译者的话：<<

非洲猪瘟病毒会通过猪的所有体液散毒，其中，血液中病毒浓度最高。猪可通过鼻对鼻接触、精液、母乳、粪/口、含有病毒颗粒的皮下注射以及摄入受感染猪的组织而感染。该病毒的潜伏期为3-14天，临床症状包括无精打采、皮肤红斑、猪扎堆、发热、血痢疾和猝死。

关于ASFV疫苗将在中国上市（或已经上市）的报道广为流传。兽医和生产者传统上用来控制任何病原体的第一个工具就是疫苗，疫苗能够成功地减少受感染猪群的死亡率并阻止病原体在阴性动物之间的传播。一种好的疫苗的另一个特征是能够鉴别免疫过疫苗的猪和感染过野毒的猪。

科学无国界，疫病无国界。在全球范围内，为防止ASFV的传播和循环提供技术帮助和知识是每一个具有养猪业最专业知识的个人的责任。

ASF的全球分布 

ASFV in the world swine herd<<

在官方报道全球第一养猪大国出现ASFV之前，ASFV已经在过去的近100年里广泛传播，从非洲到伊比利亚半岛，到东欧，俄罗斯，最后进入亚洲。病毒的转移通常被认为是病原体随人移动的结果；据推测，病毒的转移是由受感染的猪或猪肉随生产者或工作人员的活动而转移的。

Prior to official reports of ASFV in the largest swine herd in the world, ASFV was commonly known to have spread widely over the past nearly 100 years from Africa to the Iberian Peninsula, to eastern Europe, across Russia, and finally into Asia. Movement of the virus is commonly understood to be the result of “people or human” movement of the pathogen; the virus movement speculated to be by movement of either infected pigs or meat by producers or staff.

ASFV是已知和已报道的能感染所有年龄段猪的最致命病毒之一（若按死亡率衡量不是最致命的话）。在亚洲的小型猪场中，该病毒可能导致猪群中100%的猪死亡（请注意，幸存的猪通常在死亡前被出售，导致报告数量低于真实死亡数量）。在更大规模的猪场中，已发现一小部分猪能在ASFV爆发中幸存下来。ASFV感染的临床表现已被广泛刊发，这些表现通常被认为包括出血热、在猪群中缓慢传播和高死亡率。这些已发表的报告在亚洲大型田间条件下有不同之处，这将在本届会议期间加以审查。

ASFV is known and reported to be one of the deadliest viruses (if not the deadliest as measured by mortality) to infect swine of all ages. In small stakeholder operations in Asia, the virus may result in death loss of 100% of the pigs in the herd (note that any surviving pigs are commonly sold prior to death resulting in under reporting of true mortality). In larger operations, a small percentage of pigs have been observed and reported to survive an ASFV episode. Clinical presentation of ASFV infection is widely published and commonly understood to include a hemorrhagic fever, slow spread in a population, and high mortality. There are variations from these published reports under large field condi­tions in Asia and will be reviewed during this session.

从2018年8月到2019年8月，中国33个省中有32个省官方报道了160例非洲猪瘟病例。该病毒已在中国各地蔓延（现已波及10个亚洲国家），感染了所有年龄段和品系的猪。此外，所有类型的生产体系都受到了感染，并在田间条件下进行了观察，包括所有不同设计和运营模式的小型传统猪场（500头以下）到现代化的西式猪场（8000头以上母猪）。

In China, from August 2018 until August 2019, there were offi­cial reports of 160 cases in 32 of the 33 provinces in China. The virus has spread throughout China (and now in 10 countries in Asia), affecting pigs of all ages and genetics. Additionally, all types of production systems have been infected and observed un­der field conditions including smaller traditional farms (less than 500 head) to modern western style barns (over 8,000 sows) of all designs and operational practices.

目前，据非官方报道，中国的生猪数量大幅减少，人们普遍担心，从2018年8月开始的官方报告中记录的总损失数量被低估了。虽然官方报告确实报告了中国猪群数量的减少，但人们普遍猜测，官方报告低估了由于猪群数量减少而造成的全方位损失。目前还没有准确的或普遍接受的方法来确定确切的损失量，许多报告的作者推测，至少损失了30%的猪群，而还有许多来源的报告所认为的损失程度不一，但母猪群损失接近50%以上。且不管具体的损失究竟有多少，田间的观察证实这种病毒的影响与报告所述的一样严重。

Currently, the pig population in China has been unofficially re­ported to be dramatically reduced with common concern that total losses documented by official reporting starting in August 2018 is understated. While official reports do report a decline in the size of the China herd, it is widely speculated that official reports are under-estimating the full extent of total loss due to ASFV. There is no accurate or commonly accepted method to determine the exact amount of loss, with various authors speculating a minimum of 30% reduction in herd size to many sources reporting losses at vari­ous levels approaching higher than 50% loss of the China sow herd. Regardless of the exact loss, field observations confirm the severe impact of this virus is as widely published.

关于ASFV疫苗将在中国上市（或已经上市）的报道广为流传。兽医和生产者传统上用来控制任何病原体的第一个工具就是疫苗，疫苗能够成功地减少受感染猪群的死亡率并阻止病原体在阴性动物之间的传播。一种好的疫苗的另一个特征是能够鉴别免疫过疫苗的猪和感染过野毒的猪之间的区别。几十年来，研究人员一直在努力开发一种有效的ASFV疫苗，在撰写本文时，尚未有官方批准的ASFV疫苗来预防阴性猪感染²。

Reports that vaccines for ASFV will be (or already are) available in China are widely described. The first tool that veterinarians and producers traditionally implement to control any pathogen is a vaccine which successfully results in both reduction of mortali­ty in an affected population and stops the spread of the pathogen between naïve animals. One additional feature of a good vaccine is the ability to discern the difference between the vaccinated pig and a pig exposed and infected with field virus. Researchers have struggled for decades to develop an effective ASFV vaccine and as of this writing, there is no officially approved vaccine for ASFV to prevent infection of naïve pigs.²

ASFV的流行病学 

ASFV epidemiology<<

ASFV的流行病学信息在受控的研究条件下被广泛发表：该病毒会通过猪的所有体液散毒，其中，血液中病毒浓度最高。猪可通过鼻对鼻接触、精液、母乳、粪/口、含有病毒颗粒的皮下注射以及摄入受感染猪的组织而感染。该病毒的潜伏期为3-14天，临床症状包括无精打采、皮肤红斑、猪扎堆、发热、血痢疾和猝死。

More epidemiological research and publication is needed as field reports from China in large commercial operations with potential co-infections dispute some of these reported results. Some of the variation in field reports may be explained by dif­ferences in virus isolate commonly reported as High, Moderate and Low virulence. These ASFV isolates also may have different field presentations and pathogenesis described as Peracute, Acute, Subacute and Chronic. Field observations support these reported differences in clinical presentation.

ASFV的鉴别诊断包括但不限于经典猪瘟、蓝耳（猪繁殖和呼吸综合征）、伪狂犬、沙门氏菌和断奶后多系统衰竭综合征以及包括梭状芽胞杆菌和链球菌在内的其他致病菌。

Differential diagnosis for ASFV include, but are not limited to, classical swine fever, porcine reproductive and respiratory syndrome, pseudorabies virus, salmonella, and post-weaning mul­tisystem wasting syndrome and other bacterial pathogens includ­ing Clostridium and Streptococcus.

ASFV具有高致病性，但未见高传播性的报道。一些作者将此描述为“接触传染力”（与其他病原体如口蹄疫病毒相比，ASFV具有高死亡率和低感染率）³。在病毒未得到控制和对流行病学数据进行了监测的大规模商品场中的临床田间病例中，总死亡率可在数天内增加一倍以上，直至造成大多数猪只死亡。

ASFV is highly pathogenic, but not reported to be highly trans­missible. Some authors describe this as “contagiosity” (there may be high mortality with low infection rate when compared to other pathogens like FMDV).³ In clinical field cases in large populations of commercial pigs where the virus has been left un­controlled and epidemiological data has been monitored, total mortality can more than double in the matter of days until the majority of the population is deceased.

已有研究已对亚洲猪群的感染源进行了调查，以了解疾病的进入途径，以便今后预防病毒向区域内的其他猪场传播。总的来说，亚洲的田间观察支持了病毒在该地区的快速传播，推测病毒的传播途径包括受感染的猪、受感染的肉、受污染的病媒、鼠类、苍蝇、蚊子、工作人员、饲料的移动，以及缺乏执行适当的生物安全规程。受污染的饲料在疾病传播动力学中所扮演的角色不容忽视。在ASF病毒的各种传播途径中，死猪尸体处理不当和感染猪只的转移是最常见的把ASFV在全国各地传播的方法。死于ASFV的猪需要正确的处理并加强生物安全措施，以限制ASFV向未感染猪群的传播，因为死猪尸体散播的病毒量是很大的。

Investigations into the source of the infections into a population in Asia have been conducted to understand the routes of entry which may allow for future prevention of movement of the virus to other area farms. In general, field observations in Asia support rapid area spread with speculated routes of movement of the virus attributed to movement of infected pigs, movement of infected meat, contaminated fomites, rats, flies, mosquitoes, staff, feed, and lack of implementation of proper biosecurity protocols. The role of contaminated feed cannot be overlooked in the transmis­sion dynamics. Improper disposal of the carcasses and movement of infected pigs are high on the list of methods that may have moved this virus across all of China. Pigs that have died from ASFV require proper disposal and enhanced biosecurity practices to limit the spread of ASFV to naïve populations since carcasses are shedding high levels of virus.

猪场清群和净化程序已经实施并在田间条件下进行了观察，结果差异很大。一个猪场在清群之后，一定要实施彻底的清洁和消毒程序以去除所有有机物质和病毒颗粒，这一点是至关重要的，因为这可以防止病毒向下一批猪传播，从而使猪场保持健康，免受ASFV感染。目前普遍接受的针对其他病毒（包括但不限于PEDV或PRRS）的操作规程已在田间得到成功应用。中国正在尝试使用检测和淘汰技术从母猪群中净化ASF病毒⁴。这种采用闭群、部分清群和全群采样的净化方法或许行得通，还需要进一步的研究和文献来证明针对非洲猪瘟这种病原体是否有效。

Site depopulation and cleanup protocols have been implemented and observed under field conditions and vary widely. It is critical that following depopulation of a site, a cleaning and disinfection protocol that removes all organic material and viral particles is completed to prevent viral transmission to the next group of pigs and for the site to remain healthy and free from ASFV. Commonly accepted protocols for other viruses (including but not limited to PEDV or PRRS) have been successfully used in the field. Attempts to eliminate ASF virus from sow populations using test and re­moval techniques are being reported in China.⁴ This elimination technique using herd closure, partial depopulation and whole herd sampling methods may hold promise and needs further research and documentation to understand if effective for this pathogen.

为了确保ASFV不进入其他场点，应进行全面的生物安全评估，以确保有关人员入场、卡车运输、装载、饲料、隔离期以及其他可能的入场途径的规程都正确的成文，对工作人员进行相关主题的培训和教育，并正确地执行标准操作流程。还有至关重要的一步是，确保每天的监督也能到位，以便对猪场员工在培训教育和操作方面的任何不足之处进行日常审查和纠正。

To ensure that ASFV does not enter other sites, a full biosecurity evaluation should be conducted to ensure that protocols regard­ing personnel entry, trucking, loading, feed, downtime, and other possible routes of entry are properly written, staff are educated on the topics, and standard operating procedures are properly imple­mented. A critical step is to be sure daily monitoring is also com­pleted to maintain daily review and correction of any deficiencies in implementation and education by staff on the farm.

为了防止更多的场点和猪场受到感染和损失，常常需要额外的资本支出来改善生物安全。西班牙是唯一一个在1995年成功净化了ASFV的国家，在此之前，西班牙多年来一直试图将ASFV从其猪群中净化，但均以失败告终²。亚洲现在面临着一个重要的决策：ASFV不仅在中国各处传播，而且也已进入其他国家，如果不谨慎地实施干预措施，阻止病毒在猪场之间和其他国家之间的传播，那么病毒可能会继续传播。在全球范围内，为防止ASFV的传播和循环提供技术帮助和知识是每一个具有养猪业最专业知识的个人的责任。在美国，由养猪业的领军者打头阵将ASFV拒之国门外，政府也将紧随其后。

Additional capital expenditure projects to improve biosecurity are often necessary to prevent the infection and loss of more sites and farms. The only country that has successfully eliminated ASFV is Spain, in 1995, after years of unsuccessful attempts to eliminate ASFV from their national herd.²Asia now faces this decision as the virus has not only spread through China, but also into adjourning countries and may continue to spread without careful implementation of interventions to stop viral spread be­tween farms and additional countries. All across the world it is the responsibility of the individuals with the greatest expertise in the swine industry to provide assistance and knowledge on pre­venting the spread and circulation of ASFV. In the United States, with leaders in the swine industry leading the charge to keep ASFV out of the country, the government will follow.

参考文献 References<<

^1. 2019. ASF Situation in Asia Update. FAO ASF Situation Update - African Swine Fever (ASF) - FAO Emergency Prevention System for Animal Health (EMPRES-AH). Food and Agriculture Organization of the United Nations.

^2. Sanchez-Vizcaino, Jose M., et al. 2019. African swine fever virus. Diseases of Swine. 11:443-452.

^3. Depner, K. 5 Aug. 2018. The World of ASF A World Apart. 7th ECPHM Resi­dent Workshop.

^4. Yan Jason 2019. Why New Generation Testing and Removal is Winning ASF Control in China. Proceedings, 2019 Leman China University of Minnesota. Zhengzhou, China. October, 2019.