Swine Disease Global Surveillance Report, Mar. 2020(Part 1)
European Food Safety Authority (EFSA) report: The European Commission requested EFSA provide an updated analysis of the epidemiology of ASF. Key findings and identified gaps to inform sustainable control strategies are summarized. A few to note:
ASF has been progressively, but slowly, expanding mainly in a southwesterly direction.
There is evidence in all affected countries that is suggestive of human-mediated translocation of the virus. The most obvious examples of this include the introduction of ASFV into Belgium, Czech Republi and western Poland.
Currently, there is no evidence that large fences have been effective for the containment of wild suids. Some new large-scale fences are under construction, and their effectiveness in separating wild boar populations will need to be evaluated in the future.
Greece confirms the first case of African swine fever (ASF): The disease was found in a backyard farm less than 50 miles from the border with Bulgaria.
New ASF outbreak in Myanmar: After almost five months since its first case Maynmar reported new outbreaks in the north of the country.
4. ASF在菲律宾的蔓延：菲律宾政府下令扑杀了Davao Occidental省仅剩的10万头生猪。
Expansion in the Philippines: Government ordered the culling of what remained of the 100,000 hogs in Davao occidental province.
Foot-and-mouth disease (FMD) outbreak in Kenya: An outbreak of FMD was confirmed in the northern part of the country.
ASF in Europe 2018-2019: Lessons Learned
The European Food Safety Authority (EFSA) released epidemiological analyses of ASF in the European Union (Nov 2018-Dec 2019).
ASF has been progressively, but slowly, expanding mainly in a southwesterly direction.
All ASF-affected areas are essentially contiguous, except for isolated introductions in Czech Republic (now resolved), western Poland and Belgium.
In countries where the disease has been present in wild boar for more than t wo years (Baltic countries, Poland and Romania), results confirm the presence of seasonality in ASF detections. The number of notifications of ASF in wild boar were highest in winter and summer and lowest in spring. In domestic pigs, only a summer peak was evident based on notified outbreaks in these countries.
An analysis was performed to assess the speed of natural propagation of ASF in wild boar populations. The median velocity of infection in Belgium, Czech Republic, Estonia, Hungary, Latvia, Lithuania, and Poland was between 2.9 and 11.7 km/year.
There is evidence in all affected countries thatis suggestive of human-mediated translocation of the virus. The most obviousexamples of this include the introduction of ASFV into Belgium, Czech Republic andwestern Poland. Moreover, the analysis of less obvious occurrences revealed thathuman-mediated translocation of ASFV remains a very important factor in contributingto the translocations of ASFV both within and between wild boar populations, ofparticular impact in the south-eastern affected region.
6. 识别家猪/野猪群体之间的关键风险因素是加强生物安全和其他风险缓解措施的一个关键目标。在这方面，我们结合2014 - 2019年爱沙尼亚野猪ASF发生情况的数据进行了分析。这些结果受2014年家猪业状况的影响尤其大，每增加一个单位的小农场猪密度(小农场动物/平方公里)，观察到ASF阳性的野猪的概率就增加18倍。还有许多其他变量被确定为不显著的危险因素。(详情请见欧洲食品安全局报告)。
The identification of key risk factors at the domestic/wildlife interfacewith a view to strengthening biosecurity and other risk mitigation measures wasa key target of these efforts. In this regard, data of ASF occurrence in wildboar in Estonia, incorporating data from 2014 to 2019, was used for thisanalysis. These results were particularly influenced by the conditions of the domesticpig sector in 2014, presenting an 18-fold increase in the probability ofobserving an ASF-positive wild boar for each unit increase in the density of pigsin smallholdings per local administrative unit (animals in smallholdings/km2). Manyother variables were identified as non-significant risk factors. (Furtherdetails: EFSA report).
Some of the main findings are:
Map 1. Number of ASF outbreaks in European countries since last June
RegardingpotentialriskfactorsforASFoccurrencebutwithaparticularfocusonASFincursionindomesticpigholdingsinRomania,theonlysignificantriskfactorforASFoccurrenceincommercialherds was the distanceto the nearest domestic pigoutbreak.
Drastic reduction (up to 80%) of feral pigpopulations has been reported with control programs in which pig hunting isconducted from a helicopter or through a combination of trapping and intense drivehunting with dogs. Rapid recovery of the population has been reported, up to 77%the year following these interventions. This highlights the fact that urgent interventionsfor disease control (i.e., locally implemented emergency measures) aredifferent from, and should not be confused with, long-term management at larger scale associatedwith sustainable population management.
Fences: Yes or No? - The Belgian experienc
Belgium uses fences as part of the control strategydeployed in the focal outbreak of ASF in wild boar (summary, EFSA report). So far, the measures have proven effective in keeping ASFV within the affected area and avoidingfurther spread. This strategy has included a combination of different measures, namely zoning, carcass removal, a complete feeding ban, specific huntingregulations and depopulation actions depending on the zone, a partial ban of circulation and logging, and setting up a network of concentricfences. Fencing (120 cm high, mesh size 15 x 9 x 20 cm, unburied and not fixxedto the ground) contributed to the slowing down of ASF spread and allowed compartments to be created in which depopulation could be carried out withoutrisking long distance wild boar movements.
Currently, there is no evidence that large fences have been effective forthe containment of wild suids. Some new large-scale fences are under construction,and their effectiveness in separating wild boar populations will need to be evaluatedin the future.
The ASF situation varies substantially between EU countries, due tomultiple influences including the nature of domestic pig production (inparticular, the proportion of backyard holdings), geographic considerations(including topography, natural barriers) and the characteristics of the wild boarpopulation.
Remaining knowledge gaps -
There are significant gaps in knowledge on the epidemiology of ASF in Europe, including:
1. 野猪与死猪尸体的接触率、群体间的接触率、病媒(包括昆虫) 或机械病媒在ASF传播中的潜在作用。
The contact rate between wild boar and carcasses, the contact rate between groups, and the potential role of vectors in ASF spread (including insects) or mechanical vectors.
Regulations should be developed for home slaughtering and appropriate controls enacted, to limit the circulation of infected meat.
To improve wild boar population control strategies, further research is needed:
To clarify the pathways that facilitate ASF persistence in affected areas over a number of years.
To clarify the interpretation of seropositivity in the context of ASF infection, including whether animals that test both PCR negative and Ab positive should be notified as an ASF case or not.
To clarify the ability of survivor animals to excrete or harbor the virus.
To clarify the epidemiological significance of a single, PCR-positive wild boar in areas with no current evidence of infection.
To clarify the duration of colostral antibodies in piglets.
To validate methods to estimate carcass age (time since death) in found-dead wild boar.
To define a pathway to ASF freedom following the detection of the last known infected animal/carcass.
Greece detected the first case of ASF at a backyard farm in the northern part of the country, agriculture ministry officials reported to the OIE on February 6, 2020. The infected finishing farm was confirmed positive near the town Serres, in the province Kentriki Makedonia, a region of northern Greece close to the border with Bulgaria (37.3 miles) and North Macedonia (Map 2).
The farm had 32 pigs, of which one pig had died of ASF. The outbreak was confirmed by the National Reference Laboratory in a dead fattening pig in a backyard farm, using three different diagnostic tests (real-time PCR, ELISA for antigen detection and indirect immunoperoxidase test (IPT)) on February 5. Measures had been adopted in the framework of the suspicion since February 3 and, following the confirmation of the outbreak.
Map 2. Location of the ASF outbreak in Greece
根据欧洲疫情评估报告(DEFRA, UK)的最新信息，从2019年11月到2020年1月31日，保加利亚发生187例野猪ASF疫情。1月份的数据显示疫情高达105例，与之前月份(11月= 44；12月= 38日)相比有所增加。一些病例靠近目前无ASF的北马其顿和希腊边境，这两个国家已经处于高度警戒状态；去年12月，这两个国家被认定为9个巴尔干国家中ASF在一年内最有可能入境的国家(66-100%)。据此，希腊预测将会有ASF爆发，并在确诊该病毒之前加强了监测。
According to the latest updates of the European Outbreak Assessment report (DEFRA, UK), there have been 187 cases of ASF in wild boar in Bulgaria from November 2019 to January 31, 2020. The January count showed a peak of 105 compared to the previous month (November = 44; December = 38), which could suggest an increase in ASF circulation. Some cases were close to the borders of currently ASF- free North Macedonia and Greece, both of which were already on high alert; they had been identified last December, as two of the nine Balkan countries to have a very high chance (66-100%) of disease spread inside their borders within a year of introduction. Accordingly, Greece was expecting an ASF outbreak and had stepped up surveillance, ahead of confirmation of the virus in the country.
Greece produces about a third of its domestic pork consumption and imports the rest. In 2017, the country had about 744,000 pigs (FAO).
All farmed pigs in an area of 3km around the farm were culled. Pigs were not allowed to enter or exit areas within a 10km radius, while tests were being conducted to trace the origin of the disease. Exports of all swine products including meat, food, sperm and eggs, utensils and other related waste from the Serres prefecture was banned. In addition, Serres prefecture veterinarian centers, police, port and government authorities have been placed on alert.
In 2019, Greece submitted to the Commission a program for control eradication of ASF to be implemented in 2020. After its evaluation, the Commission approved the program through a Grant Decision on January 2020 and allocated €203,000 of financial support for the program.
New ASF outbreak on a large commercial farm
The Bulgarian Food Safety Authority (BFSA) has reported an outbreak of ASF in a commercial farm in the village of Nikola Kozlevo, Shoumen District (northeast of the country).
After six months without any new ASF outbreaks on large commercial farms, the National Reference Laboratory in Sofia confirmed the presence of the disease on a pig farm with 24,000 susceptible animals.