What are the diagnostic criteria and management for poliomyelitis (polio)?

Diagnosis and Management of Poliomyelitis (Polio)

The diagnosis of poliomyelitis requires laboratory confirmation through virus isolation from stool specimens, throat swabs, and serological testing, with stool culture providing the highest yield for poliovirus detection. 1

Clinical Case Definition

Polio should be suspected in cases of:

• Acute flaccid paralysis
• Neurologic deficit present 60 days after symptom onset (unless death occurs or follow-up status is unknown)
• Clinical and epidemiological compatibility with polio 1

Special attention should be given to unvaccinated individuals, particularly those belonging to religious groups that object to vaccination, as the most recent US outbreaks occurred in such communities (Christian Scientists in 1972 and Amish community in 1979). 1

Diagnostic Algorithm

1. Specimen Collection

• Stool specimens: Collect at least two specimens at least 24 hours apart within 14 days of symptom onset (highest yield)
• Throat swabs: Collect at least two specimens at least 24 hours apart (lower yield than stool)
• Serum: Collect acute-phase sample early in illness and convalescent-phase sample at least 3 weeks later
• CSF: May be collected but virus is rarely detected 1

2. Laboratory Testing

The following tests should be performed on collected specimens:

1. Virus isolation in tissue culture (primary diagnostic method)
2. Serotyping of poliovirus isolate as serotype 1,2, or 3
3. Intratypic differentiation using DNA/RNA probe hybridization or PCR to determine if the isolate is vaccine-related or wild virus 1
4. Serological testing: A fourfold rise in neutralizing antibody titer between acute and convalescent serum specimens is diagnostic for poliovirus infection 1
5. IgM antibody detection: Poliovirus type-specific IgM antibody-capture ELISA allows rapid diagnosis within 24 hours of specimen collection 2

Important: Stool specimens collected more than 2 months after onset of paralytic manifestations are unlikely to yield poliovirus. 1

Case Classification

Cases are classified as:

1. Vaccine-associated or wild virus exposure based on laboratory and epidemiologic criteria
2. Occurring in vaccine recipient or contact of recipient based on OPV exposure data 1

Management Approach

Immediate Actions

1. Report suspected cases immediately to local or state health departments 1
2. Initiate epidemiologic investigation with appropriate specimen collection 1
3. Determine if case is likely vaccine-associated or wild virus for appropriate control measures 1

Control Measures

• For wild poliovirus: Conduct active search for misdiagnosed cases (e.g., Guillain-Barré syndrome, polyneuritis, transverse myelitis) and institute immediate control measures including vaccination campaigns 1
• For vaccine-related poliovirus: No vaccination plan needed as no outbreaks associated with live, attenuated vaccine-related poliovirus strains have been documented 1

Surveillance

• CDC conducts national surveillance in collaboration with state and local health departments
• Three independent experts review data to determine if suspected cases meet the clinical case definition 1
• Environmental surveillance through wastewater analysis can detect silent transmission in high-risk communities 3

Common Pitfalls and Caveats

1. Delayed specimen collection: Stool specimens must be collected within 14 days of onset for optimal virus detection 1
2. Reliance on inappropriate serological tests: Neutralization tests are preferred; complement fixation and other tests lack standardization and sensitivity 1
3. Underestimating initial involvement: Historical records show that limbs initially thought to be uninvolved often had clear evidence of initial paralysis that improved 4
4. Missing silent infections: Most poliovirus infections are asymptomatic, requiring sophisticated environmental surveillance to ensure eradication 5

For consultation and specialized testing, the CDC Enterovirus Laboratory is available at (404) 639-2749 for patients with suspected polio. 1