eMedicine Specialties > Infectious Diseases > Viral Infections

Echoviruses: Differential Diagnoses & Workup

Author: Larry I Lutwick, MD, Professor of Medicine, State University of New York, Downstate Medical School; Director, Infectious Diseases, Veterans Affairs New York Harbor Health Care System, Brooklyn Campus
Coauthor(s): Syed Hussain, Department of Surgery, Nassau University Medical Center
Contributor Information and Disclosures

Updated: Jun 29, 2006

Differential Diagnoses

Coxsackieviruses
Enteroviruses

Other Problems to Be Considered

Poliovirus infections

Workup

Laboratory Studies

• Viral isolation through cell culture
  • The opportunity to recover a virus in cell culture is optimized by sampling multiple sites.
  • Late in the course of echoviral illness, clinicians use viral cultures of feces because the lower intestine may be the only site from which the agent is still excreted. Physicians can confirm an etiologic diagnosis by isolating virus from CSF, pericardial fluid, tissue, or blood, depending on the clinical syndrome. Remember that the isolation of an echovirus from the stool does not necessarily signify that a systemic or focal illness is due to that virus because it may be an innocent bystander unrelated to pathology elsewhere.
  • With the identification of a characteristic cytopathic effect in any 3 or 4 appropriately chosen cell lines, the laboratory can report a presumptive diagnosis of echoviral infection within several days.
  • In the future, echoviral strains likely will be characterized by genomic sequencing.
• Polymerase chain reaction
  • Reverse transcriptase–polymerase chain reaction (RT-PCR) is a rapid, sensitive, and specific method of detecting echoviral RNA in clinical specimens.
  • RT-PCR has detected echoviral RNA from CSF, throat swabs, serum, and stool samples. It also has detected echoviral RNA in endomyocardial biopsy specimens from cases of acute myocarditis and is the standard method for the diagnosis of enteroviral meningitis.
• Serology
  • The optimal use of antibodies for the diagnosis of echoviral infections involves acute and convalescent sera, which should be run in parallel, if possible. A single high antibody result can be misleading.
  • The microneutralization test is the most widely employed method for the determination of antibodies to echoviruses.
• CSF analysis
  • In chronic meningoencephalitis in hosts who are agammaglobulinemic and other hosts who are immunocompromised, the CSF exhibits lymphocytic pleocytosis and a higher protein concentration than usually is observed in cases of acute enteroviral aseptic meningitis. Enteroviruses can be recovered repeatedly from the CSF over a period of months to years, usually in high titer.
  • In some cases, the virus is isolated only intermittently from CSF or detected only by polymerase chain reaction (PCR). For unknown reasons, finding the virus in the feces usually is more difficult than finding the virus in the CSF. Clinicians have recovered enteroviruses from many other sites in these patients, including the brain, lung, liver, spleen, kidney, myocardium, pericardial fluid, skeletal muscle, and bone marrow. Some patients have been infected with more than one enterovirus serotype, either concurrently or sequentially.

Imaging Studies

• Radiography: In myopericarditis, enlargement of the cardiac silhouette on chest radiograph films is present in approximately 50% of cases and may be due to either pericardial effusion or cardiac dilatation.
• Echocardiography: Echocardiography may confirm the presence of acute ventricular dilatation or a diminished cardiac ejection fraction.

Other Tests

• Electrocardiography: Patients invariably have electrocardiographic abnormalities. With pericarditis or mild myocarditis, these abnormalities consist of ST-segment elevation or nonspecific ST-segment and T-wave abnormalities. More severe myocardial disease may lead to the development of Q waves, ventricular tachyarrhythmias, and all degrees of heart block.

Histologic Findings

In enteroviral myopericarditis, viruses reach the heart during the viremia that follows replication in the GI or respiratory tract. Experimental studies in a murine model strongly suggest that virus replication occurs in the myocytes. A chronic inflammatory response persists for weeks to months when the replicating virus is no longer present in the heart, and this lingering response is the subject of keen interest. Some investigators consider the late-phase inflammatory response to be due to virus-induced, cytotoxic T-lymphocyte destruction of myocytes. Others postulate the development of a myocardial neoantigen or cross-reactivity between viral and myocardial cell antigens. A variable degree of interstitial fibrosis and evidence of myocyte loss accompany healing.

• Search for CME/CE on This Topic »

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