Is There a Test for Hand, Foot, and Mouth Disease?
Yes, laboratory testing is available for hand, foot, and mouth disease (HFMD), but diagnosis is typically clinical and testing is reserved for specific situations such as severe cases, outbreak investigations, or when complications arise.
When to Test
HFMD is usually diagnosed clinically based on the characteristic presentation of fever, oral lesions, and rash on hands and feet. However, laboratory confirmation becomes important in:
- Severe or complicated cases (neurological involvement, myocarditis)
- Outbreak investigations
- Atypical presentations
- Surveillance purposes
- Cases requiring specific viral typing (EV-A71 vs CV-A16)
Recommended Testing Methods
The gold standard for laboratory diagnosis is reverse transcriptase PCR (RT-PCR) targeting the 5' non-coding region (5'NCR) of enteroviruses due to superior sensitivity, specificity, and rapid turnaround time 1.
Optimal Specimen Types for HFMD
According to European guidelines, the recommended specimens for HFMD testing in order of diagnostic yield are 1:
- Vesicle fluid (primary specimen - highest viral loads)
- Stool samples (high sensitivity - 88% in research studies) 2
- Respiratory samples (throat swabs or nasopharyngeal swabs)
- Rectal swabs (if stool unavailable, similar diagnostic yield) 2
Using multiple specimen types simultaneously increases detection sensitivity 1, 2.
Important Testing Considerations
Specimen-Specific Details
- Vesicle fluid: Contains the highest viral loads and is ideal when vesicular lesions are present 1
- Stool: Research demonstrates 88% sensitivity with 91% agreement with serological reference standards 2
- Throat swabs: Useful but lower yield than stool or vesicle fluid
- Blood/CSF: Generally low yield for typical HFMD; reserved for severe cases with neurological complications
Critical Pitfall
Enteroviruses colonize the throat and gut for weeks to months after infection, so detection in these sites must be interpreted cautiously and correlated with clinical presentation 1. A positive test doesn't automatically prove causation if symptoms are atypical or timing is inconsistent.
Viral Typing
If specific viral identification is needed (distinguishing EV-A71 from CV-A16, which has prognostic implications):
- VP1 capsid protein gene sequencing is recommended for accurate typing 1
- Typing cannot rely on 5'NCR sequences due to frequent recombination events 1
- EV-A71 is associated with more severe complications including rhomboencephalitis, while CV-A16 typically causes milder disease 1
Newer Diagnostic Technologies
Advanced multiplex RT-PCR assays can detect and differentiate multiple enterovirus types simultaneously with high sensitivity (93.8%) and specificity (87.5%), with results available within 1.5 hours 3, 4. These are particularly useful for:
- Early detection in severe cases with low viral loads
- Distinguishing CV-A16 from other coxsackieviruses
- Outbreak surveillance
Practical Clinical Approach
For typical uncomplicated HFMD in children: clinical diagnosis without laboratory testing is appropriate and cost-effective 5. The disease is self-limiting and testing doesn't change management.
Consider laboratory testing when:
- Severe disease or complications develop
- Neurological symptoms appear (meningitis, encephalitis, acute flaccid paralysis)
- Patient is immunocompromised
- Outbreak investigation is needed
- Atypical presentation requires confirmation
The entire diagnostic process from specimen collection to result reporting can be completed within 1.5 hours using modern RT-PCR methods 3, making it feasible for urgent clinical decision-making when needed.