Abortive polio is a minor illness. It accounts for 80-90% of clinically apparent cases of polio infection, chiefly in young children. It does not involve the CNS. The usual symptoms are slight fever, malaise, headache, sore throat and vomiting which hit 3-5 days after exposure to the polio virus. Full recovery occurs in 24-72 hours. There are no permanent disabilities of any kind.

Polio as a major illness is in contrast to abortive polio. Symptoms appear usually with no sign of a prior illness 7-14 days after exposure to the virus, particularly in older children and adults, and may include fever, severe headache, stiff neck and back, deep muscle pain, and sometimes areas of hyperesthesia (increased sensation) and paresthesia (altered sensation). There may be no further progression from this picture of viral meningitis (called "aseptic" meningitis) or there be loss of tendon reflexes and weakness or paralysis of muscle groups.

Polio can thus take one of two main avenues: that of minor ("abortive") illness or that of major illness. And polio as a major illness can then take one of two branching roads: that of aseptic meningitis without paralysis or that of paralytic polio.

In abortive polio, recovery is complete. Recovery is also complete in polio with only aseptic meningitis. In paralytic polio, about 50% of patients recover with no residual paralysis, about 25% are left with mild disabilities, and the remaining patients have severe permanent disability.

The word "abortive" here means "tending to cut short" so that abortive polio is polio cut short.