Epidemiology and control of an outbreak of classical swine fever in wild boar in Switzerland

An outbreak of classical swine fever in wild boar in the southern part of Switzerland (Canton of Ticino) was investigated after the implementation of control measures in a defined infected area (the risk zone), and in a surrounding surveillance zone (the non-risk zone). After the disease had been detected, hunting was not allowed in the risk zone for over six months, during which the disease was left to run its course, but hunting was continued in the non-risk zone for one month. After seven months, a hunting strategy targeted at young animals was implemented in both zones. Between May 1998 and January 2000,1294 wild boar were shot or found dead, and diagnostic and biological data were collected and analysed. Only one animal from the non-risk zone was found to be seropositive for antibodies to the virus, whereas 179 of 528 wild boar from the risk zone were virus positive and 162 were seropositive. The proportion of virus-positive animals decreased from 62.7 per cent to zero over one year. During the first hunting season, seropositive animals were found in all age groups, but 12 months later only animals more than one year old had antibodies against the virus.     

Molecular characterization of African swine fever virus from domestic pigs in northern Tanzania during an outbreak in 2013

African swine fever (ASF) is an acute, highly contagious and deadly viral hemorrhagic fever of domestic pigs caused by African swine fever virus (ASFV), a double-stranded DNA virus of the family Asfarviridae. In this study, molecular diagnosis and characterization of outbreak ASFV in northern Tanzania, was performed on spleen, lymph node, kidney, and heart samples collected in June and July 2013 from domestic pigs that died during a hemorrhagic disease outbreak. Confirmatory diagnosis of ASF was performed using polymerase chain reaction (PCR) by partial amplification of B646L gene of ASFV encoding the major capsid protein p72 using PPA1/PPA2 primers. PCR using PPA1/PPA2 primers produced an expected PCR product size, confirming ASF outbreak in northern Tanzania. In addition, nucleotide amplification and sequencing, and phylogenetic reconstruction of the variable 3′-end of the B646L gene and complete E183L gene encoding the inner envelope transmembrane protein p54 showed that the 2013 outbreak ASFV from northern Tanzania were 100 % identical and clustered into ASFV B646L (p72) and E183L (p54) genotype X. Furthermore, the tetrameric amino acid repeats within the central variable region (CVR) of the B602L gene coding for the J9L protein had the signature BNBA(BN)₅NA with a single novel tetramer NVDI (repeat code N). The results of the present study confirm an ASF outbreak in northern Tanzania in the year 2013 and show that the present outbreak ASFV is closely related to other ASFV from ticks, warthogs, and domestic pigs previously reported from Tanzania.     

南疆仔猪首次暴发猪瘟和附红细胞体混合感染

猪瘟是危害我国养猪业的主要疫病之一 ,每年都给养猪业造成巨大的经济损失。在我国 ,由于兔化弱毒疫苗 (Ｃ株 )的普遍使用 ,单纯的典型性猪瘟已逐渐减少 ,但所谓的“非典型猪瘟”或混合感染的现象却时有发生 ,给基层兽医的诊断工作带来困难。1　发病概况2 0 0 0年 3月上旬 ,南疆地区受西伯利亚寒流的影响气温突然下降 ,喀什市某大型养猪场的仔猪突然暴发了以发热、贫血、四肢末梢和腹下皮肤发紫、ＷＢＣ和ＲＢＣ急剧下降为特征的传染病。据不完全统计 ,共发病2 6 8头 ,死亡 2 2 1头 ,发病率和死亡率分别为1 8 6 %和 82 5 %。2　临床症状患…     

Swine fever: classical swine fever and African swine fever.

Because of the clinical and pathologic similarity to common endemic diseases, introduction of CSFV or ASFV strains of moderate to low virulence represents the greatest risk to North American swine herds. Producers, veterinarians, and diagnosticians should increase their awareness of these devastating diseases and request specific diagnostic testing whenever they are suspected. Production practices that improve biosecurity will reduce the risk of introduction of CSF and ASF and limit the spread if an incursion occurs. Additional resources. The following Web sites contain excellent color photographs that will assist producers and practitioners in identifying clinical signs and gross lesions associated with CSFV and ASFV: http://www.vet.uga.edu/vpp/gray_book/FAD and http://www.pighealth.com. The latter Web site and the OIE Web site (http://www.oie.int) offer updated information on current worldwide epizootics of ASF and CSF and other swine diseases. Details of biosecurity procedures can be found at http://www.agebb.missouri.edu; see publication G2340.     

Co-circulation of two genetically distinct viruses in an outbreak of African swine fever in Mozambique: no evidence for individual co-infection

In 1998, domestic pigs originating from villages within a 40 km radius of Ulongwe in the northern Tete Province of Mozambique were held in a quarantine facility for a 3-month period prior to their importation into South Africa. Eight of a total of 25 pigs died within the first 3 weeks of quarantine of what appeared clinically and on post mortem examination to be African swine fever (ASF). Organs were collected and preserved in formol-glycerosaline and the presence of ASF virus in these specimens was confirmed by three independent polymerase chain reaction (PCR) tests. Two gene regions were characterised, namely the C-terminus end of the major immunodominant protein VP72 and the central variable region (CVR) of the 9RL open reading frame (ORF). Results confirmed the presence of two genetically distinct viruses circulating simultaneously within a single outbreak focus. However, despite the pigs being housed within the same facility, no evidence of co-infection was observed within individual animals. Comparison of the two 1998 virus variants with viruses causing historical outbreaks of the disease in Mozambique revealed that these viruses belong to two distinct genotypes which are unrelated to viruses causing outbreaks between 1960 and 1994. In addition, the CVR and p72 gene regions of one of the 1998 Mozambique virus variants (variant-40) was shown to be identical to the virus recovered from an ASF outbreak in Madagascar in the same year, whilst the other (variant-92) was identical to a 1988 pig isolate from Zambia.     

Descriptive epidemiology of a classical swine fever outbreak in the Limburg Province of Belgium in 1997

This paper describes the epidemiological characteristics of the 1997 Classical Swine Fever (CSF) outbreak that occurred in the Limburg Province of Belgium, where there is a policy of non-vaccination, intensive surveillance and eradication. Between 30 June and 17 July 1997, eight herds, located in three different areas, were confirmed to be CSF-positive. CSF virus was transmitted from the primary infected herd of one area to another five herds in the same area and to one herd in a different area. The mode of virus introduction for this primary infected herd and for the one herd that was not infected by this primary herd could not be determined. Clinical, serological, and virological findings indicated that the CSF-infected herds were detected in an early stage of the infection. The early detection of the infection together with a preventive stamping out procedure resulted in a rapid elimination of the CSF virus. A total of 46,561 pigs were slaughtered to control the spread of the infection. Another 27,579 pigs were slaughtered in the framework of the market support. The total direct costs of the episode were estimated at [symbol: see text] 10,893,337.     

美国—自繁自养猪场爆发猪恶性卡他热

恶性卡他热是一种通常可感染包括猪在内的多种动物的散发性、致死性病毒病。能导致绵羊恶性卡他热的绵羊疱疹病毒2型(Ovine herpesvirus type 2,OvHV-2),可引起猪产生非特异性的临床症状,偶尔可引起猪死亡。美国一自繁自养猪场爆发的恶性卡他热,是通过从两头早先接触过绵羊、临床上受到感染的成年猪体内检测出OvHV-2的DNA后得到确诊的。在41头表现嗜睡、厌食和发热等临床症状的猪中,22头康复,19头死亡。两头临床受到感染的怀孕母猪出现了流产。通过PCR方法对病猪脾、脑和肺组织检测后鉴定出OvHV-2DNA。BLAST分析表明,PCR扩增产物测序结果与OvHV-2衣壳蛋白保守区的一致。由于猪恶性卡他热没有特异性的临床症状,而且呈少发、散发,因此很难诊断。PCR方法和血清学试验可用于本病的确诊。兽医应该可以从非特异性的临床症状、间歇性死亡和与羊的接触史等方面对猪恶性卡他热进行鉴别诊断。     

经典型猪瘟(CSF)

该病在一些欧洲国家、南美以及远东呈显现地方流行，在德国、意大利的撒丁岛等欧洲国家，野猪常常带毒呈地方流行。2000年在保加利亚和泰国爆发了猪CSF。1999年阿根廷、哥伦比亚、德国、意大利、卢森堡爆发了该病。撒丁岛在1998年至1999年6月爆发了17起经典型猪瘟。非洲猪瘟在撒丁岛也呈地方性流行。1999年3     

Descriptive epidemiology of the outbreak of classical swine fever in Catalonia (Spain), 2001/02

Spain suffered an outbreak of classical swine fever between June 14, 2001 and May 7, 2002, which affected 49 herds; this paper describes the epidemiological characteristics of the 39 herds that were affected in Catalonia, an area of high pig density in the north east of Spain. The outbreak took place in two waves, which affected first the province of Lleida and then Barcelona. A total of 291,058 animals were slaughtered, 59,595 belonging to infected herds; 22 of the infected herds were detected on the basis of clinical suspicion on the part of the farmer or farm veterinarian, and the other 17 were detected by surveillance methods. The transmission of the virus between herds was attributed to the movement of people in 23 per cent of the cases, to animals in 13 per cent, vehicles in 10 per cent, proximity 18 per cent, the pick-up service of the rendering plant in 8 per cent and slurry in 5 per cent; in the other nine herds (23 per cent) the route of entry of the disease could not be established. The viruses isolated in the two waves of the outbreak were 100 per cent homologous and belonged to subgroup 2.3. The origin of the outbreak remains unknown.