PCR results are diagnostic test results, not a diagnosis. The diagnostician is an investigator and should employ all of the tools at his command. An expert with experience in China reviews how ASF should be diagnosed.
PCR结果只是诊断试验结果，而不是诊断。诊断师是一名调查员，应该根据他的命令使用所有的工具。一位在中国有经验的专家回顾了如何诊断ASF。
African swine fever is a severe viral disease of pigs of all ages. In recent years it has devastated the swine industry in many different countries. ASF actually spreads rather slowly and it is possible to curtail its geographic spread by appropriate action. Early definitive diagnosis is a key element to avoid spread. An initial field diagnosis of African swine fever can be made from clinical signs and necropsy findings.
非洲猪瘟是各种年龄猪的一种严重的病毒性疾病。近年来，它在许多不同的国家摧毁了养猪业。ASF的传播速度实际上相当缓慢，可以通过适当的行动来限制其水平传播。早期明确诊断是避免传播的关键因素。非洲猪瘟的初步现场诊断可根据临床症状和尸检结果作出。
Clinical signs:
In the initial phase of the disease, animals are often found peracutely dead with cyanosis of the legs, ears, and the extremities. Often there is high fever 40 - 42° C, vomiting, diarrhea that may be bloody or black (Photo 1, right), depression, abortions (Photo 1, left), bloody nasal discharge (epistaxis), and increasing death losses.
临床症状：
在疾病的最初阶段，动物经常被发现死于腿部、耳朵和四肢的发绀。经常有高烧40-42°C，呕吐，腹泻，可能是血或黑(图1，右)，抑郁，流产(图1，左)，血鼻分泌物(鼻出血)，并增加死亡损失。
Photo 1. Abortion storm (left) and bloody diarrhea in sows (right).
P 流产风暴(左)和母猪流血腹泻(右)。
The low virulence (vaccine) strains cause a mild chronic atypical form of the disease with few deaths. Females generally exhibit chronic respiratory disease and chronic infertility. The longer time course to obvious illness or lack of observed clinical signs among the chronic vaccine virus pigs is often interpreted by the farm as a long incubation period.
低毒力(疫苗)株导致一种轻微的慢性非典型疾病，几乎没有死亡。母猪一般表现为慢性呼吸道疾病和慢性不孕症。慢性疫苗病毒猪出现明显疾病或缺乏观察到的临床症状的时间较长，通常被农场解释为一个较长的潜伏期。
Lesions at necropsy
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Epiglottis and trachea may be reddened, and there is generally an interstitial pneumonia with inter-lobular edema. Sometimes there is a fibrinonecrotic pleuropneumonia that resembles APP.
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A fibrinous myocarditis and pericarditis may be present, and the thorax and abdomen may have an excessive amount of bloody or serosanguinous fluid.
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The mesenteric lymph nodes and particularly the gastro-hepatic nodes may be enlarged, edematous, and appear to be necro-hemorrhagic on the cut surface (Photo 2).
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The spleen may be enlarged with multiple infarcts present or it may be essentially normal.
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The liver often contains frank hemorrhages.
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The kidneys may have numerous infarcts, and petechial and ecchymotic hemorrhages (Photo 3). There may be a striking peri-renal edema. The fundic stomach is often severely reddened and eroded, and the spiral colon may be filled with a bloody content. It is not unusual to find paintbrush hemorrhages on the abdominal viscera.
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A fibrinous meningitis may be evident in the brain.
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尸检病灶
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会厌炎和气管可能发红，一般有间质性肺炎伴小叶间水肿。有时会出现类似APP的纤维蛋白变性胸膜肺炎。
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可出现纤维性心肌炎和心包炎，胸部和腹部可能有过多的血或浆液。
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肠系膜淋巴结，尤其是胃-肝淋巴结可能增大，水肿，并出现坏死出血性在切割表面(照片2)。
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脾脏可能扩大，多个梗死灶出现，或它可能基本上是正常的。
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肝脏经常有大量出血。
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肾脏可能有许多梗塞，点状出血和异位出血(图3)。可能有明显的肾周水肿。胃底部经常严重发红和糜烂，螺旋结肠可能充满血淋淋的内容物。在腹部内脏上发现油漆刷出血并不少见。
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纤维蛋白性脑膜炎在大脑中可能很明显。
Photo 2. Hemorrhage and necrosis in gastrohepatic lymph node.
图2.胃肝淋巴结出血坏死。
Photo 3. Edema and petechial hemorrhages in kidney.
图3.肾脏水肿和点状出血。
The severity of the lesions among pigs is variable and it is generally suggested that multiple pigs be opened.
Necropsy should be done with a professional concern for biosafety, but necropsy does not introduce unique disease hazards to an infected farm and does provide valuable information not attainable by less aggressive diagnostic approaches.
猪的皮肤损伤的严重程度是不同的，而且 一般建议打开多头猪。
尸检应该在专业上关注生物安全，但尸检不会给受感染的农场带来独特的疾病危害，而且确实提供了不那么积极的诊断方法无法获得的宝贵信息。
Laboratory techniques
PCR: The diagnosis of ASF is usually verified by a positive nucleic acid test and by the ruling out of other common causes of similar lesions. The most common is PCR for the P72 gene. Lung (preferred sample in our lab), kidney, spleen, lymph node, serum, and blood are all excellent test samples for PCR. Oral swabs and oral fluids are extremely popular but the amount of virus is several logs less than what is generally found in blood and tissue, so false-negative results are rather common. Fluorescent qPCR and conventional PCR are employed for testing. Conventional PCR offers a convenient route to gene sequencing.
实验室技术
PCR： ASF的诊断通常由阳性核酸试验和排除其他常见的类似病变的原因来证实。最常见的是P72基因的PCR。肺(实验室首选样本)、肾、脾、淋巴结、血清和血液都是PCR的最佳检测样本。口腔拭子和唾液非常流行，但是病毒的数量比在血液和组织中通常发现的要少一些，所以假阴性结果是相当常见的。荧光定量PCR和常规PCR检测。传统的PCR技术为基因测序提供了一条方便的途径。
Where the gene deleted vaccine has been used deliberately or the gene deleted virus strain variant has been introduced accidentally, nucleic acid testing may fail in some animals because the amount of virus that is produced is much lower compared to the wild-type field virus. However, where good samples are available from tissue or blood, a nucleic acid test for the deleted genes of the vaccine virus can be done. After a positive test for the P72 gene, a PCR test for the gene deleted vaccine looking for the presence of DNA from MGF 360 – 505 R and CD2v can be done to determine if the problem virus is the field virus or the gene deleted vaccine virus.
如果基因缺失疫苗是人为故意使用的，或者基因缺失病毒变异株是偶然引入的，那么核酸检测在某些动物身上可能会失败，因为与野生病毒相比，产生的病毒数量要低得多。然而，如果可以从组织或血液中获得良好的样本，就可以对疫苗病毒的缺失基因进行核酸测试。在对P72基因进行阳性检测后，对基因缺失疫苗进行PCR检测，寻找MGF 360~505 R和CD2v中是否存在DNA，以确定问题病毒是野毒还是基因缺失疫苗病毒。
Loop-mediated isothermal amplification (LAMP) offers a rapid, cheap, flexible, and extremely sensitive nucleic acid alternative that requires little specialized equipment, and seems well-favoured for mass testing such as monitoring/screening at slaughter.
环介导等温放大(LAMP) 它提供了一种快速、廉价、灵活和极其敏感的核酸替代品，几乎不需要专门的设备，而且似乎很适合大规模检测，如屠宰时的监测/筛选。
Serology may be used to determine if the animals have been exposed to the ASF virus when the time course from infection to testing has been long enough that the period of viremia and presence of virus in the tissues has passed or if good samples from necropsy are not available.
血清学 可用于确定动物是否接触过ASF病毒，而从感染到检测的时间已经足够长，以致病毒血症和病毒在组织中的存在时间已过，或无法从尸检中获得良好的样本。
There are a number of ELISA kits available to look for the presence of antibody to P 72, P 30, and other ASF antigens. Such test kits are often used to identify and typically cull groups of females that have been vaccinated deliberately or accidentally exposed to the illegal vaccine virus.
有一些 ELISA法 试剂盒可用于寻找抗P72，P30和其他ASF抗原的抗体。这类试剂盒通常被用来识别和典型地挑选被故意接种或意外接触非法疫苗病毒的母猪。
There is an antigen capture ELISA card test, but it is severely lacking in sensitivity, and its use is generally limited to those cases where a quick false negative result is desired.
On histopathologic examination there is a generalized vasculitis with infarction, hemorrhage, and thrombosis in multiple organs, particularly the lung, spleen, lymph nodes, kidneys, brain, and gut. There is massive lymphoid destruction in the lymph nodes and spleen, and vacuolation of alveolar macrophages. Necrosis and ulceration of the colonic epithelium is common (Photo 4).
T检测卡 是一个抗原捕获ELISA卡试验，但它是严重缺乏敏感性，它的使用一般限于那些情况下，快速假阴性的结果是想要的。
在……上面 组织病理学检查 在多个器官，特别是肺、脾、淋巴结、肾脏、脑和肠道中，有一种伴有梗死、出血和血栓形成的广泛性血管炎。淋巴结和脾脏有大量淋巴样破坏，肺泡巨噬细胞空泡化。结肠上皮坏死和溃疡是常见的(图4)。
Photo 4. Vascular thrombosis, infarction, ulceration in colonic mucosa.
图4.血管血栓形成、梗死、结肠粘膜溃疡。
The use of histopathology to verify the typical chronic lesions of the gene-deleted vaccine can be very useful. Pigs that have received those vaccines for ASF will usually have chronic-active healing and fibrosing vascular lesions including thrombi and infarcts in the gut, liver, lymphoid tissues, heart, and kidneys. The lymph nodes may have areas of hemorrhage, necrosis and lymphoid destruction and fibrosing and healing zones. Vaccinated breeding animals may have massive zones of lung necrosis and fibrosis that are often mistaken for chronic APP. The vaccine virus might not kill the pig but the pig is often unable to clear itself of the vaccine virus.
使用 组织病理学检查基因缺失疫苗的典型慢性病变 非常有用。接种了ASF疫苗的猪通常会有慢性活跃的愈合和纤维化血管病变，包括肠、肝、淋巴组织、心脏和肾脏中的血栓和梗死。淋巴结可能有出血，坏死和淋巴样破坏，纤维化和愈合区。接种疫苗的繁殖动物可能有大量的肺坏死和纤维化区域，这些区域往往被误认为慢性APP。疫苗病毒可能不会死猪，但猪通常无法清除疫苗病毒。
One should remember that PCR is a great tool but not infallible, and, relative to the actual farm situation, is not 100% accurate. This not to say that PCR is unreliable. Au contraire... but still, PCR results are diagnostic test results not a diagnosis. Thediagnostician is an investigator and should employ all of the tools at his command. When ASF is suspected, some care in biosafety is indicated as always, and even more so. But there are several ASF look-alike diseases and generally speaking a diagnosis of the actual cause of the problem is required in addition to a negative test for ASF, which may require more observational intervention than popping out an inguinal node or exteriorizing the spleen through a keyhole incision.
人们应当记住，PCR是一个很好的工具，但不是绝对正确的，而且相对于实际的农场情况，并不是100%的准确。这并不是说PCR是不可靠的。反差..。不过， P CR结果是诊断测试结果，而不是诊断。 这个 诊断师是一名调查员，应该在他的指挥下使用所有的工具。当怀疑ASF时，生物安全方面的一些关注将一如既往，甚至更多。但是有几种ASF看起来相似的疾病，一般来说，除了对ASF的阴性测试外，还需要诊断出问题的实际原因，这可能需要更多的观察干预，而不是通过锁孔切口突出腹股沟结节或脾脏。
