Enteroviruses Workup

Updated: Mar 01, 2018
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Michael Stuart Bronze, MD  more...
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Workup

Laboratory Studies

Diagnosis of enterovirus infections is often clinical. Laboratory diagnosis can be achieved with serological tests, viral isolation by cell culture, and polymerase chain reaction (PCR).

Serology

The microneutralization test is the most widely used method for detecting antibodies to enteroviruses. Serological examination reveals a 4-fold increase in antibodies to enteroviruses between the acute and convalescent phases of illness. [56] This diagnostic modality is infrequently used since it is serotype-specific, relatively insensitive, poorly standardized, labor intensive, and too slow for clinical purposes.

Viral isolation

The virus can be isolated from CSF, blood, or feces, depending on the site affected, and the yield is increased if multiple sites are sampled. Enterovirus produces a characteristic cytopathic effect in cultured cells. Poliovirus is easily cultured from stool and nasopharyngeal secretions, but isolation from the CSF is more difficult. The cytopathic effect is confirmed by indirect immunofluorescence using a broadly specific monoclonal antibody. The sensitivity of viral culture ranges from 60%-75%. [57]

Polymerase chain reaction

This rapid test is highly sensitive and specific for detecting enteroviral RNA in CSF specimens, with a sensitivity of 100% and specificity of 97%. [58, 59] PCR provides rapid results and is the best diagnostic test for use in CSF but is limited by availability in some areas and cost in underdeveloped regions. [60]

In 2008, a multiplex real-time PCR (RT-PCR) assay was developed for simultaneous detection, identification, and quantification of enterovirus 70 and a coxsackievirus A24 variant. The novel technique is used as a rapid diagnostic method to evaluate for enterovirus-related AHC. [61]

Cardiac enzyme levels

Cardiac enzyme levels may be elevated in persons with myopericarditis, indicating myocardial damage.

CSF analysis

The CSF profile in patients with aseptic meningitis usually reveals a mildly elevated white blood cell count, and the differential invariably shifts to a predominance of lymphocytes during the initial 1-2 days of illness. Glucose levels are normal or mildly decreased, [62] while the protein level is normal or slightly increased.

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Imaging Studies

Chest radiography: In patients with myopericarditis, chest radiography may reveal cardiomegaly secondary to pericardial effusion or cardiac dilation. In pleurodynia, chest radiographic findings are normal.

Echocardiography: Transient wall motion abnormalities may be detectable in mild cases. Severe cases may demonstrate acute ventricular dilation and reduced ejection fraction.

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Other Tests

ECG: Nonspecific ST-T changes may be observed in persons with myopericarditis. Severe disease may cause Q waves, ventricular tachyarrhythmias, and heart block. ECG findings may demonstrate evolution through several stages of myopericarditis, as follows:

  • Stage I - Diffuse ST elevation with PR depression

  • Stage II - Normalization of ST and PR segments

  • Stage III - Deep symmetric inversion of T waves

  • Stage IV - May revert to normal or permanent T-wave inversions

Electroencephalography: This test may be useful for evaluating the extent and severity of illness in patients with encephalitis.

Ophthalmic slit-lamp examination: In persons with AHC, corneal erosions may be visualized using a fluorescein stain. Enterovirus 70 and coxsackievirus A24 can often be recovered from conjunctival swabs during the first 3 days of infection.

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Histologic Findings

Histopathologic findings in most enterovirus infections are usually nonspecific, consisting primarily of lymphocytic infiltrates and cellular destruction.

Histologic findings in patients with polio have been well studied. Evidence of infection is pronounced in the spinal cord, medulla, pons, and mid brain. Neuronal destruction is observed, along with an inflammatory infiltrate composed of lymphocytes, macrophages, and polymorphonuclear leukocytes.

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