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1.
In a newly established farrow-to-finish farm (porcine reproductive and respiratory virus [PRRSV]-free, porcine circovirus type 2 [PCV-2]-infected), reproductive failure was seen seven months after population. The conception rate dropped from 89 to 51 per cent, and the abortion rate increased from 0.5 to 11 per cent. The following month, characteristic lesions of postweaning multisystemic wasting syndrome (PMWS) and elevated mortality were observed in weaned pigs. Laboratory examinations confirmed reproductive failure due to PRRSV and PMWS associated with apparent activation of the PCV-2 circulating in the farm. The herd was closed for replacement and a number of measures to improve hygiene, environmental conditions and feeding were applied. The abortion rate returned to preoutbreak levels four months after the beginning of the PRRS outbreak and the conception rate returned to normal four months later. Slower improvement was observed regarding the PMWS outbreak, with PMWS-related losses disappearing nine months after the detection of PMWS. Analysis of seroconversion profiles to PCV-2 and PRRSV during the outbreak and after its control indicated that while PRRSV was eliminated from sows and weaners by the control measures, the time of PCV-2 infection was unchanged and occurred at seven weeks of age during the PMWS outbreak as well as after its elimination. However, the elimination of PMWS from the herd coincided with increased levels of maternally derived antibodies to PCV-2 in one- to five-week-old pigs and faster serological responses to infection with PCV-2.  相似文献   

2.
A comparative serologic and virologic study was performed in pigs from 5 herds with postweaning multisystemic wasting syndrome (PMWS) and 2 herds without PMWS in Quebec. In each herd, 60 blood samples were collected at 4-wk intervals from pigs from 3 to 23 wk of age. The serum was evaluated for the presence of antibodies to porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV), as well as for the presence of nucleic acid of PCV2, PRRSV, and porcine parvovirus (PPV), by means of the polymerase chain reaction (PCR). Serologic profiles for PCV2 were very similar in 6 of the 7 herds, including the 2 without PMWS, and were characterized by a gradual decrease in antibody titres from 3 until 11 wk of age, followed by seroconversion at 15 wk, and high PCV2 antibody titres thereafter in all pigs. Only starting at 11 to 15 wk of age could PCV2 viremia be detected, except in 1 herd, in which clinical signs were observed at 6 to 7 wk of age. A PCV2 viremia could be detected within the same pigs for a minimum of 8 wk, and the virus could still be detected in 41% of the serum samples obtained at 23 wk of age. The antibody level did not appear to influence the occurrence of disease, since titres were similar in pigs in the herds with or without PMWS. Infection with PRRSV, as demonstrated by PCR and seroconversion, preceded that of PCV2 by at least 1 mo in both types of herd. Both PRRSV and PCV2 were detected in some pigs in 5 of the 7 herds, including 1 herd without PMWS. Porcine parvovirus could be detected in serum by PCR in 2 herds with PMWS after the onset of clinical signs and also in 1 herd without PMWS. Genomic analysis of PCV2 strains identified in the herds without PMWS indicated complete or very high homology (99.4% to 100%) with the PCV2 strains identified in 4 herds with PMWS. In our field study, the triggering of PMWS in the herds could not be linked to coinfection with either PRRSV or PPV or to the use of a specific immunostimulant, such as vaccines, or to particular genomic differences between the PCV2 strains identified.  相似文献   

3.
Postweaning multisystemic wasting syndrome (PMWS) is a worldwide emerging disease of weaned piglets. The objective of this review is to summarize the current knowledge regarding PMWS, its causative agent, mode of transmission, diagnostic techniques to detect PCV-2, the possible control measures, and the association of PMWS and PCV-2 with porcine dermatitis and nephropathy syndrome (PDNS). The causative agent of PMWS is porcine circovirus type 2 (PCV-2), however, not all pigs infected with PCV-2 develop the syndrome. PCV-2 is consistently associated with PMWS and PMWS is considered not to occur without it. Both the syndrome and the virus are not regarded as new. Co-factors that could activate PCV-2 to cause PMWS are considered. This enigmatic nature of both the syndrome and the virus is triggering a concern towards uncertainties of the viral transmission, its introduction in to the herd, effective tools of diagnosis, and control strategies.  相似文献   

4.
In two distinct commercial swine herds, poor weight gain and an increased number of animals showing wasting were observed among nursery and growing pigs. Cases of postweaning multisystemic wasting syndrome (PMWS) and infection with Haemophilus parasuis had been previously diagnosed in these herds. One growing wasted pig from each herd was necropsied and showed enlarged lymph nodes. Pseudomembranous material adhered to the dorsum of the tongue, soft and hard palate in case 1, and in case 2, fibrinous material was seen as whitish plaques on the oesophageal surface with hyperkeratosis of the non-glandular stomach. The main histological lesions in both cases were found in lymphoid tissues with a multifocal accentuated lymphohistiocytic infiltrate, areas of lymphoid depletion and intracytoplasmic inclusions in histiocytic cells in lymph nodes and Payer's patches. Focally, extensive ulceration was found in the stratified pavement epithelium of the tongue with necrosis and necrosuppurative infiltrate in case 1; in case 2, there was ulceration in the stomach with lymphohistiocytic infiltrate in the submucosa and ulceration in the mucosa of the oesophagus associated with yeast cells and pseudo-hyphae. Candida albicans was isolated from the oral cavity lesions. Immunohistochemistry of the lymph nodes was positive for porcine circovirus 2 (PCV2). The association between PMWS and mucocutaneous candidiasis reported here supports the potential immunosuppressive state of PMWS infected pigs.  相似文献   

5.
In this study, 60 pigs with clinical signs of post-weaning multisystemic wasting syndrome (PMWS) from 20 different pig herds and 180 control pigs (without clinical signs of PMWS) were examined to get more insights into the frequencies of porcine circovirus 2 infections and the presence of co-infections in pigs with and without clinical signs of PMWS in the Netherlands. Porcine circovirus type 2 was detected in 100% of the pigs with clinical signs of PMWS by virus isolation and/or PCR and in 50% of the pigs from PMWS-free herds. There was an association between the levels of infectious PCV2 and/or PCV2 DNA load and the severity of clinical signs as described for PMWS. A high variation in PCV2 antibody titres was found in the clinically affected pigs, and 27% of these pigs did not mount PCV2 antibody titres higher than 1:200. A concurrent infection of PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV) was found in at least 83% of the pigs with clinical signs of PMWS and in 35% of the pigs from PMWS-free herds. Co-infections of European- and American-type PRRSV were detected only in PMWS herds and in one control herd with a history of PMWS clinical signs.  相似文献   

6.
Postweaning multisystemic wasting syndrome (PMWS) is causally associated with porcine circovirus type 2 (PCV2) infection of pigs. PCV2 was first demonstrated in Swedish pigs in 1993, although the virus was almost certainly present in pigs in the country before that. Despite this, no signs of PMWS were observed in pigs of Sweden until the first outbreak was reported in 2003. The accumulated number of PMWS-affected herds have increased via 16 (2004) and 41 (2005) to 123 in December 2006. Of these herds, 30 (25%) have now been declared free from PMWS. However, a number of other herds have had individual pigs that have fulfilled the demands for PMWS at necropsy and 52 of these herds have been declared negative on herd basis after treatment for intestinal or respiratory diseases, and/or by correcting shortcomings in management of the herd including feed. Thus, individual cases of the disease have been observed in around 200 herds by the end of 2006 and PMWS is now regarded as an endemic disease in Sweden. The pig population of Sweden is geographically isolated, the density of pigs and the pathogen load in the country is low and the use of growth promoters (low dose antibiotics in feed) was prohibited in 1986. Additionally, the trade of animals in Sweden is organised in a restricted way. Because of these factors it is possible to conduct meaningful real-time studies on the transformation of PMWS in Sweden from being an exotic to an endemic disease in a three year time scale. Initially the PMWS cases were concentrated in the southern part of Sweden, but have gradually spread north. The PMWS-positive herds have, in general, had an effective production, but some management errors have constantly been observed in affected herds. Physical links between affected herds are often missing, and the data generated to date on the PMWS outbreaks in Sweden do not suggest an introduction of a new contagious microbe into the country that is responsible for the PMWS outbreaks, nor does PMWS appear to be spread via semen. In Sweden, intensity in rearing, disease preventing measures and immaturity of the piglets appear to be important as predisposing factors to PMWS and, as such, are discussed in this article.  相似文献   

7.
This study examined if pigs in a Porcine circovirus disease (PCVD)-affected herd (n = 100) had shed more Porcine circovirus-2 (PCV-2) in their feces than pigs in a PCVD-nonaffected herd (n = 101), and if differences in shedding among production stages within and between the herds existed. The PCV-2 shedding was quantified by real-time polymerase chain reaction. The highest median PCV-2 shedding was found in the nursery of the PCVD-affected herd and in the grower of the PCVD-nonaffected herd. The PCV-2 shedding was significantly higher in earlier stages (newly weaned, nursery, and pregrower) in the PCVD-affected herd (Wilcoxon rank sum; P < 0.001) compared with the PCVD-nonaffected herd. Porcine circovirus-2 DNA was not detected in a significant proportion of lactating sows (parity ≥ 3) in the PCVD-nonaffected herd (Fisher’s exact test; P = 0.001). The results of this study suggest there may be an association between the presence of PCV-2 in the feces of lactating sows and increased PCV-2 shedding in younger pigs.  相似文献   

8.
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9.
A retrospective cohort study of 116 British pig farms was undertaken to investigate the epidemiological risk factors associated with herd breakdowns with postweaning multisystemic wasting syndrome (PMWS). Farmers reported the PMWS status of their herd (case definition 1) and, where applicable, when the disease was first suspected and what they observed; they described a prolonged increase in mortality in six to 16-week-old pigs that was not attributable to any disease known to be on their farm. There was over 90 per cent agreement on the farmers' PMWS status between the farmers and their veterinarians. Approximately 70 per cent of the breakdowns were confirmed at the laboratory (case definition 2) except during the outbreak of foot-and-mouth disease (FMD) in 2001 when it was reduced to 30 per cent. Porcine circovirus type 2 antigen was detected in pigs examined postmortem (case definition 3) in approximately 90 per cent of the farms with increased mortality. The breakdowns occurred initially in the south of England and spread west and north, as well as locally in a radial pattern from the affected farms, and there was strong statistical evidence that there was non-random space-time clustering. The risk of herd breakdowns with PMWS was not constant; therefore, for each case definition, three survival models were developed with outcome variable time to breakdown of between January 2000 and January 2001, February 2001 to September 2001 (during FMD) or October 2001 to December 2003. Exposures with a bivariable significance of P<0.20 were tested in three multivariable Cox proportional hazard models. From January 2000 to January 2001 the risk of a herd breakdown with PMWS for definitions 1, 2 and 3 was greater for farms with 600 or more breeding sows, and for definitions 1 and 3 there was an increased risk associated with the purchase of replacement gilts rather than using homebred replacements. For definitions 1 and 3 the farms where the nearest pig farm had no breeding pigs were at greater risk of a breakdown than those where the nearest farm had breeding stock, as were the farms where visitors were not requested to avoid pigs for more than three days before visiting the farm during the FMD outbreak. From October 2001, the associated risks were identical for all three case definitions; farms were at greater risk when they had 600 or more breeding sows, if visitors had not avoided contact with pigs for more than three days before visiting the farm, and when there was a farm with PMWS less than five miles away. The affected farms were more likely to have disease associated with porcine parvovirus, porcine reproduction and respiratory syndrome virus, erysipelas, Escherichia coli and salmonella. These exposures were positively associated with large herds and the farm being close to other pig farms, but did not remain in the final models for breakdown with PMWS, indicating that such farms may be at greater risk of many infectious diseases.  相似文献   

10.
Potential risk factors for clinical signs of post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS) in pigs in the Netherlands were investigated in a matched case-control study using a questionnaire (personal interview). Eighty-two pig farmers were questioned about management, hygiene, husbandry systems, disease history, and preventive health care. In this study, 30 pig herds with (cases) and 30 pig herds without (controls) characteristic clinical signs of PMWS were compared. For PDNS, 11 pig herds with (cases) and II pig herds without (controls) characteristic clinical signs of PDNS were compared. Univariate analysis (P < 0.10) showed that the following occurred relatively more often in the PMWS case herds than in the control herds: 1) clinical signs of PDNS, porcine reproductive and respiratory syndrome (PRRS), porcine parvovirus (PPV) infections, meningitis, coccidiosis, and pre-weaning diarrhoea observed by the farmer; 2) vaccination against PRRS and mycoplasma; 3) non-optimal climatic conditions in the nursery rooms, a large variation in weaning age, a high occurrence of cross-fostering of piglets, a large number of sows with lactation problems, poor colostrum intake by piglets; and 4) (historical) use of breeding stock (including semen for artificial insemination) of Anglo-Saxon origin. In the final multivariate statistical model, one variable remained significantly associated with PMWS case herds, namely, the presence of clinical signs of PRRS (and/or the associated use of vaccination against PRRS). It should be noted that in almost all cases animals were vaccinated against PRRS because of clinical signs of PRRS that appeared a few months after the first occurrence of clinical signs of PMWS. This excludes PRRS vaccination as a primary factor in causing PMWS. Analysis of the PDNS case-control data showed comparable results with those of the PMWS study. In the final statistical model, the presence of clinical signs of PRRS (and/or the associated use of vaccination against PRRS) was significantly associated with PDNS case herds.  相似文献   

11.

Background

Despite that PMWS commonly affects pigs aged eight to sixteen weeks; most studies of PMWS have been conducted during the period before transfer to finishing herds. This study focused on PCV2 load and antibody dynamics in finishing herds with different PMWS status.

Methods

Sequentially collected blood samples from 40 pigs in each of two Swedish (A and B) and one Norwegian (C) finishing herds were analysed for serum PCV2-load and -antibodies and saliva cortisol. The two Swedish herds differed in PMWS status, despite receiving animals from the same sow pool (multi-site production). However, the PMWS-deemed herd (A) had previously also received pigs from the spot market. ResultsThe initial serum PCV2 load was similar in the two Swedish herds. In herd A, it peaked after two weeks in the finishing herd and a high number of the pigs had serum PCV2 levels above 107 per ml. The antibody titres increased continually with exception for the pigs that developed PMWS, that had initially low and then declining antibody levels. Pigs in the healthy herd B also expressed high titres of antibodies to PCV2 on arrival but remained at that level throughout the study whereas the viral load steadily decreased. No PCV2 antibodies and only low amounts of PCV2 DNA were detected in serum collected during the first five weeks in the PMWS-free herd C. Thereafter a peak in serum PCV2 load accompanied by an antibody response was recorded. PCV2 from the two Swedish herds grouped into genotype PCV2b whereas the Norwegian isolate grouped into PCV2a. Cortisol levels were lower in herd C than in herds A and B.

Conclusions

The most obvious difference between the Swedish finishing herds and the Norwegian herd was the time of infection with PCV2 in relation to the time of allocation, as well as the genotype of PCV2. Clinical PMWS was preceded by low levels of serum antibodies and a high load of PCV2 but did not develop in all such animals. It is notable that herd A became affected by PMWS after errors in management routine, emphasising the importance of proper hygiene and general disease-preventing measures.  相似文献   

12.
猪圆环病毒免疫学研究进展   总被引：1，自引：0，他引：1  
猪圆环病毒(PCV)在世界范围内广泛存在,可引起断奶仔猪多系统衰竭综合征(PMWS)、猪皮炎-肾病综合征(PDNS)和猪呼吸系统疾病症候群,给养猪业造成重大经济损失.已有研究表明,PCV-2感染和免疫刺激作用在PMWS发生中起关键作用,母源抗体对PMWS发生有被动保护作用,通过对初产母猪和经产母猪进行PCV-2免疫,增加母源性免疫和降低病毒血症的措施可以减少PMWS对仔猪死亡的影响.PCV-2疫苗现在已经在商业上应用,疫苗对PCV-2复制和PCVD的诱导增强作用似乎依赖于疫苗佐剂的类型和疫苗的接种时间.因此,基于有效的试验,在发生过PMWS感染的猪群,应该根据PCV-2感染的时间有目的地制定免疫接种方案,以控制或者减少PMWS的发生.  相似文献   

13.
A retrospective study was performed on natural cases of postweaning multisystemic wasting syndrome (PMWS), recorded from January 1999 to December 2000, to determine the prevalence, microscopic lesions, and other coexisting pathogens associated with PMWS. PMWS is diagnosed based on three criteria: the presence of clinical signs (retardation of growth), characteristic microscopic lesions (granulomatous inflammation and inclusion body), and the presence of porcine circovirus (PCV)-2 within these lesions. One hundred and thirty three (8.1%) of the 1634 pigs submitted from 1243 pig farms were diagnosed for PMWS. The affected pigs were from 25 to 120 days old, the majority (78 cases, 58.6%) being 60 to 80 days old. PMWS occurred each month during the two-year study period, but the incidence peaked in May (38 cases, 28.6%), followed by April (18 cases, 13.5%) and June (13 cases, 9.8%). The most consistent and characteristic lesions were multifocal, granulomatous inflammation in lymph nodes, liver and spleen, characterized by infiltration of epithelioid macrophages and multinucleated giant cells. The majority of cases (113 cases, 85.0%) was dual infection with other pathogens. The combination of PCV-2 and Hemophilus parasuis (43 cases, 32.3%) was shown to be the most prevalent followed by PCV-2 and porcine reproductive and respiratory syndrome virus (39 cases, 29.3%). The consistent presence of PCV-2, but lower prevalence of other viral and bacterial pathogens in all pigs examined with PMWS, has led to the speculation that PCV-2 is the etiological agent causing PMWS.  相似文献   

14.
The clinical syndrome Postweaning Multisystemic Wasting Syndrome (PMWS) in pigs has emerged globally during the last decade. In October 2001, the first pig herd diagnosed with PMWS was reported in Denmark, and since then the number of herds diagnosed with PMWS has increased markedly. The etiology of PMWS is not well understood, but increased knowledge of the causal factors is prerequisite for applying preventive interventions. In this study we described the temporal (time of diagnosis), spatial (location of herds) and spatio-temporal pattern of Danish pig herds diagnosed with PMWS during the first two years after the first herd was diagnosed, and we tested for spatial and spatio-temporal clustering using scan statistics. The study population consisted of pig herds that during the study period (October 2001-September 2003) performed diagnostic submissions to the two major veterinary diagnostic laboratories in Denmark (6724 herds). Of these, 277 herds were diagnosed with PMWS. Two statistically significant spatial clusters of herds diagnosed with PMWS were identified. These clusters included 11% and 8% of the study herds, respectively. Within these two clusters the relative risk for a herd to be diagnosed with PMWS was twice as high as expected. One statistically significant spatio-temporal cluster was identified between February and May 2002. We discuss different hypotheses that could explain why pig herds diagnosed with PMWS were clustered both spatially and spatio-temporally, and conclude that the results support the hypothesis that PMWS is caused by introduction of a new, unidentified, pathogen into the Danish pig production.  相似文献   

15.
Porcine circovirus-2 and concurrent infections in the field   总被引：27，自引：0，他引：27  
Porcine circovirus-2 (PCV-2) is the necessary cause of post-weaning multisystemic wasting syndrome (PMWS) in swine; however, a variety of co-factors, including other infectious agents, are thought to be necessary in the full expression of disease. Porcine parvovirus (PPV) was found in the inoculum used in the first experiments to reproduce PMWS in gnotobiotic swine. Retrospective and prospective studies in the field and laboratory have demonstrated PCV-2 can act synergistically with PPV to enhance the severity of PMWS. PCV-2 has been shown to play a role in the porcine infectious disease complex (PRDC). Other co-infecting agents with PCV-2 in the lung include, porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV) and Mycoplasma hyopneumoniae. Exposure of pregnant sows to PPV, PRRSV, or encephalomyocarditis virus may interact with PCV-2 infected foetuses. The severity of hepatic lesions in PCV-2 infected pigs may be enhanced by co-infection with agents such as swine hepatitis E virus and Aujezsky's disease virus. Additional studies are required to determine the mechanistic basis for the interaction of PCV-2 with other agents in the pathogenesis of the various clinical syndromes that have been associated with PCV-2 infection.  相似文献   

16.
Post-weaning Multisystemic Wasting Syndrome (PMWS) has been identified in most swine-producing countries worldwide. The disease has resulted in significant health challenges and economic damage to the swine industry. The aim of this study was to determine horizontal transmission of porcine circovirus type 2 (PCV2) and to examine viral dynamics in pigs in a controlled PMWS transmission study. In the study pigs from PMWS-affected herds and non-affected herds were permitted to have close contact (same pen), nose-to-nose contact (to pigs in neighbouring pens) or no physical contact (pen across the aisle and pens in other compartments). By DNA sequence analysis, eight variants of genotype PCV-2b were identified in the research facility. From the spread of these PCV2-variants it was concluded that PCV2 primarily infects through close contact and nose-to-nose contact. PCV2 genome sequences were obtained from selected pigs at arrival to the research facility and again when the same pigs developed PMWS. This analysis showed that pigs from PMWS-affected herds developed PMWS caused by the same variant of PCV2 as they carried when entering the research facility. In contrast, pigs from non-affected herds developed PMWS with PCV2-variants identified in pigs from PMWS-affected herds. This was probably connected to at least 103 higher mean serum-titer of PCV2 in pigs from PMWS-affected herds as compared to pigs from non-affected herds at the beginning of the transmission study. The study further showed that pigs able to control the PCV2 infection, as measured by the PCV2-titer in serum, recovered clinically (pigs from PMWS-affected herds) or stayed healthy (pigs from non-affected herds). Like this, pigs with a PCV2 titer below 5 × 108 copies/ml serum during the study period had a chance of recover from the PCV2 infection whereas pigs with PCV2 titers above 5 × 108 copies/ml serum at any time point generally died from PMWS.  相似文献   

17.
In order to control growing problems associated with porcine circovirus type 2 (PCV2) several vaccines for piglets or sows were introduced recently. An objective of the study was to compare an efficacy of three different vaccination protocols in the herd with acute postweaning multisystemic wasting syndrome (PMWS) outbreak affecting 3-month-old pigs. All of three applied protocols, namely vaccination of sows, piglets or sows and piglets with Circovac proved to be efficacious in controlling of PMWS. All production parameters significantly improved after vaccination. Obtained values were as good as before the outbreak or even better as in case of average daily weight gains. However, decreased mortality before weaning was recorded only after vaccination of sows while in groups where piglets were vaccinated significantly lower mortality in fourth month of life was observed. The impact of different protocols on different parameters suggests that they could be adopted in herds with different porcine circovirus associated problems.  相似文献   

18.
2005年-2006年,对广东省12个市（县／区）共40个猪场108头病例,应用病理学及病原检测方法对PCV-2感染情况进行调查。结果表明,PCV-2阳性44例,占总病例数的40．7％。从,10日龄到120日龄均有感染,以60日龄～70日龄多发。在PCV-2感染的病例中,混合感染占95．5％。以混合感染PRRSV（11例,25％）最多,混合感染APP次之（10例,22．7％）。另外,调查显示该病可全年发生,但5月份为发病高峰。  相似文献   

19.
The objective of this study was to evaluate the prevalence of infection with porcine circovirus-2 (PCV-2) and porcine reproductive and respiratory syndrome virus (PRRSV) through a longitudinal study in an integrated swine production system (7 farms) experiencing postweaning multisystemic wasting syndrome (PMWS). Risk factors for PCV-2 infection and for PCV-2 and PRRSV coinfection were also evaluated. Fifteen sows from each herd and 4 non-cross-fostered piglets from each sow were randomly selected at farrowing and ear-tagged at birth. Serum samples were analyzed for antibodies to PCV-2 and for detection of the PCV-2 and PRRSV genomes. Statistical analyses involved 2 approaches. The 1st approach characterized the dynamics of PCV-2 infection and their relationship with PRRSV infection. The 2nd approach analyzed the probability of being infected by PCV-2 or by both PCV-2 and PRRSV through a generalized linear mixed model incorporating sow and farm characteristics. At the 1st sampling time (1 wk of age), there was a significant relationship between sow PCV-2 infection and piglet PCV-2 infection (P < 0.0001). The risk of PCV-2 and PRRSV coinfection was 1.85 times greater in piglets from a sow with low titers of PCV-2 antibodies than in piglets from sows with medium to high titers (P = 0.03) and was 2.54, 2.40, and 2.02 times greater, respectively, in piglets from primiparous sows, PCV-2-infected sows, and farms in an area of high pig density than in piglets from sows of higher parity (P = 0.004), noninfected sows (P = 0.04), and farms in a low-density area (P = 0.09).  相似文献   

20.
Postweaning wasting is a major worldwide problem in pig production, particularly with respect to the disease termed postweaning multisystemic wasting syndrome (PMWS). In addition to wasting, PMWS symptoms include respiratory distress, diarrhoea, pallor and occasional cases of jaundice. The causative agent is porcine circovirus type 2 (PCV-2). The objective of the present study was to determine the significance of PMWS and similar conditions in Switzerland. A total of 72 weaned piglets from 26 farms showing wasting were examined for the presence of PCV-2 by immunohistochemical and histological analysis and 57 piglets from 21 farms were examined serologically. Possible causes for wasting other than PCV-2 were investigated by macroscopic, histological and bacteriological methods. PCV-2 antigen was identified immunohistochemically in the lymphatic organs in 11 of these 72 piglets. However, only 4 animals showed histological changes typical of PMWS. PCV-2 antibodies were found in 70% of the piglets. Piglets with wasting syndrome not associated with PCV-2 infection suffered from conditions including porcine proliferative enteropathy, gastric ulcers, polyserositis and polyarthritis. The most frequent condition was chronic enteritis not associated to circovirus infection. The results from the serological analyses indicate a wide distribution of PCV-2 in the Swiss pig population. However, confirmed cases of PMWS were rare in the investigated piglets.  相似文献   

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