African Swine Fever (ASF) is probably the most complex disease among the ones that affect pigs. An illness that made us Spaniards suffer a lot from 1960 to 1995 and that for some years has been very active in Africa and more recently, in Europe, where it is again posing a threat to the pig sector. Despite scientific efforts by different research groups in several countries, we still don’t have a vaccine against this disease, so the main weapons continue to be early detection and rapid implementation of important control measures. To recall some of the most critical points about ASF we have asked some questions that we hope will be of interest.
What happened during all this time without ASF? Why are we now hearing talk about it with such intensity?
Actually, ASF has been around for the past 15 years actively moving through Africa, but its absence outside of Africa (except for Sardinia) caused it to go unnoticed until its return to Europe in 2007. The enormous activity and diffusing capacity of the ASF virus in these years, and its leap to Europe where it has caused global alarm has been caused by three basic facts. First, the increased presence of ASFV in Africa, affecting a larger number of countries (never was the virus present in so many countries and regions of that continent). Second, the increased globalization of markets and communications within Africa and from Africa abroad. Finally, the possible existence of domestic pigs tolerant of the disease, ones that have the virus but no antibodies, an important issue that is currently being investigated in depth, and if confirmed, would explain the presence and movement of a greater volume of potentially contaminated products. If we add to this fact the present situation of global crisis, which encourages the search for other sources of feed supply, including food remains, garbage, etc, we can understand the dimension of the problem.
Is ASF really so dangerous?
ASFV has a relatively limited diffusion capacity especially when compared with FMD, classical swine fever or PRRS. It is moving slowly, but it continues to move forward and it will continue to do so, above all if appropriate control measures are not applied, perhaps affecting wildlife (wild boar) and ticks, with it subsequently becoming endemic.
Figure 2: Current status of PPA in countries of the Caucasus and the Russian Federation. Representation of outbreaks from 2007 to January 2012 in domestic pigs (blue) and boar (red), accompanied by the main risk factors for EU countries (green). Source: WAHID 2012, auto elaboration.
Is it possible that the disease will reach the European Union (EU)?
Yes, indeed it is quite likely given the continuing lack of control and spread of the disease in Russia, including outbreaks in areas very close to the border with the EU. While imports of live pigs and their products are strictly prohibited from the countries concerned, the movement of pigs, illegal trade, vehicles and fomites carried by them, and the existence of joint ventures based in EU countries and Russia make up the main risks to which we must pay attention.
What can we do to prevent or control entry if it takes place?
A key factor in all diseases and even more with ASF, is early detection and rapid implementation of appropriate control measures. To do this, it is imperative that both farmers and swine veterinarians are properly informed of the current risk and the main features of the disease, being able to recognize a possible outbreak and implement appropriate measures in a short period of time, thereby reducing negative consequences. Information is our best tool.
If it entered, would it be easily identifiable?
ASF is a complex disease whose clinical course and symptoms depend on the viral isolate, the dose and route of infection. Furthermore, its symptoms can be confused with other diseases. Therefore the training and warning of farmers and veterinarians is essential. The strain that is currently circulating in Russia and countries of the Caucasus is highly virulent so that the first clinical presentations and acute lesions are what can help raise suspicion of ASF. Definitely, at present the risk of ASF for Europe is the highest since 2007, and we must be prepared, our best defense being information.