Clinical laboratory tests for acute enterovirus infection.
This text is adapted from the website of Enterovirus Foundation.
Diagnosis of Enterovirus Infections is not that simple. Since it can masquerade as many common conditions during early onset, diagnosis often occurs when the virus has progressed to a severe or deadly state. The prolonged nature of an infection or an aforementioned complications arise with the initial infection should lead to further investigation.
Although many hospitals and some doctor’s offices can test ill patients to see if they have an enterovirus infection, most cannot do specific testing to determine the type of enterovirus. Specific lab tests on specimens from a person’s nose and throat, or special tests on blood or spinal fluid and MRI findings have been used to diagnose conditions linked to enterovirus.
After the acute phase of an infection, enteroviruses can disappear from the blood and cerebrospinal fluid completely, but can remain in organs and other tissues. This makes it difficult to diagnose enterovirus infections without a biopsy, and even then, the tests are limited.
Serology – Serological examination can reveal an increase in antibodies to enteroviruses neutralizing antibody level to enteroviruses between the acute and convalescent phases of illness. This diagnostic modality can only identify coxsackie B1-6 and Echo 6, 7, 9, 11, and 30. The other known enteroviruses cannot be identified with this test. A negative serological test does not necessarily mean the absence of enterovirus.
Viral isolation – This is the criterion standard for diagnosing enterovirus infections. The virus can be isolated from cerebrospinal fluid, blood, or feces, depending on the site affected, and the yield is increased if multiple sites are sampled. The serotype of enteroviruses isolated by this method can be identified with neutralizing assays using type-specific antisera by the CDC or by VP1 gene sequencing.
Reverse transcription-Polymerase Chain Reaction (RT-PCR) – This test is highly sensitive and specific for detecting enterovirus RNA in cerebral spinal fluid specimens, with a sensitivity of 100% reported by some studies and specificity of 97%. This test of a nasopharyngeal swab taken from patients with colds helped identify the viruses in EV D68 outbreak. PCR provides rapid results. PCR testing of the blood can only identify the virus in 30% of chronic fatigue syndrome/myalgia encephalomyelitis patients.
Cardiac enzyme levels and troponin 1 – These levels may be elevated in persons with myopericarditis, indicating myocardial damage like inflammation or damage to the heart muscle.
Cerebrospinal fluid analysis – The cerebrospinal fluid profile of patients with aseptic meningitis reveals a mildly elevated white blood cell count. Glucose levels are normal or mildly decreased, while the protein level is normal or slightly increased.