Enterovirial Infections

Enterovirus infections are very common in infants and children. They are RNA viruses that belong to the picornaviridae family and include the coxackieviruses, echoviuses, and polioviruses.  

Epidemiology and Pathogenesis

  • Enteroviruses are often called "summer viruses," because they are more common between May and October
  • Most cases affect children under 5 years old. 
  • Infections are more common in lower socio-economic groups. 
  • Humans are the only hosts, and transmission is usually via the fecal-oral route. Neonates can become infected during birth or via an infected clinician. 
  • The incubation period is 3-6 days. 
  • The virus enters the body via the oral or respiratory route. It then replicates in the lymph nodes of the GI or respiratory system. An initial minor viremia results in spread to additional sites that can include the heart, liver, skin and CNS. 
  • Antibodies to the virus develop, the viremia ends, and the patient improves clinically. 
  • Viral shedding can occur for many weeks after infection. 
  • Of note, different members of a single family may manifest different symptoms from infection with the same virus.

Clinical Manifestations

  • Most patients only develop a mild illness and and recover completely, but some patients have more serious disease. 
  • In general, enteroviruses cause febrile illnesses, which are often accompanied by a viral exanthem, vomiting, diarrhea, and malaise. 
  • There are some more serious manifestations of disease, some of which are known to be caused by specific enterovirus types:  
  • Hand, Foot and Mouth Syndrome: Vesicular lesions develop on the bucchal mucosa and tongue. Small, tender cutaneous lesions also develop on the palms, soles, buttocks (and occasionally genitals). The incubation period is 3-5 days, and the infection usually resolves within 2-3 days without complications. Hand, food and mouth disease is often caused by the Coxsackie A group of viruses, but can be caused by other enteroviruses as well. This illness is moderately contagious, and virus can be shed for weeks after symptoms resolve. Children should be excluded from school during the first few days of the illness, but this will not disrupt transmission entirely. 
  • Herpangina: Herpangina is also caused by coxsackie A. This is characterized by vesicles on the tonsils and soft palate, and frequently occurs in children between 3 and 10 years old. Patients have sore throat, fever, and difficulty swallowing. 
  • Myopericarditis: Enteroviruses often infect the myocardium as well as the epicardium. Commonly caused by coxsackie B, these infections may be without symptoms or fulminant and result in heart failure. 
  • Pleurodynia: Pleurodynia is typified by the abrupt onset of chest and abdominal pain and spasms. Commonly caused by coxsackie A and echoviruses, this is more common in teens and adults. Most people have symptoms for 4-6 days. 
  • Aseptic meningitis: Non-polio enteroviruses are the most commonly identified causes of aseptic meningitis (commonly coxsackie B and echoviruses). Meningitis is characterized by headache, vomiting, photophobia, and stiff neck in older children, but is often diagnosed in infants during the work-up for fever without a source. 
  • Neonatal sepsis: Neonates are at a high risk for developing multi-organ failure from infection with coxsackie B types 2-5 and echovirus 11. Clinically, these infections can be difficult to distinguish from bacterial sepsis. Patients may present with CNS, cardiac, pulmonary, and liver disease. Management is supportive. 
  • Polio: Poliovirus infections have been nearly eliminated worldwide due to vaccination. 

Diagnosis

  • Viral Culture: Virus can be cultured from stool, CSF, throat swabs, blood, and tissue. Highest yields come from stool and throat swabs. 
  • PCR: PCR is commonly used to examine CSF. It is fast and reliable. 
  • Serologies: Serologic tests exist, but due to variations in titers and the large number of enterovirus subtypes, these tests are rarely practical. 

Treatment

  • Supportive care is usually the only required treatment. Enteroviral diseases are typically self-limited, but patients may benefit from antipyretics, pain relief, and fluids.
  • IVIG: May have utility in immunocompromised patients with persistent enteroviral infections.  
  • Pleconaril: Pleconaril is an anti-viral that prevents viral uncoating and attachment to host cells. It has been used in clinical trials for enteroviral meningitis and neonatal infections. More research about its efficacy is required at this time. 

References

  1. Caddle, S. Enteroviruses. Pediatrics in Review. 2003;24:358. 
  2. Pasquenelli, L. Enteroviral Infections. Pediatrics in Review. 2006;27:e14. 
  3. Chang l. et al. Neurodevelopment and Cognition in Children with Enterovirus 71 Infection. NEJM. 2007;356:1226. 
  4. Yun W, et al. Enteroviral Meningitis without Pleocytosis in Children.  Archives of Disease of Children. 2012;0:1-5. 
  5. Zaoutis T and Klein JD. Enterovirus Infections. Pediatrics in Review. 1998;19:183. 

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