Lecture 21 - Enteroviruses
1. Identificaction
- Viruses that live in the GI tract
- Belong to picornavirus family
- Polio, Coxsackie Type A, Coxsackie Type B, Echovirus, and Enterovirus
2. Encounter/Entry
- Secreted in large amounts in stool, therefore acquired by fecal/oral route
- Often occur in summer or early fall in temperate climates
3. Spread/Multiplication
- Virus is ingested, replicates in lymphoid tissue of the pharynx and/or small intestine, and transient viremia causes mild illness
- If viremia persists, major viremia develops and can spread to distant organs causing severe disease
4. Damage
4.1. Poliovirus
- Replication is accompanied by destruction of infected host cells
- Can spread hematogenously from GI tract to CNS where it replicates in grey matter neurons
- Anterior horn cell destruction manifests as flaccid paralysis of limb muscles
- Bulbar poliomyelitis can cause paralysis of respiratory muscles
4.2. Coxsackie A and B, Echovirus and Enterovirus
- Can cause asymptomatic or mild febrile infections, respiratory symptoms, rashes, or aseptic meningitis
- Coxsackie A can cause herpangina, a mild self-limiting disease that manifests as fever, sore throat and small red-based vesicles on the back of the throat
- Coxsackie B can cause pleurodynia characterized by fever, headache and severe pleuritic pain
- Also causes myocarditis and pericarditis 50% of the time
4.3. Key Virulence Factors
- Spread from GI tract to distant organs due to presence of specific receptors on the membranes of target cells
4.4. Diagnosis
- Epidemiological history is key
- Requires isolation from involved site
- Serological tests not necessary because enteroviruses do not share common antigens
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