significant clustering of cases within households. Serological investigations indicated that many unaffected animals were probably not exposed to virus during the outbreaks. We concluded that close contact between animals was the main method of spread and that differences in attack rates between animal classes reflected differences in animal management. We further concluded that simple quarantine of early cases during outbreaks is likely to be effective in reducing spread within and between villages.  相似文献   

7.
The pathogenesis of encephalomyocarditis (EMC) due to the EMC virus (EMCV) was studied in 24 piglets oro-nasally infected with the field isolate B279/95. Two pigs were kept as negative controls and were euthanised at hour 0. The remaining 24 were euthanised every 6 h up to 78-h post infection (hpi). Virus isolation, histological examination and EMCV immunodetection were performed on the spleen, intestine, pancreas, liver, kidneys, heart, lungs, lymph nodes, tonsils and brain. EMCV was isolated at 6-hpi from the intestine and lymph nodes and at 12-hpi from the heart. From 6 to 12-hpi, scattered degenerate myocardiocytes were immunolabelled. Subsequently, myocarditis developed and progressively worsened. Immunopositive reaction in tonsil macrophages, observed in the early stage of infection (6-hpi), suggests that tonsils are the portal of entry, and by mean of wandering macrophages the EMC virus is then distributed through the body. Afterwards, EMCV-B279/95 replicates intensively in the cytoplasm of myocardiocytes and the acute myocarditis is strictly related to the tropism of these cells. Four pigs died spontaneously. In three animals no post mortem lesions or virus were isolated/detected, although all of them showed mild myocarditis. The experimental infection with EMCV B279/95 indicates: (i) the experimental protocol mimics the individual variability observed in natural disease, (ii) tonsils are the portal of entry of infection and the heart is the target organ, (iii) EMCV provides a valuable animal model for comparative studies on progressive viral myocarditis.  相似文献   

8.
Serological examination of 177 strains of haemolytic Escherichia coil from pigs from 95 piggeries showed that 50 isolates from 28 piggeries were agglutinated by serums prepared against 0141:K85ab, 45 from 20 piggeries by 0141:K85ac, 32 isolates from 19 piggeries by 08 and four isolates from two piggeries by 0139:K82. Forty-six strains from 26 piggeries were unclassified. Ninety strains were isolated from intestine and/or mesenteric lymph nodes and 87 from other organs. Of the 95 outbreaks associated with haemolytic E. coli, 41 were diagnosed as oedema disease, 40 as coli-enteritis and the remainder were miscellaneous conditions. The clinical and pathological features of outbreaks associated with colibacillosis and septicaemic salmonellosis were compared and discussed.  相似文献   

9.
Ten multiparous sows were inoculated between 46 and 50 days of gestation with a fetal swine isolate of encephalomyocarditis virus (EMCV) to investigate the ability of the virus to cause transplacental infection and fetal death. Four sows (group 1) were inoculated IM with EMCV MN-25 that had been passaged 4 times on baby hamster kidney-21 line cell monolayers. Two sows were euthanatized at postinoculation (PI) day 23, and the other 2 sows at PI day 44. An additional 6 sows (group 2) were inoculated IM with the same virus that had been passaged 5 additional times in pigs. Two sows were euthanatized at 14 days, and the remaining 4 sows at PI day 28. Clinical signs were not observed in any of the sows, whereas all sows seroconverted to EMCV. In group 1, only 2 of 50 fetuses were mummified. Virus was not recovered, although EMCV antibodies were detected in the 2 mummified fetuses. In group 2, the 2 sows that were euthanatized at PI day 14 had 26 normal fetuses and there was no evidence of fetal infection. However, in the 4 sows euthanatized at PI day 28, 20 of 48 fetuses were mummified, hemorrhagic, or edematous. Encephalomyocarditis virus was recovered from 21 of 48 fetuses. Transplacental infection and fetal deaths in pregnant sows was achieved following infection with EMCV passaged in pigs.  相似文献   

10.
Two experiments were performed to compare the severity of encephalomyocarditis virus (EMCV) infection in pigs. The pigs were challenged with the Greek myocardial strain, at different ages and with different doses. In the first experiment, nineteen susceptible pigs, 40 days old, were divided into three groups and were experimentally infected with 10(6) TCID(50), 10(4) TCID(50) or 10(2) TCID(50) of the Greek EMCV strain. In the second experiment, 10 susceptible pigs, of either 20 or 105 days, were divided into two groups according to age and were experimentally infected with 10(6) TCID(50) of the Greek EMCV strain. In addition, five piglets, each one the same age as its experimental group, were used as uninfected controls. No clinical signs were observed after infection, except a transient temperature rise in some pigs. Another important observation was the difference in mortality between groups. The survival rate of the 40-day-old pigs was inversely related to the viral dose. In these pigs, a positive association between the viral dose and the severity of macroscopical and histopathological lesions of the heart was also evident. Viral isolations from various organs of the challenged 40-day-old pigs increased with the increasing dose level. When challenged with 10(6) TCID(50) of EMCV, there was no difference in the fatality rate of the 20- and 40-day-old pigs, but none of the 105-day-old pigs died. The severity of the macroscopical and the histopathological heart lesions was inversely related to the age of the pigs. Furthermore, viral isolations from the various organs were higher in 20- and 40-day-old pigs than in the older ones. In 40-day-old pigs, neutralizing antibodies linearly increased as the dose increased. These antibodies were consistently lower in 20-day-old pigs. Viraemia, and nasal and faecal excretions were detected in all groups and lasted 1-3 days, except for the 105-day-old pigs whose symptoms lasted for an additional day.  相似文献   

11.

The present study describes assessment of sanitary measures in piggeries of Benue State, Nigeria, to identify the risk factors of African swine fever. Questionnaires were distributed to 74 respondents consisting of piggery owners and attendants in different piggeries across 12 local government areas (LGAs) to collect data for this study. Sanitary measures in piggeries were observed to be generally very poor, though respondents admitted being aware of ASF. Piggeries located within 1-km radius of a slaughter slab (OR?=?9.2, 95% CI 3.0–28.8; p?<?0.0001) and piggeries near refuse dump sites (OR?=?3.0, 95% CI 1.0–9.5; p?<?0.05) showed higher chances of African swine fever virus (ASFV) infection, while piggeries where farm workers wear their work clothes outside of the piggery premises (OR?=?0.2, 95% CI 0.1–0.7; p?<?0.01) indicate less chances of infection but had a significantly associated p value thus were identified as potential risk factors. The study concluded that pigs in Benue State are still at risk of an ASF outbreak. Proper sanitary and hygienic practices are advocated and emphasized in piggeries, while routine surveillance for African swine fever virus antibodies in pigs in Benue State is strongly recommended to provide a reliable reference database to plan for the prevention of any devastating ASF outbreak.

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12.
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13.
Pigs can harbour a variety of viruses in their gastrointestinal tract. Some of them are closely related to human viruses and are therefore suspected to have a zoonotic potential. Only little is known about the presence of those viruses in pigs at slaughter. However, by contamination of meat with zoonotic viruses during the slaughtering process, food-borne transmission to humans may be possible. Here we analyzed 120 faecal samples of pigs at slaughter from 3 different geographical regions of Germany for the presence of astrovirus (AstV), encephalomyocarditis virus (EMCV), hepatitis E virus (HEV), norovirus genogroup II (NoV GII) and group A rotavirus (GARV). Using real-time RT-PCR, the most frequently detected virus was AstV, which was present in 20.8% of the samples, followed by NoV GII with a detection rate of 14.2%. EMCV, HEV and GARV were found only occasionally with detection rates of 4.2%, 2.5% and 0.8%, respectively. Analyses of partial genome sequences of the viruses indicated that the detected AstV and NoV GII mainly represented typical pig virus strains, which have not been detected in humans so far. However, the GARV and HEV strains were more closely related to human strains. The results indicate that enteric viruses, some of them with zoonotic potential, are present in pig faeces at slaughter. Application of good hygiene practice is necessary to minimize the risk of introducing these viruses into the food and to prevent virus transmission to highly exposed persons such as slaughterers and veterinarians.  相似文献   

14.
In 1991 EMCV was isolated for the first time in Belgium from the offspring of a sow with reproductive failure. From August 1995 until December 1996, EMCV was diagnosed in 154 Belgian pig holdings in association with myocardial failure and sudden death in fatteners and suckling piglets or with reproductive failure in sows. To clarify some epidemiological aspects 3 EMCV isolates characteristic for the different clinical pictures and outbreaks were studied. Field observations and animal experiments indicated that the pathogenicity induced by each isolate is specific for one age category and that the spread of the virus is limited. The presented data also suggest that rodents may play a role in the transmission of EMCV but that pig-to-pig transmission is at least as important. Molecular analysis of two separate regions on the genomes of the respective EMCV isolates showed that the 1995-96 EMCV epizootic in Belgium was due to a new virus introduction. Furthermore, the VP1 coding gene is proposed as a marker of virulence.  相似文献   

15.
Factors affecting mortality in finishing pigs   总被引：2，自引：0，他引：2  
Two groups of finishing pigs at a test station were studied to test the effect of initial weight, weight change in the 1st week, age, breed, and distance the pig was transported on mortality. Total mortality was 5.3% in 1 group and 6.3% in the other group. Specific causes of death were pneumonia (24.7%), gastric ulceration (14.0%), enteritis (6.4%), trauma (4.3%), gastrointestinal displacement (4.3%), rectal stricture (3.2%), porcine stress syndrome (3.2%), and brain abscess (2.2%). Other categories for cause of death were miscellaneous (6.5%), and undiagnosed (31.2%). More pigs died in the last 6 weeks of the 18-week finishing period than in the 1st 6 weeks (P less than 0.05). Death rates were not significantly different between pigs that lost weight and pigs that maintained or gained weight during the 1st week after arrival at the test station. The mean transportation distance to the test station was not significantly different between pigs that died and pigs that survived. Transportation distance was not correlated with mean daily gain. The death rate was significantly (P less than 0.03) higher for Yorkshire pigs than for crossbred, Poland China, Hampshire, and Duroc pigs, and it was significantly (P less than 0.01) higher for Berkshire, Spot, and Chester White pigs than for Hampshire and Duroc pigs.  相似文献   

16.
The housing, management and internal parasite control practices used in piggeries in Western Australia was surveyed by interviewing the owner/manager of 100 randomly selected piggeries. At the time of the interview 20 faecal samples were collected from pigs and examined for evidence of internal parasites. Most herds (80%) in which anthelmintics were used, had evidence of nematode infection. Some pig producers were using an anthelmintic that was ineffective against nematode species present while some herds had nematodes that should have been controlled by the anthelmintic being used. Prevalence of nematode infection was higher in pigs run in paddocks than in pigs housed intensively. Washing sows prior to farrowing was associated with a lower prevalence of nematode infection. The findings suggested that pig producers should ensure that the anthelmintic used is effective against the nematodes present in their pigs. It was concluded that administering anthelmintics as a single dose in the feed may not be the most effective method of deworming pigs.  相似文献   

17.
To evaluate the relative importance of the various enteropathogens causing neonatal diarrhea in Quebec farrowing operations, observations were made on 749 diarrheic pigs from 325 outbreaks of diarrhea. They were one to 15 days of age, and were obtained alive for necropsy generally within 48 hours of the onset of diarrhea. Some pigs were from severe, explosive outbreaks of diarrhea with high morbidity and mortality rates, while others were from herds with chronic neonatal diarrhea with lower morbidity and mortality rates. A combination of bacteriological, virological and histological methods were used to study the pigs.

Viruses were incriminated in 60%, bacteria in 23% and coccidia in 15.3% of the 325 diarrhea outbreaks. Transmissible gastroenteritis virus was by far the most common enteropathogen with a prevalence of 52%; rotavirus was implicated in 9.2% of the outbreaks while adenovirus was incriminated in 0.30% of the outbreaks. Enterotoxigenic Escherichia coli were involved in 22.4% of the cases while Clostridium perfringens type C was an occasional finding. Coccidia involved in our herds were identified as Isospora suis. The disease was attributed to infection with a single etiologic agent in 590 diarrheic pigs (78%) while combinations of agents were present in only 90 (12%).

The age-specific occurrence of the various enteropathogens was evaluated. Transmissible gastroenteritis virus was the most common enteropathogen in all age groups. Colibacillosis was common in pigs which became diarrheic under five days of age; in this age group, the enterotoxigenic E. coli were frequently found alone, but were usually combined with other agents in older pigs. The prevalence of coccidia was high in pigs which became diarrheic between five and 15 days of age. Rotavirus infection was common in diarrheic pigs older than ten days of age. Although individual baby pigs were commonly infected with a single enteropathogen, it was very common to see more than one agent involved in an outbreak of diarrhea, particularly when pigs of different ages were affected.

Observations on the occurrence of the enteropathogens according to the seasons were also made. Occurrence of transmissible gastroenteritis was throughout the year with the highest prevalence during the fall, winter and spring months. Colibacillosis and coccidiosis were more common in the summer, fall and early winter months with the lowest prevalence in the spring months.

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18.
Samples of serum from 76 gilts, 1440 sows, 1473 piglets and 3093 finishing pigs from 96 farrow-to-finish herds were tested for antibodies to encephalomyocarditis virus (EMCV) in microtitre serum neutralisation tests employing two strains of virus, one associated with myocarditis and the other with reproductive failure. The total seroprevalence of EMCV infection was 2.48 per cent. There was no significant difference between the seroprevalence of the reproductive failure strain (1.6 per cent) and the myocardial strain (1.85 per cent). The seroprevalence was higher in the gilts (6.57 per cent) and sows (5.13 per cent) than in the piglets (1 per cent) and finishing pigs (1.84 per cent), and the highest titres were observed in the sows (1:540) and finishing pigs (1:640). In the gilts, the difference in seroprevalence between the reproductive failure strain (3.95 per cent) and the myocardial strain (5.33 per cent) was wider than in the other groups.  相似文献   

19.
Encephalomyocarditis virus (EMCV) outbreaks are rare in southern Africa. Only two have been reported to date from South Africa, both coinciding with rodent irruptions. The first outbreak manifested as acute myocarditis in pigs in 1979, whilst the second, occurring from 1993 to 1994, was linked to the deaths of 64 free-ranging adult African elephants (Loxodonta africana). The P1 genome region, inclusive of the flanking leader (L) and 2A genes, of three South African isolates, one from swine and two from elephants, was characterised by PCR amplification and sequencing of up to 11 overlapping fragments. In addition to the resulting 3329 nucleotide dataset, the 3D region that is widely used in molecular epidemiology studies, was characterised, and three datasets (P1, VP1/3 and 3D), complemented with available homologous EMCV data, were compiled for analyses. Phylogenetic inferences revealed the near-identical elephant outbreak strains to be most closely related to a mengovirus from rhesus macaques (Macaca mulatta) in Uganda, differing from the latter by between 11% (3D) and 15% (VP3/1). The South African pig isolate differed by 4% (3D) and 11% (VP3/1) from available European and Asian pig virus sequences. This study confirms the presence of two genetically distinct EMCV lineages recovered from sporadic outbreaks in wild and domestic hosts in southern Africa, and provides valuable baseline data for future outbreak eventualities in the sub-region.  相似文献   

20.
Between September 1982 and March 1984, 101 Western Australian piggeries with 15 or more sows were surveyed to determine the prevalence of internal parasites and examine the relationship between parasitism and management practices. Faecal samples were collected from 20 pigs in 4 age groups in randomly selected piggeries, and examined for the presence of eggs of helminth parasites and protozoan cysts. Evidence of nematode parasites was found in 79% of piggeries. Sows were more commonly affected than other classes of pigs with worm eggs being found in 68% of herds. Oesophagostomum spp was the most prevalent worm species, being found in pigs from 65% of piggeries and in sows in 60% of herds. Ascaris suum was the most common species of worm found in growing pigs. There was no evidence of infection with either Metastrongylus spp or Strongyloides spp in any of the herds sampled. Oocysts of coccidia were found in pigs from 56% of piggeries and Balantidium coli cysts were detected in pigs from 42% of piggeries sampled.  相似文献   

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