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Definition: African swine fever (ASF) is a tickborne and contagious viral disease affecting swine, characterized by fever and high mortality rates, potentially reaching 100%.
History: First described in Kenya, East Africa, in 1921, the disease subsequently affected South Africa and Angola, impacting pig populations of settlers.
Distinction: Meticulous laboratory tests are required to differentiate ASF from classical swine fever (CSF).
Taxonomy: Originally classified under the family Iridoviridae, it is now categorized under the family Asfarviridae.

Understand the general characteristics, morphology, cultivation, pathogenesis, diagnosis, vaccines, and control measures associated with ASF.

Classification: Group I double-stranded DNA viruses.
OIE Listing: Classified as List A infection denoting priority for control and monitoring.
Risk Group: No associated human infection with ASFV.

Structure: Virions are complex, composed of an envelope, a capsid, a core, and a nucleoprotein complex.
Physical Attributes:
- Diameter: Spherical virions measure between 175 to 215 nm.
- Capsid contains 1892-2172 capsomers, each with a diameter of 13 nm.
- Genome: Single molecule of linear double-stranded DNA not segmented, with lengths ranging from 170,000 to 190,000 nucleotides.
- Capsomer Composition: Each capsomer features a hexagonal base with a central cavity.

Entry: Virus enters host cells via endocytosis.
Uncoating occurs within the cytoplasm.
DNA Transport: Viral DNA transported to the nucleus where transcription commences using host RNA polymerase II.
Genome Replication: Host cell's replication machinery is utilized for producing viral progeny.
Assembly and Exit: Progeny DNA returns to the cytoplasm for assembly; viruses exit through budding or cell lysis.

Affected Hosts: Includes domesticated pigs, warthogs, bush pigs, European wild boar, and American wild pigs.
Distribution: Enzootic in most Sub-Saharan African nations and some parts of Europe, although it has been eradicated in many regions, and is not reported in India.
Transmission: Via both direct contact (sick to susceptible animals) and indirect means (contaminated feed, vectors like Ornithodoros ticks, fomites). Initial infection in herds often arises through indirect methods with subsequent internal spread facilitated by direct means.
Incubation Period: Very short, ranging from 48 to 72 hours.
Morbidity and Mortality: 100% morbidity in unexposed herds. Mortality rates vary by virulence, with highly virulent strains causing nearly 100% mortality, while less virulent isolates may lead to 60-70% mortality.

Clinical forms range from peracute, acute, subacute to chronic. Symptoms appear 5-15 days following infection with ASF virus.
Initial Signs: High fever (41-42°C), depression, loss of appetite, seeking shelter, huddling, rapid breathing, and potential flushing of skin (notably in white-skinned pigs).
Further Manifestations: Weak hind legs, clear or blood-tinged discharge from nose and eyes, difficulty breathing with potential foam at nostrils, abdominal pain, vomiting, and either constipation or bloody diarrhea.
Reproductive Impacts: Abortions may occur at any pregnancy stage.
Skin Symptoms: Flushing of skin that may progress to a bluish-purple coloration, signs of hemorrhage, and congested mucous membranes.
End Stage: Coma may arise from hemorrhagic shock or lung fluid before death, typically occurring 1-7 days after symptoms onset.
Chronic Symptoms: Weight loss, dull fur, possible lesions, arthritis, with variable survival periods post-initial acute phase.

Based on clinical signs and lesions; differentiating from classical swine fever is often challenging.

Materials for Isolation and Identification: Heparinized blood, clotted blood, serum, lymph nodes (submandibular, inguinal, tonsil), spleen, liver, lung, kidneys, and bone marrow.
Identification Systems: Virus presence detected via haemadsorption when red blood cells adhere to infected cells in culture.
PCR and Immunofluorescence: Used for confirmation of virus in clinical samples.

Enzyme-linked immunosorbent assay (ELISA) is predominant for antibody detection against ASF in serum. Other tests include immunofluorescence and immunoblotting. Notably, antibodies may not be detectable in pigs that succumb to acute ASF.

Important to differentiate ASF from CSF, Swine erysipelas, Salmonellosis, and Pasteurellosis.

Vaccination: No available vaccines against ASF.
Eradication:
- In ASF-free countries:
- Carefully manage importation of animals and products.
- Thorough waste disposal protocols for incoming goods.
- Effective sterilization of potentially infected waste.
- During outbreaks:
- Prompt slaughter of all affected pigs.
- Thorough sanitation and disinfection procedures.
- Establish quarantined zones with monitored movements of pigs.
- Conduct epidemiological investigations to trace sources and prevent further spread.
- Continuous surveillance of both infected and surrounding areas.
- In infected countries:
- Prevent interaction of pigs with potential tick vectors.

Etymology: The Greek origin of “herpes”, meaning "to creep", indicative of the chronic infections caused by these viruses in both humans and animals.
Family Characteristics: The family Herpesviridae encompasses approximately 100 members, divided into three sub-families:
- Alphaherpesvirinae
- Betaherpesvirinae
- Gammaherpesvirinae