*3.2.4. African Swine Fever Virus (ASFV)*

The African swine fever virus is the causative agent of the african swine fever (ASF), that is a highly contagious and lethal disease characterized by a clinical picture similar to that of the classical swine fever [61, 62]. The epidemiological characteristics of the disease include the potential for rapid dissemination through direct and indirect contact as well as a natural transmission via arthropods and wild Suidae.

The virus of the African swine fever was isolated from the semen of infected pigs [6, 57]. The virus elimination through bodily secretions can last up to 70 days in persistently infected an‐ imals [63], which are the main villain in dissemination of the virus in herd.

Besides the epidemiological importance, the persistently infected animals are the major ob‐ stacle to diagnosis because they present less severe clinical signs, as requiring confidential laboratory tests in order to establish a reliable definitive diagnosis of ASF as well as to pro‐ vide relevant information about the time of infection in order to successfully support the control and eradication programs [64]. The viral isolation is an important tool for diagnosis, however it is a laborious and very slow procedure. The PCR technique has good sensitivity and specificity and is a faster alternative for detection of the virus [61].

Because of the unavailability of the vaccine against ASFV, the control strategies involve circulation restrictions, biosecurity and stamping out [65]. In Spain, the successful ASF eradication has been associated with the screening and removal of the persistently infect‐ ed pigs [66].
