General Characteristics and Taxonomy
Both groups of pathogens belong to the family Picornaviridae and the genus Enterovirus. They are compact RNA viruses, each comprising over 30 distinct serotypes.
The name Coxsackievirus is geographical, derived from the American town where the pathogen was first discovered and isolated.
The acronym ECHO stands for Enteric Cytopathogenic Human Orphan virus. The fundamental difference between ECHO viruses and Coxsackieviruses is that ECHO viruses are non-pathogenic to laboratory animals.
Coxsackieviruses: Groups A and B
Historically, the classification of Coxsackieviruses is based on their ability to cause specific pathological changes in newborn suckling mice. Based on these manifestations and clinical presentations, they are divided into two main groups.
Group A (Coxsackievirus A) Predominantly affects mucous membranes, skin, and skeletal muscles, causing focal necrosis and diffuse myositis. Characteristic clinical forms include:
- Herpangina: formation of herpetiform vesicles on the posterior pharyngeal wall, accompanied by fever and dysphagia.
- Hand, foot, and mouth disease (vesicular stomatitis with exanthem).
- Diarrhea is frequently observed in children.
- Skin rashes (exanthem) and poliomyelitis-like neurological diseases may occur.
Group B (Coxsackievirus B) Characterized by pronounced tropism for the central nervous system, visceral pathology (internal organ involvement), and skeletal muscle necrosis. Typical manifestations include:
- Bornholm disease (pleurodynia): excruciating chest pain attacks, fever, and pleuritis.
- Myocarditis (severe inflammation of the heart muscle).
- Neurological pathologies: encephalitis, paralysis, and poliomyelitis-like states.
ECHO Viruses
Since ECHO viruses do not infect laboratory animals, their study and cultivation are performed exclusively in cell cultures.
The clinical presentation of ECHO virus infections is highly variable and may include:
- Acute respiratory viral infections (ARVI).
- Aseptic viral meningitis.
- Diseases mimicking poliomyelitis.
- Various forms of skin rashes.
Microbiological Diagnostics
Specimens for enterovirus detection include feces and nasopharyngeal swabs. When central nervous system involvement is suspected, particularly in ECHO virus infections, cerebrospinal fluid (CSF) is additionally analyzed.
- Virological method (pathogen isolation):
- For Coxsackieviruses, the classical method involves inoculating suckling mice followed by analysis of pathological tissue changes.
- Coxsackieviruses B, certain Coxsackieviruses A serotypes, and all ECHO viruses are successfully isolated by inoculating cell cultures (e.g., HeLa cells or monkey kidney cells).
- Serological method:
- Based on detecting a rising titer of specific antibodies in paired acute and convalescent sera.
- Identification:
- Serotyping is performed using standardized assays: hemagglutination inhibition (HAI), complement fixation test (CFT), neutralization test (NT), and ELISA.