A highly contagious disease, African Swine Fever (ASF) spreads primarily through pigs and ticks. It is endemic to some parts of Africa and thus, the name.
African Swine Fever Virus (ASFV), which causes this infectious disease, belongs to the Asfivirus genus of the Asfarviridae family. It generally affects species like the European wild boar, peccaries, feral pigs, warthogs, giant forest hogs, and domesticated pigs. The effects of the same may vary in intensity, but most of the pigs die within a few days of infection.
Transmission of Disease
The virus mainly spreads through their mouth and nose. Even ticks carry out the dissemination of this virus. The blood of an infected pig that is injured during a pig fight, can also cause the virus to spread. At times, the food given to pigs gets mixed with leftovers of an infected pig, which eventually leads to transmission of this virus to healthy individuals. Contaminated sites can hold the virus for up to one month. Blood, feces, salted dried ham, frozen carcass, and boned meat are other mediums through which the virus is transmitted.
Signs and Symptoms
The symptoms of this condition start surfacing within 5 – 7 days of infection. These include …
- Peracute: It is caused by strains of virus that are highly virulent. It results in 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: Other than high fever, this form of African Swine Fever is characterized by 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. In this form of disease though, the intensity or severity of 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.
The virus isolation technique is used for the diagnosis of 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 pigs.
Prevention and Control
It can be prevented by implementing the following action plan.
- The food given to the pigs should be cooked beforehand to prevent the transmission of the virus.
- Unprocessed meat needs to be heated for 30 minutes at a temperature of 70°C 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. It is very important to dispose the carcass properly. Sodium hypochlorite and other such disinfectants can be used to prevent further spread of the disease.
History of the Disease
This disease is endemic to some sub-Saharan regions of Africa. The region between the equator and northern Transvaal has seen major outbreaks of this disease. Sporadic incidences of African Swine Fever outbreak have occurred outside the sub-Saharan region. The disease is also prevalent outside Africa; in Sardinia, Italy, in particular, where it is mostly found in wild pigs.
The mortality rate of pigs in case of African Swine Fever is quite high. Young pigs are more vulnerable to this disease than adults. No vaccine is available for this disease and thus, it inflicts great economic losses on the owners of pigs. Thankfully, humans are not susceptible to this disease.