Taxonomy and Biological Properties of the Pathogen
The foot-and-mouth disease agent belongs to the Picornaviridae family and is classified into its own genus, Aphthovirus. Genetically, it is an RNA-containing virus. The classification of the pathogen recognizes a single species, which is nevertheless represented by seven distinct serotypes. In its morphological characteristics and chemical composition, the foot-and-mouth disease virus bears significant similarity to other members of the picornavirus group.
A key feature of the pathogen is its high virulence. The virus exhibits a pronounced dermatotropism—the ability to selectively target cells of the skin and mucous membranes, causing localized defects.
Regarding stability, Aphthovirus can remain viable in the external environment and in contaminated food products for prolonged periods, lasting several weeks. Despite this, the virus exhibits high susceptibility to chemical disinfectants, making their application an effective method for eliminating the pathogen from surfaces.
Epidemiology of Infection
Foot-and-mouth disease is a classic zoonosis. The primary reservoir and source of infection in nature are infected animals. Primarily cattle, though pigs, small ruminants, and rodents can also become involved in the epidemiological process.
Infected animals actively shed viral particles into the external environment through various biological secretions, most notably milk, saliva, and urine.
There are two main mechanisms of transmission to humans:
- Contact route: realized primarily through direct handling of infected farm animals.
- Alimentary route: infection is transmitted by consuming raw milk or dairy products derived from infected livestock that have not undergone thermal processing.
Despite the variety of transmission routes, natural human susceptibility to the foot-and-mouth disease virus is considered low.
Clinical Presentation in Humans
Because the virus exhibits marked dermatotropism, the clinical presentation in an infected human features highly specific, easily recognizable traits. The disease unfolds with a pronounced febrile state.
The key and most striking symptom is the formation of aphthae—characteristic ulcerative lesions. These are most commonly localized on the oral mucosa, as well as on the skin of the patient's hands and feet.
Laboratory Diagnostics and Prevention
To confirm the diagnosis, specific clinical material is sent to the laboratory: aphthous contents, saliva, or the patient's blood.
Laboratory diagnostics rely on the following methods:
- Biological method: involves experimental inoculation of laboratory animals (traditionally guinea pigs and suckling mice). An alternative is introducing the material into susceptible cell cultures for subsequent viral isolation.
- Serological method: based on testing paired patient sera to detect antibody dynamics. Various serological reactions are used for this purpose: CFT (complement fixation test), NT (neutralization test), IHA (indirect hemagglutination assay), and ELISA (enzyme-linked immunosorbent assay).
Prevention of foot-and-mouth disease in humans is exclusively non-specific. Specific vaccines are not used for humans; protection is based on adhering to sanitary and hygienic standards when handling animals and properly heat-treating milk.