CLINICAL DESCRIPTION

Infection with poliovirus results in a spectrum of manifestations.  The overwhelming majority of infections (95%) are clinically inapparent.  Some 4-8% of infected individuals will experience non-specific viral symptoms, such as a low-grade fever, headache, sore throat, nausea, abdominal pain, constipation, diarrhea, and/or vomiting (abortive disease).  Some 1-5% of infections will result in aseptic meningitis, involving stiffness of the back, neck and/or legs, at times with paresthesias, a few days after the minor illness has resolved.  Only about 0.1-1% of infections will progress to acute flaccid paralysis (AFP) with loss of reflexes in the involved limbs, usually with fever present (paralytic poliomyelitis).  Please note, today in the US, the most common cause of AFP is Guillain-Barré Syndrome.

Progression to paralytic poliomyelitis usually occurs within 2-4 days and rarely continues after the fever subsides.  Spinal paralysis is typically asymmetric, more severe proximally than distally.  Paralysis may compromise respiration and swallowing.  After the acute episode, many patients recover at least some muscle function and prognosis for recovery can usually be established within 6 months after onset of paralytic disease.  Between 2-10% of paralytic infections are fatal.  Risk factors for paralytic disease include larger inoculum of poliovirus, increasing age, pregnancy, strenuous exercise, tonsillectomy, and intramuscular injections administered while the patient is infected with poliovirus.

Infection with poliovirus  results in life-long, serotype-specific immunity.  Long-term carrier states are rare and have been reported only in immunodeficient persons. 

Some 25-40% of persons who contracted paralytic poliomyelitis in childhood may develop “post-polio syndrome” 30 to 40 years later.  This syndrome is characterized by muscle pain, exacerbation of existing weakness, and/or development of new paralysis or weakness.  Risk factors for developing this syndrome include a) increasing time since acute polio infection, b) the presence of permanent residual impairment after recovery of the acute illness, and c) being female.

The NJDHSS Public Health Environmental Laboratories (PHEL), as necessary for diagnostic purposes, will test stool, throat and CSF specimens for poliovirus.  Stool, throat, and cerebrospinal fluid (CSF) clinical specimens should be collected.  A stool specimen is the most likely source from which to isolate poliovirus, although isolation of virus from stool alone does not constitute proof that poliovirus is the causative agent.  A throat specimen, followed by CSF, is the next likeliest source for virus.  Isolation of poliovirus from CSF is diagnostic, although it is rarely accomplished.  The PHEL can perform techniques to isolate enteroviruses, including poliovirus (serotypes 1, 2, and 3), echovirus, coxsackievirus (A and B), and enteroviruses (70 and 71) from all of these clinical specimens.  If poliovirus is isolated, testing can be performed at the Centers for Disease Control and Prevention (CDC) to determine if it is a vaccine or wild-type strain.

 

CASE CLASSIFICATION

Clinical case definition for paralytic poliomyelitis:

Acute onset of a flaccid paralysis of one or more limbs with decreased or absent tendon reflexes in the affected limbs, without other apparent cause, and without sensory or cognitive loss.

1. CONFIRMED
   
   A case that meets the clinical case definition and in which the patient has a neurologic deficit 60 days after onset of initial symptoms, has died, or has unknown follow-up status.
   

2. PROBABLE

   A case that meets the clinical case definition.
   
   

3. POSSIBLE
   
   Not used