African Swine Fever

The African swine fever virus, which causes the infectious disease, comes from the Asfivirus genus of the Asfarviridae family. The virus affects the pigs in varying degrees of intensity. In most cases, the pigs die within a few days of infection.

Victims of the Disease
The African swine fever affects various pigs of the 'Suidae' family. It includes the European wild boar, peccaries, feral pigs, warthogs, giant forest hogs and domesticated pigs.

Disease Transmission
The disease spreads mainly through the mouth and nose of pigs. Ticks also carry out the dissemination of the virus. During pig fights, the pigs may get injured and the blood can also spread the virus. Sometimes, the food given to pigs gets mixed with left overs of the infected pork. It can lead to the transmission of the virus. Contaminated pigs sties can hold the virus for up to one month. Blood, feces, salted dried hams, frozen carcasses and boned meat are a few more mediums through which the virus is transmitted.

Symptoms and Signs
The infected pigs show the symptoms of the disease within 5-7 days. The African swine fever can affect pigs in varying degrees. The different forms of the disease are as follows.

• Peracute: The peracute fever is caused by strains of virus that are highly virulent. It results in the sudden death of pigs. Formation of lesions on the body is one of the main characteristics of peracute fever. This form of the disease can wipe out the entire herd in just a few days.
• Acute: Along with high fever, other symptoms of acute fever are lethargy, anorexia, erythema and recumbency. Abdominal pain, diarrhea and vomiting are few more signs of acute fever.
• Subacute: The symptoms of subacute fever are similar to acute fever. However in this form of the disease, the intensity or severity of the symptoms is lesser than that in acute fever.
• Chronic: In chronic fever, diarrhea, vomiting and coughing are the commonly observed symptoms. It may also lead to loss of appetite and depression in pigs.

Diagnosis
The virus isolation technique is used for diagnosis of the African swine fever. Samples of blood and tissue from the affected animal are collected and inoculated into special cultures, for isolation of the virus. A test called 'Autorosette Test' can also be used to detect the virus in affected pigs.

Prevention and Control
The African swine fever can be prevented by implementing the following action plan.

• The food given to the pigs should be cooked beforehand to prevent the virus transmission.
• The unprocessed meat needs to be heated for 30 minutes at a temperature of 70^oC in order to avoid any kind of contamination.
• Quarantine measures at airports, harbors, docks, etc. should be strictly followed.

The disease can be controlled by slaughtering and burying the infected pigs. Disposing off the carcasses is also necessary. Disinfectants such Sodium hypochlorite are used to prevent further spreading of the disease.

History of African Swine Fever
The African swine fever is an endemic disease in some sub-Saharan regions of Africa. The region stretching between the equator and the northern Transvaal has seen major outbreaks of this disease. Sporadic incidences of the African swine fever have occurred outside the sub-Saharan region. The disease is also prevalent outside Africa in Sardinia, Italy. The disease here, is endemic in its form and mostly found in wild pigs.

The mortality rate of pigs in case of the African swine fever is quite high, so it is considered a fatal disease. Young pigs are more vulnerable to this disease than the adult ones. There is no vaccine available for this disease; hence it inflicts great economic losses on the owners of pigs. Thus, preventing the disease remains the only option. Another important thing to remember is that human beings are not susceptible to the African swine fever.