Doctors have identified the germ that’s sickened many schoolkids in Grinnell. Registered nurse Judy Bush works with Grinnell Regional Public Health. She says it’s been identified as the Norwalk Virus, a major cause of many gastrointestinal illnesses. Almost one-fifth of the students were out sick, and the Grinnell-Newburg Schools declared a three-day weekend last week to let the outbreak subside.She says it’s slowed down now, and the school absenteeism is back to normal levels. Bush reminds those who’ve had the virus to stay home till they’ve been symptom-free for about 48 hours so they can’t spread it further. Though symptoms are intense, the R.N. says it won’t last long. The disease is “self-limiting” in kids and usually lasts only 24 to 48 hours, and the biggest concern is that kids and elderly not get dehydrated while they’re sick. The public health nurse says nobody knows where the bug started but it’s easily spread and hand-washing is important to stopping it.