Two samples of feces weighing at least 8 grams should be taken from each patient separated by at least 24 hours, up to 14 days from the onset of symptoms. Stool samples should be frozen at this temperature. – 20 ºC and immediately send to the National Center for the Diagnosis of Infections with Polioviruses (National Poilivirus Laboratory – NPL) located in the Department of Virology NIZP-PZH. The sample testing process including possible virus isolation should be completed within 28 days. Virological tests are carried out according to the recommended by the WHO procedures, including, inter alia, insulation in 2 RD and L20 B cell lines, and the preparation of chloroform samples. Isolated poliovirus strains are sent to the Reference Laboratory in Berlin, where their origin is determined and whether it is a wild or vaccine strain. Currently, after documenting that the European region is free of poliovirus, stool samples are not routinely collected from people in contact with ophid patients. It is recommended to take stool samples from contact persons if a child with severe flaccid paralysis has not been vaccinated against poliomyelitis, or has come from an area where wild virus strains still occur.