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No time for complacency
  1. Kathryn Clark

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The summer is over and as the seasonal peak in overseas travel declines, it is easy to think that the associated risk of inadvertent importation of exotic diseases such as African swine fever (ASF) falls away with it.

But this is no time to become complacent. Only this week, the National Pig Association called for Defra and the UK port authorities to take a more robust approach to keeping ASF out of the country and its call is certainly not misplaced. The APHA’s recent disease surveillance report (VR, 7 September 2019, vol 185, pp 259–260) warned that the summer had been ‘a critical time’ for the spread of ASF virus throughout Europe and into other regions through ‘human-mediated routes’. It reported increasing numbers of outbreaks in several European countries, as well as the first outbreaks in Slovakia, and highlighted concern about repeated findings of contaminated products of animal origin in passenger luggage in countries within and outside the EU.

Most recently, the disease has emerged in Serbia, giving rise to concern that the virus will spread to the whole Balkan region.

Anyone doubting the damage that ASF can cause need only look to south-east Asia. An update on the Food and Agriculture Organization’s website on September 12 reported that, since the first confirmed case of ASF in China on 3 August last year, 157 outbreaks had been detected and approximately 1.17 million pigs had been culled in efforts to halt disease spread.

The situation in Vietnam is even more severe – the first outbreak there was confirmed on 19 February 2019 and, since then, 63 provinces and cities have reported outbreaks and more than 4.70 million pigs have been slaughtered. (By way of comparison, statistics from Defra record that there were 4.65 million pigs on agricultural holdings across the UK in December 2018, meaning that Vietnam has slaughtered the equivalent of the entire UK pig population in just seven months.)

That said, the ASF epidemic in Europe is spreading more slowly than the one in Asia, and the structure of the UK pig industry is very different from that in China and Vietnam, with far fewer small-scale backyard pig keepers. Nonetheless, the virus is gradually moving westwards across Europe, the situation being complicated by its presence in wild boar. The overall risk of an incursion of ASF virus to the UK was raised to medium (considered ‘likely’ to occur) in November 2018 and has remained at that level since then, under constant review.

In assessing the risk to the UK, multiple potential entry pathways were considered and, as might be expected, those associated with the entry of meat from restricted areas were associated with greater levels of risk. In an effort to raise awareness of the risk of unwitting importation of the virus in pork products brought in by the travelling public, Defra has been running a campaign at UK ports, airports and train stations, and on social media, over the summer but, as has been pointed out by this journal previously, it is limited in its ability to ban such imports outright (VR, 22 June 2019, vol 184, p 749).

No vaccine is available for ASF

There is also a limit to what could be done to prevent the virus spreading should it reach the UK. No vaccine is available for ASF, although much research is ongoing, including in UK institutes. Until it pays off, and an effective vaccine is developed, tight biosecurity and culling will remain cornerstones of disease control.

Following the foot-and-mouth disease epidemic in the UK in 2001, much effort was put in to drawing up contingency plans for dealing with outbreaks of exotic disease in animals. These plans have been regularly rehearsed and updated ever since, and have been used in dealing with, for example, outbreaks of avian influenza and bluetongue. There is a specific plan for an incursion of ASF – but let us hope that this plan does not have to be put into action for real.

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