African swine fever
Classical swine fever sometimes appears in the news when another outbreak occurs. A lesser known variant of this disease is African swine fever. The symptoms of this virus resemble the classic virus, but are usually much more serious than with the normal virus. The spread of the virus generally takes place in Africa, but the virus has also been detected in Russia and surrounding countries since 2006. Although the symptoms of African swine fever are similar to those of the classical variety, the two viruses are not related.
Every disease has an incubation period. With African swine fever it is two to ten days. Usually the virus comes from the wild. When the virus passes to the pigs that are kept, the mortality rate is often enormous. Sometimes the death rate goes up to 100 percent. This does not apply to all virus strains of the disease. Depending on the different strains, there will often be a mortality between 30 percent and 70 percent. Incidentally, the African virus is much more contagious than the classic virus.
Many of the symptoms are the same as in classical swine fever. This includes fever, weakness, reduced eating behavior, inflamed mucous membranes near the eyes, vomiting, loose stools (diarrhea) and red skin. A number of more serious symptoms can also occur, such as bleeding, bruising, death of parts of the skin and even a miscarriage when carrying a young.
When there is real African swine fever, there will also be bloody diarrhea and a high short-term death rate of the livestock. However, it will often initially be thought that one is dealing with the classic variant of swine fever.
If there is a high mortality rate when it is already clear that there is a variant of swine fever, it may be decided to perform autopsy by the GD (Animal Health Service). A picture is then formed on the dissection table as to whether there really is the African variant of swine fever. Samples of one of the sick animals can also be tested at the CVI (Central Veterinary Institute) in Lelystad.
Traces of the virus can be detected in the blood, spleen, liver, lymph nodes and tonsils of the infected animal. One of those tests is called a PCR. This test searches for genetic material from the virus. With this method, the virus can be detected even when only small amounts of the virus are present. Other possibilities for research are virus isolation and the ELISA-IPMA test. The disadvantage of these tests is that a definite answer can only be given after a few days. With a PCR test this can be done after a few hours.
Fight the disease
No drug has yet been developed to combat African swine fever. The only solution is to clear all animals from the infected farm. As a precaution, the pigs from the surrounding farms are generally also killed.
No vaccine has been developed against African swine fever. Therefore, the pigs cannot be vaccinated to fight the disease. In principle, the Netherlands is free of the African swine fever virus. That is why they are trying to prevent the virus from entering the country. In the event of an outbreak, every possibility of spreading must be counteracted and every threat countered immediately. Rapid detection of the virus is therefore important. The responsibility for this lies largely with the farmer of the pigs.