ICD-10-CM > A00-B99 > A00-A09 > A08 > A08.1 A08.1 Acute gastroenteropathy due to Norwalk agent and other small round viruses Non-Billable/Non-Specific Codes A08.11Acute gastroenteropathy due to Norwalk agentA08.19Acute gastroenteropathy due to other small round viruses