Assertion: polio's infection | /r/Causes | symptom
Facets:
value: in many cases
type: TEMPORAL
value: in a small minority
type: LOCATION
Source sentences:
text: Throughout most of human history the polio virus was ubiquitous and infected almost all children as soon as they were weaned from breast milk to a mixed diet, but infection caused symptoms in only a small minority.
text: Poliomyelitis occurs when the virus invades the nervous system and attacks nerves that activate muscle movement, but in many cases infection with the polio virus causes no signs or symptoms at all.