Preferred Test for Coxsackie Virus Infection
The preferred test for diagnosing Coxsackie virus infection is nucleic acid amplification testing (NAAT/RT-PCR) performed on multiple specimen types collected simultaneously, including respiratory specimens (nasopharyngeal swab or throat swab), stool samples, and cerebrospinal fluid when CNS involvement is suspected. 1
Primary Diagnostic Approach
Specimen Collection Strategy
Collect multiple specimens from different anatomical sites simultaneously as soon as possible after symptom onset to maximize diagnostic yield, as Coxsackie viruses (part of the enterovirus family) may be detected in different body sites depending on clinical presentation and timing. 1
The specific specimens to collect depend on clinical presentation:
- For meningitis/encephalitis: CSF, stool, AND respiratory sample (throat or nasopharyngeal swab), with blood sample also considered 1
- For myocarditis/pericarditis: Pericardial fluid or tissue biopsy if available, plus stool and respiratory samples 1
- For hand-foot-mouth disease: Vesicle fluid (highest viral load), respiratory sample, and/or stool 1, 2
- For neonatal sepsis: CSF, stool, blood, AND respiratory sample 1
Testing Methodology
RT-PCR targeting the 5' non-coding region (5'NCR) is the gold standard diagnostic method with superior sensitivity (>95%), specificity, and rapid turnaround time compared to viral culture. 1, 3, 4
Key performance characteristics:
- RT-PCR sensitivity for enterovirus CNS infection: >95% 1
- Viral culture sensitivity: only 65-75% 1
- RT-PCR can detect virus in CSF within 5 hours versus 3-7 days for culture 5
- RT-PCR shows two orders of magnitude greater sensitivity than cell culture 4
Methods to Avoid
Do not rely on serology for acute Coxsackie virus diagnosis except in the specific context of determining past exposure to Coxsackie B virus in patients with myocarditis, where acute and convalescent titers are required due to high seroprevalence in the population. 1, 3
Do not use viral culture as the primary diagnostic method - it is time-consuming, less sensitive than RT-PCR, and many Coxsackie A strains are difficult to grow in standard cell culture, historically requiring newborn mouse inoculation. 1, 6
Critical Interpretation Caveats
Detection of enterovirus RNA in throat or stool specimens must be interpreted cautiously because viral shedding can persist for weeks to months after acute infection, so detection does not automatically prove causation of current symptoms. 1, 3
For CNS infections, always test CSF even though it may be negative - certain enterovirus types (particularly EV-D68 and EV-A71) are often only detectable in respiratory specimens or stool, not CSF. 1, 3
In neonates with sepsis syndrome, plasma or serum testing is useful, but this is less reliable beyond the newborn period. 1
Specimen Handling Requirements
- CSF: Sterile container, room temperature, transport immediately (do not refrigerate) 1
- Respiratory specimens: Nasopharyngeal swab or aspirate, room temperature, ≤2 hours 1
- Stool: Fresh specimen preferred for optimal yield 1
- Blood (if needed): Collect before any immunoglobulin administration 3
Common Pitfalls to Avoid
Do not test only CSF in suspected CNS infections - respiratory and stool specimens significantly increase diagnostic yield, particularly for EV-D68 and EV-A71 associated with acute flaccid myelitis. 1, 3
Do not assume negative RT-PCR rules out enterovirus infection if only one specimen type was tested - multiple specimen types collected simultaneously provide the highest sensitivity. 1, 3
Do not order bacterial antigen testing on CSF as a substitute for molecular testing - this is not recommended for enteroviral meningitis diagnosis. 1
In immunocompromised patients, maintain a low threshold for testing as viral shedding can persist for years and clinical presentations may be atypical. 3