Contents
More recently, a new disease has appeared – African swine fever literally knocks down all private pig production in the bud. Due to the very high contagiousness of this virus, veterinary services are forced to destroy not only the sick livestock, but also all healthy pigs in the area, including wild boars.
Origin of the disease
African swine fever virus (ASF) is a natural focal disease affecting wild pigs in Africa. The ASF virus remained there until the beginning of the XNUMXth century, until the white colonists decided to bring European domestic pigs to the African continent. The “natives” of Africa in the process of evolution have adapted to the virus of African swine fever. In them, the ASF virus persisted in a chronic form within the family herd. This virus did not bring much harm to warthogs, bushy-eared and large forest pigs.
Everything changed with the appearance on the African continent of the European domestic pig, descended from the wild boar. It turned out that the European representatives of the pig family have zero resistance to the ASF virus. And the virus itself has the ability to spread rapidly.
The ASF virus was first isolated in 1903. And already in 1957, the victorious march of the virus across Europe began. The countries located near Africa were the first to be hit: Portugal (1957) and Spain (1960). It turned out that in European pigs, African swine fever instead of a chronic one takes an acute course with a 100% fatal outcome in case of clinical signs.
What is the danger of African swine fever
From the point of view of the danger of the ASF virus to humans, African swine fever is completely safe. The meat of sick pigs can be safely eaten. But it is in this safety for people that the serious danger of the ASF virus for the economy lies. And this is due to the fact that you can spread the virus without knowing it. The ASF virus, which is not dangerous to humans, causes enormous losses in the pig industry. At the beginning of the victorious march of the African plague virus, it affected:
- Malta (1978) – $29,5 million;
- Dominican Republic (1978-1979) – about 60 million dollars;
- Cote d’Ivoire (1996) – $32 million
In the Maltese archipelago, the total destruction of the pig population was carried out, since due to the size of the islands it was not possible to introduce quarantine zones. The epizootic resulted in a ban on keeping pigs in private homes. The fine for each specimen found is 5 euros. Pigs are bred only by entrepreneurs on specially equipped farms.
Propagation paths
In the wild, the ASF virus is spread by blood-sucking ticks of the ornithodoros species and wild African pigs themselves. Due to the resistance to the virus, wild African pigs can act as peddlers when in contact with domestic ones. “Africans” may be sick for several months, but shed the ASF virus into the environment only 30 days after infection. After 2 months after infection, active ASF virus is found only in the lymph nodes. And infection with the causative agent of African swine fever can occur only through direct contact of a sick animal with a healthy one. Or by transmission of the virus by ticks.
In the conditions of pig farms and private farms, everything happens differently. In soil contaminated with faeces, the virus remains active for more than 100 days. The same applies directly to manure and chilled meat. In traditional pork products – ham and corned beef – the virus is active for up to 300 days. In frozen meat, it lasts up to 15 years.
The virus is shed into the environment with feces and mucus from the eyes, mouth and nose of sick pigs. On walls, inventory, boards and other things, the virus remains active for up to 180 days.
Healthy pigs become infected through contact with infected animals and their carcasses. The virus is also transmitted through feed (it is considered especially beneficial to feed pigs with waste from public catering establishments), water, transport, and equipment. If all this is contaminated with the faeces of plagued pigs, infection is guaranteed to the healthy.
Since the virus is not dangerous to humans, when signs of African plague appear, it is more profitable not to notify the veterinary service, but to quickly slaughter pigs and sell meat and lard. This is where the real danger lies. It is not known where the products will end up after the sale and where the next plague will break out due to the fact that a half-eaten piece of infected salted fat was fed to pigs.
Symptoms of ASF
Signs of African swine fever and erysipelas in pigs are very similar and laboratory testing is required for accurate diagnosis. This is another reason why the elimination of ASF outbreaks is very difficult. It is very problematic to prove to a pig breeder that his animals have ASF and not erysipelas.
For the same reason, there are no videos with signs of African swine fever. No one wants to draw the attention of the veterinary service to their farm. You can only find a video with a verbal story about the signs of ASF in pigs. One of these videos is shown below.
As in the case of erysipelas, the form of ASF is:
- lightning fast (super sharp). The development of the disease occurs very quickly, without the manifestation of external signs. Animals die in 1-2 days;
- sharp. Temperature 42°C, refusal to feed, paralysis of the hind legs, vomiting, shortness of breath. Difference from erysipelas: bloody diarrhea, cough, purulent discharge not only from the eyes, but also from the nose. Red spots appear on the skin. Before death, falling into a coma;
- subgrade Symptoms are similar to the acute form, but are milder. Death occurs on the 15-20th day. Sometimes a pig recovers, remaining a virus carrier for life;
- chronic. Has an asymptomatic course. It is very rare in domestic pigs. Basically, this form is observed in wild African pigs. An animal with a chronic form is a very dangerous carrier of the disease.
When comparing the symptoms of swine erysipelas and ASF, it can be seen that the symptoms of these two diseases differ little from each other. Photos of pigs that died from African plague also differ little from images of pigs with faces. For this reason, laboratory tests are needed to accurately diagnose the disease.
The photo shows signs of African swine fever. Or maybe not ASF, but classic. You can’t figure it out without microbiological research.
Laboratory diagnosis of African swine fever
ASF must be differentiated from erysipelas and classical swine fever, so the diagnosis is made in a complex manner based on several factors at once:
- epizootological. If there is an unfavorable ASF situation in the area, animals are more likely to get sick with it;
- clinical. Symptoms of the disease;
- laboratory research;
- pathological data;
- bio samples.
The most reliable way to diagnose ASF is to use several methods simultaneously: the hemadsorption reaction, PCR diagnostics, the method of fluorescent bodies and a bioassay on piglets immune to classical plague.
A highly virulent virus is easy to diagnose, since in this case the lethal outcome among diseased animals is 100%. Less virulent strains of the virus are more difficult to identify. Suspicion at autopsy should be caused by pathoanatomical changes characteristic of African swine fever:
- greatly enlarged spleen dark red. May be almost black due to multiple hemorrhages;
- enlarged 2-4 times the lymph nodes of the liver and stomach;
- similarly enlarged hemorrhagic lymph nodes of the kidneys;
- numerous hemorrhages in the epidermis (red spots on the skin), serous and mucous membranes
- serous exudate in the abdominal and chest cavities. May be mixed with fibrin and blood
- pulmonary edema.
African swine fever genotyping is not done for diagnosis. Other scientists are doing this, using wild African livestock.
Instructions for the eradication of African swine fever
Measures to eliminate the outbreak of African swine fever are carried out by veterinary services. According to the international classification, African swine fever has been assigned hazard class A. All that is required of the pig breeder is to notify the service about the animal disease. Further, the veterinary service acts according to the official instructions, according to which quarantine is introduced in the region with the total slaughter of all pigs and posts on the roads in order to prevent the possible export of infected pork to other regions.
The entire herd on the farm where ASF is found is slaughtered by the bloodless method and buried at a depth of at least 3 m, sprinkled with lime, or burned. The entire territory and buildings are thoroughly disinfected. No animals will be allowed to be kept at this place for another year. Pigs should not be kept for several years.
All piglets are seized and destroyed from the population within a radius of several kilometers. There is a ban on keeping pigs.
It should be borne in mind that some porous materials cannot be fully disinfected and the virus can exist there for a long time. Materials undesirable for the construction of a pigsty:
- tree;
- brick;
- foam blocks;
- claydite blocks;
- adobe brick.
In some cases, it is easier for the veterinary service to burn the building than to decontaminate it.
Prevention of ASF
In order to guarantee the prevention of the occurrence of ASF in a personal household, certain rules must be observed. In pig breeding complexes, these rules have been elevated to the rank of law, and it is easier to follow them there than in a personal farmstead. After all, a pig-breeding complex is a place of work, not a place of residence. However, unsanitary conditions cannot be bred in household plots.
Rules for the complex:
- do not allow free range of animals;
- keep piglets indoors;
- regularly clean and disinfect places of detention;
- use a change of clothes and separate equipment for caring for pigs;
- buy food of industrial origin or boil food waste for at least 3 hours;
- exclude the appearance of strangers;
- do not buy live pigs without a veterinary certificate;
- move animals and pork without the permission of the state veterinary service;
- register livestock in local administrations;
- do not slaughter animals without ante-mortem inspection and sell pork without a sanitary examination of meat;
- do not buy pork “from hand” in places not designated for trade;
- do not interfere with the veterinary examination and vaccination of pigs;
- carry out the disposal of corpses and biowaste only in places determined by the local administration;
- do not process for sale the meat of forcedly slaughtered and dead animals;
- in the habitats of wild boars, do not use water from streams and calm rivers for watering animals.
If you remember how the population complies with all these rules, you get about the same picture as in the video below.
Is African swine fever dangerous to humans?
From a biological point of view, it is completely safe. It is very dangerous for the nerves and wallet of the pig owner. Sometimes ASF is also dangerous for the freedom of the perpetrator of an ASF outbreak, as failure to comply with the above rules can lead to criminal liability.
Conclusion
Before you get a piglet, you need to check with the veterinary service the epidemiological situation in the area and whether it is possible to get pigs. And you should always be prepared for the fact that at any moment an ASF outbreak may appear in the area, because of which the animal will be destroyed.