Tufts OpenCourseware
Search
Author: Amelia Virostko

1. Identificaction

  1. Viruses that live in the GI tract
  2. Belong to picornavirus family
  3. Polio, Coxsackie Type A, Coxsackie Type B, Echovirus, and Enterovirus

2. Encounter/Entry

  1. Secreted in large amounts in stool, therefore acquired by fecal/oral route
  2. Often occur in summer or early fall in temperate climates

3. Spread/Multiplication

  1. Virus is ingested, replicates in lymphoid tissue of the pharynx and/or small intestine, and transient viremia causes mild illness
  2. If viremia persists, major viremia develops and can spread to distant organs causing severe disease

4. Damage

4.1. Poliovirus

  1. Replication is accompanied by destruction of infected host cells
  2. Can spread hematogenously from GI tract to CNS where it replicates in grey matter neurons
  3. Anterior horn cell destruction manifests as flaccid paralysis of limb muscles
  4. Bulbar poliomyelitis can cause paralysis of respiratory muscles

4.2. Coxsackie A and B, Echovirus and Enterovirus

  1. Can cause asymptomatic or mild febrile infections, respiratory symptoms, rashes, or aseptic meningitis
  2. 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
  3. Coxsackie B can cause pleurodynia characterized by fever, headache and severe pleuritic pain
    1. Also causes myocarditis and pericarditis 50% of the time

4.3. Key Virulence Factors

  1. Spread from GI tract to distant organs due to presence of specific receptors on the membranes of target cells

4.4. Diagnosis

  1. Epidemiological history is key
  2. Requires isolation from involved site
  3. Serological tests not necessary because enteroviruses do not share common antigens

4.5. Treatment

  1. No therapy for enterovirus infections
  2. gamma-globulini for severe Echovirus or Coxsackievirus infection
  3. Salk or Sabin vaccines for polio

4.6. Outcome

  1. Rarely cause severe disease
  2. Polio has been eradicated in the U.S. since vaccine development