Theoretical basis for systemization of differential diagnosis of African swine fever

Abstract

African swine fever (ASF) poses a global threat to pig production characterized by high contagiousness and a mortality rate approaching 100%. The causative agent is a DNA virus of the Asfarviridae family which unique feature is the lack of induction of virus-neutralizing antibodies that nullifies the natural immune response and greatly complicates disease control. A key diagnostic challenge remains the significant clinical and pathological similarity of ASF to other dangerous infections as classical swine fever (CSF), erysipelas, Aujeszky’s disease, salmonellosis, and pasteurellosis. The research goal was a comprehensive analysis of epizootological, clinical, and pathological criteria for systemization of differential diagnosis of ASF. Particular attention is paid to comparison to CSF, as it is the most similar disease. Key distinguishing features include the rapid spread and 100% mortality of African swine fever (ASF) versus the slower progression and lower mortality of CSF as well as specific pathological changes (hemorrhagic lymph nodes resembling a “blood clot,” extensive renal hemorrhages, and serous-hemorrhagic pneumonia). African swine fever differs from other diseases, in particular, by the lack of seasonal pattern (unlike erysipelas and salmonellosis), its ability to affect animals of all ages (unlike Aujeszky’s disease and salmonellosis), and its pronounced hemorrhagic diathesis. Despite the developed preliminary diagnostic algorithm based on analysis of the epizootic situation, clinical manifestations, and pathological findings, a definitive diagnosis of ASF may only be established by laboratory methods, primarily real-time PCR. Until a commercial vaccine is developed, strict biosecurity measures, early detection and immediate eradication of outbreaks remain the basis for disease control.