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| How ASF Spreads |
#15,490
Although the world remains fixated on our COVID-19 pandemic and possible interactions with the upcoming Northern Hemisphere flu season, there are other disease threats in the wild that are worthy of our attention.
Sadly, much of the (already limited) surveillance and reporting we were getting before COVID-19 appeared, has either vanished or has been sharply curtailed (see Flying Blind In the Age Of Pandemics & Emerging Infectious Diseases).
It has now been 4 months since the Saudi MOH last updated their daily MERS-CoV surveillance website, and 8 months since the last monthly update from the WHO EMRO (Eastern Mediterranean Regional Office).
The World Health Organization did publish a DON report in early July (see WHO DON: Middle East respiratory syndrome coronavirus (MERS-CoV) – Saudi Arabia), which provide details on the cases reported in May. No other Middle Eastern countries have reported any MERS-CoV cases since March.
Prior to the emergence of SARS-CoV-2, MERS was considered to be the coronavirus with the greatest pandemic potential (see Study: A Pandemic Risk Assessment Of MERS-CoV In Saudi Arabia). While beaten to the finish line, it could still place or show.
Similarly, we've seen a huge drop off in influenza surveillance and reporting - both for seasonal flu, and novel influenza viruses. All summer, the WHO Influenza report has carried a disclaimer:
The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic have influenced to varying extents health seeking behaviours, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. The various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 virus.
While diseases that directly infect and harm humans are our top priority, agricultural diseases can have a huge impact on food insecurity, local and global economies, and even political and social stability.
Although we've gotten recent reports of avian flu outbreaks from Russia and Kazakhstan (see FLI: Risk Assessment Of HPAI H5 Affecting Germany This Fall & Winter), we've heard almost nothing from China since the spring.
China has been equally silent on their African Swine Fever (ASF) outbreak, which by some reports may have killed half of all the pigs in China over the past two years. The UN FAO's most recent update on ASF in Asia was released on March 5th, with the next update promised in 2 weeks time.
Although ASF doesn't infect humans, it is generally 100% fatal in pigs, and there is no vaccine or treatment available. The only solution is to cull infected (or exposed) pigs.Given the pandemic driven supply chain issues, and warnings of increased food insecurity around the world (see Poverty and food insecurity could grow dramatically as COVID-19 spreads), anything that further depletes or stresses the global food supply is a serious concern.
So far, Western Europe, Australia, and North and South America have been spared - but continued success is far from certain.A year ago the USDA announced enhanced testing and surveillance for ASF in American pigs, in hopes of detecting - and stamping out - any infections as early as possible. Also last year, in Nature Sci. Rpts: Risk of African Swine Fever Virus Introduction into the United States, we looked at a study that attempted to quantify the risks ASF arriving in North America.
One of the few ASF affected areas of the world where we do get timely surveillance data is Eastern Europe, where the virus has been steadily spreading - and slowly creeping westwards towards Central Europe - for a decade.
The UK's DEFRA (Department for Environment, Food and Rural Affairs) continues to provide us with regular updates on ASF's, with their latest installment published this week, which highlight new incursions of the virus into Germany.
Updated Outbreak Assessment #16
African swine fever in Europe (Eastern Europe and Germany)
2 October 2020
Ref: VITT/1200 ASF in Europe (Eastern Europe and Germany)
Disease report
This is a short update on the spread of African swine fever (ASF) in wild boar in Germany since our last report on 17 September. The map below shows the locations of the ASF cases in wild boar in eastern Germany and Poland, together with the outbreaks in domestic pigs in Poland reported from January to end of September 2020. Of note, ASF is moving north in wild boar both in eastern Germany and in western Poland, albeit ~150 km apart.
Situation assessment
The total number of confirmed cases of ASF reported in Germany to the end of September is now at 38, since the first report on the 10 September. All are in wild boar (either shot or found dead) in the State of Brandenburg, with no domestic pig farms affected so far. However, the virus has been identified further north along the Germany/Poland border and there are now two separate outbreaks in the State of Brandenburg (see map).
On 29 September an infected wild boar was shot some 60 km north of the first outbreak, where the other 37 cases have all occurred. Of these, 28 were found in the Oder-Spree district and nine in the Spree-Neisse district (Pig Progress 2020a). The 37 cases are all located between a few hundred metres and up to 6 km from each other inside a core area of 150 km 2 , which was established and provisionally fenced on 12 September. The new case was near the hamlet of Bleyen in Märkisch-Oderland district and is about 2 km from the border with Poland (Lehmann, 2020, Lehnert, 2020). The boar was a young one (< 1 year) and with a pack of 10 – 15 wild boars in a corn field. Post mortem examination showed pathology of organs indicative for ASF which was confirmed by PCR. The low Ct values indicated a high virus load. More ASFV-positive boar are expected to be found and surveillance of domestic pig holdings has not detected anything suspicious.
The location of the infected wild boar in Märkisch-Oderland is notable in that there have not been any reports of infected wild boar on the other side of the border in Poland at this latitude (see map). This new case represents a geographical jump similar to that as for the first German ASF case in wild boar (decomposed carcase of an infected female) at Oder-Spree, found on the 9 September, with the nearest known ASF detection being in Poland located some 30 km away (see previous Outbreak Assessment). For that first case reported in Germany, the geographical jump of 30 km could be explained by male wild boar travelling that large distance, although this is less likely for a female wild boar.
Alternatively, the carcass of an infected animal that may have floated down the Oder River is another possibility for the source of infection (Pig Progress 2020a). The border between Poland and Germany runs from north to south and is formed by two rivers. In the south, this is the Neisse River, which extends from south of Eisenhüttenstadt and joins the larger Oder River. The Oder then forms the border river until it reaches the Baltic Sea in the north. The first group of ASFV-infected wild boar in Germany were found at exactly the same latitude as the confluence of these two rivers (Pig Progress 2020a), suggesting that transmission via the waterway was a distinct possibility.
(SNIP)
Conclusion
In Germany, ASF in wild boar has been reported some 60 km further north along the border with Poland with the finding of a positive wild boar shot at the end of September.
This is not near to any wild boar cases in Poland, where ASF is also moving north in wild boar, albeit 150 km directly east of the German case. Poland is still reporting high numbers of ASF outbreaks in domestic pigs. ASF is still present in wild boar across much of Eastern Europe. Therefore, there still remains a risk of entry of ASF virus in products of animal origin from affected countries, including from illegal imports.
The current risk of ASF being introduced into the UK through the entry of contaminated or infected pork or pork products, remains at medium.
All travellers are strongly advised to avoid bringing any pork products – for example, dried or cured meats, sausages, salamis or pâté – back to the UK from affected parts of Europe.
Travellers from Asia and other third country areas who bring meat or dairy products can also face prosecution and a large fine.
We would like to emphasise to all pig keepers, pig producers, smallholders and general public to ensure pigs are not fed catering waste, kitchen scraps or pork products, thereby observing the swill feeding ban.
All pig keepers should remain vigilant and ensure that any visitors to their premises have not had any recent contact with pigs or pig premises in the affected regions. People returning from any ASF-affected areas of the world should avoid any contact with domestic pigs in commercial holdings, smallholdings or even household pet pigs. Habitats where feral pigs or wild boar exist should also be avoided. All clothing, footwear or equipment should be disinfected before entering pig areas.
Pig keepers and veterinarians should remind themselves of the clinical signs for ASF. Any suspect cases must be reported promptly. Please see https://www.gov.uk/guidance/african-swine-fever for more information
Although ASF has never been reported in North America, the potential for seeing it here someday is quite real, and the costs to agricultural interests could run into the billions of dollars.
The USDA takes this threat seriously, and last month published the following brief update on their containment plans should the virus be detected in the United States.
