Intestinal chlamydial infection concurrent with postweaning multisystemic wasting syndrome in pigs
Intestinal chlamydial infection concurrent with postweaning multisystemic wasting syndrome in pigs
复制标题
DOI：
10.1136/vr.146.1.21
复制
发表时间：
2000-01-01
影响因子：
2.2
通讯作者：
Sierra, MA
中科院分区：
文献类型：
--
作者：
Carrasco, L;Segalés, J;Sierra, MA
断奶后多系统衰竭综合征(PMWS)是最近出现的一种由猪环状病毒(PCV)2型引起的猪疾病，影响育肥猪的后期，临床特征是身体状况不佳和淋巴结肿大。镜下主要表现为淋巴器官淋巴细胞耗竭、组织细胞渗入和合体细胞形成(Segales等1997，Ellis等1998,1999，Kiupel等1998，Morosov等1998，Rodriguez-Arrioja等1999，Rosell等1999)。有证据表明，受PMWS影响的猪可能会受到免疫抑制，导致其他并发感染的发生率增加，或者改变某些疾病的临床表现。与PMWS有关的寄生虫、细菌或病毒感染已被报道；在受PMWS影响的猪中发现卡氏肺孢子虫(Clark 1997)，最近的报告描述了PMWS感染的猪同时感染Aujeszky病病毒(Rodriguez-Arrioja等人1999)和/或猪呼吸和生殖综合征病毒(Morosv等人1998，Rodriguez-Arrioja等1999，Rosell等1999)。在临床未见明显病变的仔猪(Zahn等1995)和育肥猪(Szeredi等1996)的样品中存在衣原体抗体和抗原，这表明衣原体不是猪的主要肠道病原体。然而，Pospischil和Wood(1987)报告了衣原体在涉及其他细菌的混合感染中作为猪消化道病原体的潜在作用。这一简短的交流描述了一例12周龄猪的PCV和肠道衣原体感染的并发病例。在西班牙南部一个有100头母猪的连续流水式养殖场，7%的早期育肥猪表现出身体状况不佳、轻度高热(40摄氏度)和皮肤苍白。在一些受影响的动物身上也发现了轻微的腹泻和偶尔的流血事件。在对一头12周大的有代表性的安乐死猪进行尸检后，兽医报告了明显的淋巴结肿大，主要是肠系膜淋巴结，以及空肠和回肠壁的广泛增厚。医生怀疑为增殖性回肠炎(猪肠腺瘤病)，并提交肠系膜淋巴结、空肠、回肠和结肠组织标本进行组织学检查。组织样本浸泡在10%中性缓冲福尔马林中固定，并在石蜡中常规处理以进行光学显微镜检查。3~4 PM厚度的组织切片，苏木精-伊红染色。以Rosell等人(1999)描述的方法为基础的原位杂交技术被用于检测PCV核酸。为了进行超微结构的研究，将福尔马林固定的样品切成1 mm的立方体，在含有蔗糖的01M磷酸盐缓冲液中清洗过夜，后固定在1%四氧化二臭氧中，脱毛。
POSTWEANING multisystemic wasting syndrome (PMws), a recently emerged porcine disease attributed to porcine cir-covirus (Pcv) type 2, affects late nursery and fattening pigs and is clinically characterised by poor body condition and lymph node enlargement. The main microscopic lesions con-sist of lymphocyte depletion together with histiocytic infil-trates and syncytial cell formation in lymphoid organs (Segales and others 1997, Ellis and others 1998, 1999, Kiupel and others 1998, Morozov and others 1998, Rodriguez-Arrioja and others 1999, Rosell and others 1999). There is some evidence to suggest that PMws-affected pigs may be immunosuppressed, resulting in an increase in the incidence of other concurrent infections, or a modification of the clinical presentation of some diseases. Concurrent parasitic, bacterial or viral infections associated with PMWS have been reported; Pneumocystis carinii has been found in the lungs of PMws-affected pigs (Clark 1997) and recent reports have described PMws-affected pigs simultaneously infected with Aujeszky's disease virus (Rodriguez-Arrioja and others 1999) and/or porcine respiratory and reproductive syndrome virus (Morozov and others 1998, Rodriguez-Arrioja and others 1999, Rosell and others 1999). The existence of chlamydial antibodies and antigens in samples from piglets (Zahn and others 1995) and finishing pigs (Szeredi and others 1996) with no significant clinical lesions, has suggested that Chlamydia species is not a primary intestinal pathogen in pigs. However, the potential role for Chlamydia species as a porcinealimentary tract pathogen in mixed infections involving other bacteria has been reported by Pospischil and Wood (1987). This short communication describes a case of concurrent PCV and intestinal chlamydial infection in a 12-week-old pig. Seven per cent ofearly fattening pigs from a single site, continuous flow farm containing 100 sows (farrow-to-finish) in southern Spain, showed poor body condition, mild hyperthermia (40 C) and paleness of the skin. Mild diarrhoea with occasional bloodyscours was also seen in some of the affected animals. Following necropsy ofa euthanased, representative, 12-week-old pig, the veterinary practitioner reported a marked enlargement of the lymph nodes, mainly the mesenteric lymph nodes, and an extensive thickening of the jejunal and ileal wall. Proliferative ileitis (porcine intestinal adenomatosis) was suspected by the practitioner, and tissue specimens of the mesenteric lymph nodes, jejunum, ileum and colon were submitted for histological examination. Tissue samples were fixed by immersion in 10 per cent neutral buffered formalin and routinely processed in paraffin for light microscopy. Tissue sections of 3 to 4 pm thickness were stained with haematoxylin and eosin. An in situ hybridisation technique, based on the method describedby Rosell and oth-ers (1999), was used to detect PCV nucleic acid. For ultra-structural study, formalin-fixed samples were cut into 1 mm cubes, washed overnight in 0 1M phosphate buffer contain-ing sucrose, postfixed in 1 per cent osmium tetroxide, dehy-