External quality assessment of enterovirus detection and typing. European Union Concerted Action on Virus Meningitis and Encephalitis.

Reported are the results of a study of an enterovirus proficiency panel for use in isolation and serotyping and/or the polymerase chain reaction (PCR) carried out by 12 laboratories in nine European countries. Eleven laboratories reported results of virus isolation and serotyping. In addition, four laboratories reported results of a PCR for enterovirus detection. Correct virus isolation results were obtained for 105 of 110 samples (95.5%, four false-negatives, one false-positive), and correct PCR results for 39 of 40 (97.5%, one false-negative). The highest isolation rate (87.5%) was observed in primary and tertiary monkey kidney cells; on monkey kidney cell lines, human diploid fibroblasts or human heteroploid cells the isolation rate varied between 64% and 71.4%. Serotyping results were less satisfactory. Only 63 of 106 (59.4%) isolated viruses were typed correctly. Major problems were seen with samples containing mixtures of enteroviruses and with enterovirus 71 or echovirus 4, with 9%, 50%, and 55% correct results, respectively. These results underline the need for improvement of enterovirus typing, especially in view of the poliomyelitis eradication initiative.