But it also meant that the other half started showing symptoms earlier.
Most people show symptoms within 48 hours of exposure to the virus.
"They haven't been here very long, but some of them are already starting to show symptoms."
His temperature was normal and he didn't show symptoms a anything else.
Two more students in the school district began showing similar symptoms making three probable cases.
The virus has to travel to the brain before you show symptoms.
But 5 to 10 percent of patients start showing symptoms when they are younger than 20.
Eventually 600 out of the 3,600 girls at the school showed symptoms.
Other times, it may take a few days for brain swelling to show symptoms.
Most people who develop it show symptoms by age 30.