Polio

The Polio virus is an enterovirus which is found in contaminated water. It resists stomach acids and bile, and infects lymphoid tissues in the oral and intestinal mucosa. By eventually infecting skeletal muscles, it gains access to motor neurons, traveling into the spine and brainstem and eventually killing the host cell. Depending on the number of neurons affected, the illness may be asymptomatic (90%), minor (flu-like), nonparalytic (meningitis) or paralytic.

Summary

• Cause: Polio virus (picornavirus)
• Transmission: fecal-oral (enterovirus)
• Symptoms: Asymptomatic (90%); fever, malaise, vomiting, headache in 5%
• Pathogenesis: Viremia, infection of target cells + immune response lead to early symptoms. If virus spreads to CNS (motor neurons) paralysis can result
• Complications: meningitis (1-2%), paralysis (0.5 - 2%), bulbar polio, post-polio syndrome
• Treatment: pleconaril can prevent picornavirus entry into cells if administered early
• Immunity: lifelong
• Vaccine: IPV and OPV