Early detection and good contingency plans are essential to prevent the entrance of ASF. Risk assessment is a very useful tool for the disease prevention. It allows the identification of regions and risk factors that pose a higher risk for an infectious disease introduction in a free area. Recently, EFSA (European Food Safety Authority) developed a study for the evaluation of ASF introduction in the EU, as well as its potential risk of spread and become endemic in the Caucasus region.
http://www.efsa.europa.eu/en/scdocs/scdoc/1556.htm
Prevention in free areas is based on early detection, proper disposal of waste food from aircraft and ships, and the application of strict sanitary measures of prevention and control. . In the case of ASF the importation of live animals, animal products, semen or embryos from animals in affected areas is banned.
Raw meat products are also totally banned. According to studies carried out, cured products are approved only if they pass a maturation period that can inactivate the virus. Waste food from an affected country, including ship and aircraft waste, must never be dumped but destroyed under hygienic conditions.
On disease-free farms in affected areas prevention must firstly be centred on increasing biosafety measures (DDD programme, controlled access of humans and vehicles, control of all installations (freight platform, fencing, entrance, changing rooms, office, etc.) as well as personnel, water, feed, bedding, residues, carcasses, etc.
Most outbreaks of ASF are caused by purchasing infected animals or feeding infected food waste to pigs. Complete cycle production systems in which the animals are transported directly from the farm where they are born to the abattoir, reduce the risk of spreading ASF. On the other hand, production systems in stages, extensively used at present, facilitate the spread of easily transmissible diseases due to the number of exchanges in each cycle.
There is no treatment or vaccine for ASF, therefore the quality of information and its rapid circulation greatly influence how long the outbreak lasts and the costs incurred.
Once the disease has appeared in an area, control measures must be taken to eradicate it as soon as possible. After the rapid slaughter of all pigs and the proper disposal of their bodies, the cleaning and disinfection of the area, important control measures and biosafety protocols should include:
1. Detailed census with individual identification of all the animals on the affected farm, and a record of any losses.
2. Investigation of movements (of animals, people, food, etc) to and from the affected farm, in a period of time that widely exceeds the incubation period of the disease (at least sixty days).
3. Establishment of two concentric immobilisation areas of 3 and 10 kilometres, respectively, called protection and surveillance zones. This plan of action is followed assuming that the disease has spread due to the proximity of other farms.
4. An epidemiological survey to provide information on the possible origin of the outbreak.
5. Extending the immobilisation area to farms, which, according to the survey, could be the origin of the infection, or could have become infected. Farmers are sometimes tempted not to notify the disease and cull any recovered animals. They assume the low number of losses incurred by the disease in its chronic form to avoid commercial restrictions imposed during the eradication period. The appearance of any pathological process affecting several animals on the same farm at the same time should be treated as suspected ASF and the necessary action must be taken to rule out this possibility.
6. Visits to carry out censuses, identification and clinical inspections, taking the temperature of a large number of animals. Depending on the result, samples are taken as indicated in the section on diagnosis. These control visits should be repeated as often as necessary depending on how the situation evolves (at least once a week), until all of the animals in the immobilised area have passed two clinical and serological controls.
7. Checking for the presence of vectors and carrying out disinsection with effective products and applying the necessary improvements to avoid nesting. Any old stone pigsties should be pulled down or fenced off so that no pigs can enter.
8. The infrastructure of extensive pig farms must be improved so that domestic pigs are kept as far away as possible from wild boars in the area.
European Union has a specific Directive for control of African swine Fever (see pdf)
Stone constructions, possible reservoir of ticks.
ASF can be eradicated if the following actions are taken:
1. Slaughter and hygienic destruction of all pigs on affected farms, and those possibly infected during the incubation period.
2. Elimination of any feed left in the troughs and of beds. Cleaning and disinfection of all fixed and mobile elements that have been in contact with the animals with approved disinfectants.
3. After this, there should be a clearing period of no less than the maximum time the virus can survive in the environment.
4. Once the clearing period has finished and before replacement begins all the farms should be checked for traces of the virus. These tests are carried out with a suitable number of sentinels that are periodically controlled (before entry, and after 30 and 60 days).
On extensive farms the animals should occupy the same areas and buildings as those previously occupied by the infected pigs.
5. The outbreak is eradicated and replacement can go ahead only when all of these measures and controls have been carried out and favourable results obtained.