Polio appears at first to be a minor illness with fever, sore throat, muscle aches, drowsiness, headache, loss of appetite, nausea, vomiting, abdominal pain, and constipation. These symptoms, which may be mistaken for the flu, are followed by viral or aseptic meningitis with a stiff neck, severe headache, vomiting, and lethargy. Polio can cause death. CRS causes multiple malformations, organ abnormalities, and disabilities in the developing fetus, sometimes so severe that death occurs in early infancy. CRS may cause miscarriage.
Spasms can be so strong as to cause bone fractures.
Difficulty swallowing is common and leads to weight loss. If airway blockage occurs, it can result in death. The prolonged course of the disease, which may be as long as 4 weeks, can lead to pneumonia and skin ulcers. Often, lasting impairments in speech, memory, and mental function occur. Ineffective immunization results when an individual's immune system does not respond appropriately.