Simulation of the economic impact of proliferative enteritis on pig production in Australia

The economic impact of proliferative enteritis (PE) on an ‘average’ pig farm was calculated using the AUSPIG decision support system. Inputs were modelled on actual cases of PE, in which affected herds suffered from depressed growth rate, decreased feed efficiency and stock losses. The costs associated with non-haemorrhagic PE and proliferative haemorrhagic enteropathy ranged from $15/sow/yr to $141/sow/yr, respectively, depending on the clinical severity of the disease, incidence of infection and the type of medication strategy used to treat and control the disease.     

Outbreaks of proliferative haemorrhagic enteropathy on two pig farms

SUMMARY Clinical signs of proliferative haemorrhagic enteropathy (PHE) including anaemia, dysentery and sudden death were observed in finisher pigs and young breeding stock on 2 farms. On farm A, PHE occurred 12 months after repopulation of the farm. Other outbreaks of PHE occurred after the withdrawal of therapeutic concentrations of in-feed antibacterial agents (farm A), or after monensin sodium (100 g/t) replaced olaquindox (100 g/t) in feed (farm B). The outbreaks, the possible sources of contamination and the role of antibacterial feed additives in the treatment and control of PHE are described.     

Monitored control programme for proliferative enteropathy on British pig farms

The effect of control programmes on proliferative enteropathy and its causative agent (Lawsonia intracellularis) was investigated on four farrow-to-finish pig farms in Britain. Faeces samples from groups of boars and gilts in breeding programmes, and from preweaning and postweaning pigs were monitored prospectively every month for six months by a L intracellularis-specific polymerase chain reaction (PCR). On one farm with 150 sows, an outbreak of acute proliferative enteropathy in boars and gilts was controlled clinically by the use of tiamulin and chlortetracycline. The percentage of detectable PCR-positive pigs decreased from between 50 to 70 per cent to zero in the treated pigs and their progeny less than 14 weeks old, but clinical signs of the disease and PCR-positive pigs were detected in some 14-week-old pigs derived from the treated groups. On another farm with 160 sows, an outbreak of chronic proliferative enteropathy in six-week-old pigs (23 to 26 per cent PCR-positive) was controlled by the use of oral tylosin phosphate. Faeces samples from the medicated pigs on this farm remained PCR-negative during the study period, whereas samples from unmedicated control pigs showed that the infection persisted in some pigs for at least six weeks. The two other monitored farms remained PCR-negative and clinically negative for the disease during the study period. These farms treated the pigs regularly with oral chlortetracycline.     

猪源多杀性巴氏杆菌的病原流行病学及其毒力特性

2009-2013年间,采用病原菌的形态学观察、生化鉴定和PCR鉴定,从河南及其周边省份1 914份有肺炎等症状猪的肺脏等病料组织中分离鉴定出142株多杀性巴氏杆菌(总分离率为7.4%),其中A型69株,占48.6%;D型70株,占49.3%;3株不能定型;没有发现B、E和F型。2009-2013年间,多杀性巴氏杆菌不同年份的分离率为6.0%~10.6%,其中2012年显著偏高(P0.01)。另外发现其分离率具有明显的季节性,其中6和12月份最高。多杀性巴氏杆菌最常见的共感染菌依次是链球菌(50.5%)、副猪嗜血杆菌(41.1%)、大肠杆菌(29.5%)、支气管败血波氏杆菌(14.7%)和沙门菌(10.5%)。小鼠毒力试验结果表明,多杀性巴氏杆菌血清A型菌株毒力普遍较强,而D型毒力普遍较弱。但是,A型菌株也有毒力较弱的菌株,另外,在D型菌株中发现了一株毒力很弱的菌株PM-18,其LD50在4.8×107 CFU以上,该菌株是否能作为天然弱毒疫苗菌株值得进一步研究。     

Prevalence of Salmonella spp. on Canadian pig farms using liquid or dry-feeding

The objective of this study was to determine whether the shedding and antibody titre to Salmonella was lower for pig herds provided liquid-feed compared to those on traditional dry rations. Twenty liquid-feeding farms and 61 dry-feeding farms were selected. The amount of antibodies to Salmonella in sera from 15 finisher pigs on each of 80 Ontario swine farms was analyzed by means of enzyme-linked immunosorbent assay (ELISA). In addition, the presence of Salmonella on the 20 liquid-feeding farms and 21 of the dry-feeding farms was assessed by culture of 15 fecal samples taken directly from finisher pigs and five pooled pen-fecal samples at each farm.

A cut-off of OD% 10 was used. The Salmonella sero-prevalence differed between the two groups of farms. At least one pig tested sero-positive on 98% of the dry-feeding farms and 84% of the liquid-feeding farms (P < 0.05). A multi-variable mixed linear regression model with the farm as a random variable and farm factors as the fixed effects was fitted. Crude optical density (OD) of the individual pig was considered as the continuous dependent variable. Dry-feeding and antimicrobial daily usage was associated with crude OD (P < 0.05). In addition, crude OD increased with increasing herd size (P < 0.05).

Salmonella was isolated from 25 out of 420 fecal samples (6%) from dry-feeding farms compared to three out of 400 samples (0.8%) from liquid-feeding farms. Eight of the dry-feeding farms (38%) tested positive compared to only three of the liquid-feeding farms (15%). Salmonella was also recovered from the pen environment on five dry-feeding farms but were not isolated from the facilities using liquid-feeding. Salmonella Typhimurium was isolated from four farms in the dry-feed group and on one farm with liquid-feeding. The one S. Typhimurium isolate from the liquid-feeding farm exhibited no antimicrobial resistance, but those from dry-feeding farms were resistant to four or more antimicrobial agents. The results of the logistic regression, with farm as a random effect showed that dry-feeding [OR = 2.7 (1.1–15.1)] and continuous flow system [OR = 2.3 (1.2–12.7)] increased risk of finding Salmonella in the individual pig.

These findings indicate that liquid-feeding and all-in all-out management of the grower–finisher barns can reduce the Salmonella prevalence.     

云南省部分猪场猪戊型肝炎的流行情况调查

为了解云南省猪群戊型肝炎感染情况,从云南省8个猪场采集166份新鲜猪粪便样品,用套式RT-PCR技术对戊型肝炎病毒(HEV)核酸进行检测,结果 21份样品阳性,阳性率为12.7%,感染率较高。通过PCR产物片段的测序分析,去除重复序列后得到11株基因序列。同源性分析结果表明,这11株毒株序列与选定的Gen Bank中基因1型、2型、3型和4型参考序列的核苷酸序列同源性分别为85.6%~87.8%,85.6%~87.8%,85.6%~95.6%和92.8%~98.9%,说明这些株毒株属于基因4型,与中国其他地区分离的毒株同源性最高,证实HEV的流行具有地理分布的特征。     

猪出血性增生性肠炎的诊断

1999年4月,某猪场发生一起育肥猪突然死亡和以肠道出血为特征的传染病.经病理剖检和病理组织学检查,诊断为猪增生性肠炎(Porcine Proliferative Enteritis),报告如下.     

猪增生性肠炎研究进展

猪增生性肠炎是由细胞内劳森菌引起的猪的接触性传染病。它主要发生在6－20周龄的生长肥育猪，临床主要表现为间歇性下痢、食欲下降和生长缓慢等。显微变化以回肠和结肠隐窝内未成熟的肠细胞发生腺瘤样增生为特征。该病目前已经在全世界流行，造成巨大的危害。由于病原认识上的混乱以及诊断上的困难等原因，该病并未引起国内兽医界的充分重视。本文综述了猪增生性肠炎研究的现状，对其病原学、流行病学、临床症状、病理变化、诊断、综合防制等进行介绍。     

Prevalence of antibodies to Lawsonia intracellularis in pig herds in Australia

Objective Proliferative enteropathy (PE) of pigs is caused by Lawsonia intracellularis. Clinical severity appears to depend, at least partly, on the infective dose and strain of L. intracellularis. Serological tests are able to detect subclinical disease. The Bioscreen ELISA for detecting L. intracellularis-specific antibodies is widely used to monitor the circulating antibody status of pigs in Australia, but its sensitivity and specificity have not been reported. The aim of the present study was to measure the seroprevalence of antibodies to L. intracellularis in growing pigs in Australia. Methods Test sera were sourced from 1817 serum samples collected from finisher pigs from 63 herds across Australia in 2001, selected from a larger sample of 180 herds to represent the contribution that each herd size makes to the number of pigs produced. The test sera were the most recent collection of pig sera from all states and samples had been stored at −80°C from 2001 until testing was conducted in 2008. Sera were tested using the BioScreen ELISA. Results All herds tested positive for L. intracellularis-specific antibodies. The mean percentage of positive samples within each herd was 84.2% (range 31.3–100%). Conclusions Lawsonia intracellularis is endemic in pig herds in Australia and cost-effective strategies to reduce reliance on antibiotics, such as vaccination and/or all-in/all-out pig flow coupled with cleaning and disinfection of pens, are warranted.     

Reproduction of proliferative enteritis in gnotobiotic pigs

Gnotobiotic pigs dosed orally with filtrates (0.8 and 0.65 micron) of intestinal mucosa from a pig affected by proliferative haemorrhagic enteropathy developed lesions of proliferative enteritis, affecting mainly the ilea. Other piglets dosed with filtrates of affected mucosa from the same source and from other proliferative haemorrhagic enteropathy or intestinal adenomatosis mucosae, did not develop lesions. All inocula contained numerous campylobacter-like organisms evident in stained smears, Campylobacter coli and C mucosalis. C coli colonised the intestines of all the pigs, C hyointestinalis (which was not detected in the inocula) did so in some affected and unaffected pigs while C mucosalis was not recovered from any of the intestines. Although other explanations are possible the number and viability of the intracellular campylobacter-like forms is likely to be the critical factor in infectivity. In affected intestines the crypts were colonised by campylobacter-like organisms, and their attachment and entry into enterocytes was associated with cellular proliferation. Immunofluorescence reactions suggested that the intracellular campylobacter-like organisms were antigenically distinct from the known Campylobacter species. It is possible, therefore, that porcine proliferative enteritis is caused by a further unidentified Campylobacter species, or that there is a marked antigenic change of C hyointestinalis or C coli on entry into porcine enterocytes.     

浅谈种猪场和规模化猪场非洲猪瘟防控

非洲猪瘟是由非洲猪瘟病毒引起的猪的一种急性、热性、高度接触性传染病。该病虽不是人畜共患病、不感染人,但对生猪产业威胁巨大,发病率高、死亡率高,疫情早期发现难、预防难、根除难,防控难度极大。种猪场和规模化猪场(以下简称“两场”)是生猪产业发展的根基和猪肉市场供给的主要来源,严防“两场”发生非洲猪瘟疫情,对保障生猪产业稳定发展和猪肉市场供给至关重要。     

Experimental reproduction of porcine proliferative enteritis

Conventional crossbred pigs from different sources and of different weights were examined for susceptibility to porcine proliferative enteritis. The ileal mucosa of pigs with the disease was emulsified and suspended in Mueller-Hinton broth. Pigs weighing 15, 120 and 200 lb (6.8, 54.5 and 91 kg) (four pigs per group) were stressed and inoculated orally with 80 ml of emulsified proliferative ilea. Severe lesions of porcine proliferative enteritis were detected in three of the four pigs weighing 6.8 kg. Mild lesions were detected in two of the four pigs in each of the other two groups. Gross lesions consisted of reticulation of the serosa, and hyperaemia and thickening of the mucosa with either fibrin or blood clots adherent to the mucosal surface. Inflammation, numerous mitotic figures and epithelial cell proliferation were observed microscopically in the crypts. Silver stained sections revealed numerous comma-shaped organisms in the crypts of infected epithelial cells. Using this method, serial reproduction of the disease was accomplished through the passage of fresh and previously frozen inocula. The virulence of the freshly prepared inoculum increased with passage through the host, whereas the inoculum prepared from tissue that had previously been frozen showed a decrease in infectivity and virulence. These data provide strong evidence for the infectious nature of this disease.     

浅谈猪增生性肠炎及其防制

猪增生性肠炎(PPE)是由细胞内劳森菌(LI)引起的一种猪常见的接触性肠道传染病。临床症状主要表现为间歇性下痢,食欲减退,生长速度减缓,饲料利用率明显下降等。对PPE的病原学、发病机理、流行病学、临床症状、诊断及综合防制等方面进行了介绍。     

Experimentally induced porcine proliferative enteritis in specific-pathogen-free pigs

Thirty-three, 10-week-old, specific-pathogen-free pigs were randomly allotted to 3 treatment groups: group 1--intragastrically given homogenized intestinal mucosa (crude inoculum) from pigs with naturally occurring proliferative enteritis; group 2--given cultures of Campylobacter sputorum subsp mucosalis; and group 3--controls. One pig from each group was killed 4, 7, 10, 14, 18, 21, 24, 28, 31, 36, and 38 days after inoculation. The earliest intestinal lesion observed in groups 1 and 2 was leukocytic exudate within crypt lumina and focal inflammation of the surrounding lamina propria. The lesions occurred primarily over ileal aggregated lymphoid nodules (Peyer's patches). These changes were followed by focal proliferation of immature crypt epithelial cells and infiltration of increasing numbers of macrophages into the lamina propria. Campylobacter sp-like organisms were observed within the cytoplasm of affected epithelial cells by light and electron microscopies. Lesions progressed to diffuse crypt cell proliferation, elongation of crypts, and loss of villi. Mucosal necrosis was not a prominent feature.     

Possible relationship of proliferative enteritis in pigs and hamsters

Three- to six-week-old hamsters were orally inoculated with broths containing one of the following cultures: Campylobacter mucosalis; C. hyointestinalis; C. coli; C. jejuni, all of porcine proliferative enteritis origin, or else C. jejuni of hamster origin. Hamsters given the last of those organisms were shown to have colonisation of their intestines by C. jejuni and 36 of 40 developed an acute enteritis. Mild hyperplasia of enterocytes in ileal crypts was evident in one hamster 2 days after it was given C. coli. No other lesions were detected. Further 3-week-old hamsters were orally inoculated with homogenised intestinal mucosa collected from 4 pigs (A-D) affected by proliferative enteritis. Lesions of proliferative enteritis were detected in 7 of 41 hamsters necropsied 10-21 days after being dosed with mucosas B or D. Marked hyperplasia of ileal enterocytes, associated with numerous intracellular Campylobacter-like organisms, were invariably detected in experimentally affected hamsters. No particular Campylobacter sp. was consistently isolated. None of the controls had demonstrable lesions. The results suggested that cross-species transmission of proliferative enteritis was possible from pigs to hamsters. Therefore a common initiating or aetiological agent may be present. No specific organism was identified as filling this role by inoculation of hamsters with pure cultures.     

对猪场沙门菌的新认识

沙门菌正成为影响欧洲猪场效益的一个日益严重的问题,这是一件令人担忧的事,因为它有传播给人类的危险。沙门菌病是一种复杂的多因素疾病,人们正在尝试各种控制方法。德国的研究表明在商品猪群净化这种疾病是可行的。     

猪场生物安全体系的建立

2007年,我省的猪存栏量大幅下降,猪肉供不应求,价格大幅上升,其中一个主要原因是猪的疾病很复杂,种猪繁殖性能低,猪的死亡率高,生产     

Prevalence and some risk factors associated with trichinellosis in backyard pig farms in Zaria, Nigeria

The aim of this study was to determine the presence of trichinellosis in backyard-farmed pigs and the risk factors associated with the infection in Zaria, Kaduna State. Serum samples were collected from 120 pigs selected at random from 50 small backyard farms, and the presence of Trichinella spp. antibodies was determined using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Data on farm management practices from the farms were obtained through the use of a structured questionnaire. The overall seroprevalence of Trichinella spp.-specific antibodies was 40 % (48/120) by ELISA. All the extensive farms sampled had at least one Trichinella-positive animal. The age and sex of the animals were not significantly (p?>?0.05) associated with the infection; however, the management systems, presence of rodents, rodent control, and access to dead pigs showed significant (p?<?0.05) association with Trichinella spp.-infected pigs on the farm. In conclusion, there was a high prevalence of antibodies to trichinellosis in backyard raised pigs in Zaria, and intensive pig farming with the adoption of proper biosecurity measures is advocated to prevent the transmission and spread of trichinellosis.     

Early lesions of proliferative enteritis in pigs and hamsters

Gnotobiotic pigs and conventional hamsters were given suspensions of intestinal mucosa from a pig with proliferative hemorrhagic enteropathy and killed 10 or 21 days later. Affected animals had evidence of marked proliferation of immature enterocytes in the intestinal crypts. Numerous Campylobacter-like organisms were in the cytoplasm of enterocytes, and in some instances, bacteria were closely associated with enterocytes. Some intracellular bacteria lying below the microvillous border were within membrane-bound structures. Immunofluorescence and electron immunogold staining with specific antibodies indicated that these organisms were antigenically different from curved bacteria in the crypt lumen of early lesions. This study indicates that the life cycle of the intracellular organisms may involve entry into crypt enterocytes from the intestinal lumen with subsequent intracellular multiplication.