Journal of Medical Virology 65:340±347 (2001) Circulation of Enteroviruses and Persistence of Meningitis Cases in the Winter of 1999±2000 Martine Chambon,* Christine Archimbaud, Jean-Luc Bailly, Ce  cile Henquell, Christel Regagnon, Franc Ë oise Charbonne Â, and He Âle Á ne Peigue-Lafeuille Laboratoire de Virologie, FaculteÂde MeÂdecine et CHRU,Clermont-Ferrand, France The seasonal incidence of enterovirus meningitis was analyzed in a prospective study of patients admitted for suspected meningitis from October 1, 1998 to April 30, 2000. In-house reverse transcription-polymerase chain reaction (RT- PCR) in cerebrospinal ¯uid (CSF) was used irrespective of cytological results. Fifty-two (45.2%) of the 115 patients had positive RT-PCR in CSF, including 44/86 children (51.2%) and 8/29 adults (27.6%). Six of the 52 (11.5%) had no pleocytosis. The numbers of CSF specimens with a predominance of lymphocytes or a predomi- nance of neutrophils were closely similar. In 33 of the positive patients, an enterovirus, mainly echoviruses type 6 (48%) and 30 (24%), was recovered in one or more specimens. Sixteen cases of enteroviral meningitis were observed between November 1999 and March 2000 as against 2 cases between November 1998 and March 1999, showing that the disease persisted through the winter months of 1999±2000. During the same period, 96 enterovirus isolates were recovered from clinical specimens from other patients. The number of isolates was higher in the winter of 1999±2000 (P < 0.01) than in the winter of 1998±1999, indicating that the risk of enterovirus infection increased sig- ni®cantly in winter 1999±2000. Sixteen patients had aseptic meningitis, made a rapid recovery and had an enterovirus in throat swabs and stools (9/16) or in one of the two (7/16). RT-PCR was not requested. Nine patients were admitted during the cold months. The clinical management of both adult and child patients could be improved by year-round use of enterovirus generic RT-PCR. J. Med. Virol. 65:340 ± 347, 2001. ß 2001 Wiley-Liss, Inc. KEY WORDS: echovirus; coxsackievirus; epidemiology; RT-PCR; cerebrospinal ¯uid; adult INTRODUCTION The enteroviruses form a large, clinically important group of human viruses. The genus Enterovirus comprises 64 serotypes divided into four groups: Human enterovirus (HEV) A, B, C, and D [King et al., 2000]. Nonpolio enteroviruses cause infections of vary- ing severity that increase signi®cantly the yearly number of hospitalizations in pediatric units [Romero, 1999]. They are the commonest identi®ed cause of viral meningitis, particularly in infants and young children, and are not uncommon in the adult population [Modlin, 1997; Andre Âoletti et al., 1998]. Studies of meningitis outbreaks and of general enterovirus circulation have shown repeatedly that in temperate climates of both the northern and southern hemispheres enteroviral infections occur mainly during the summer and the early months of the autumn [Yamashita et al., 1992; McIntyre and Keen, 1993; Ashwell et al., 1996; Nairn and Clements, 1999]. However, all these epidemiological studies focused on a retrospective analysis of the enteroviral strains isolated. Many reports have documented the greater sensitivity of reverse transcription-polymerase chain reaction (RT-PCR) test on cerebrospinal ¯uid (CSF) compared with traditional cell culture methods. The test is able to detect a low viral load in certain CSF specimens, infectious and noninfectious viral particles and enterovirus serotypes that cannot usually be propagated in tissue culture, particularly group A coxsackieviruses [Lina et al., 1996; Muir et al., 1999; review in Romero, 1999]. The use of RT-PCR in routine enteroviral meningitis diagnosis could improve our understanding of the true seasonal incidence of this infection. Grant sponsor: Ministe Áre de l'Education Nationale, de la Recherche et de la Technologie; Grant number: EA2148. *Correspondence to: Martine Chambon, Laboratoire de Virolo- gie du CHRU, Faculte  de Me  decine, 28 place Henri Dunant, 63001 Clermont-Ferrand Cedex 1, France. E-mail: martine.chambon@u-clermont1.fr Accepted 9 March 2001 ß 2001 WILEY-LISS, INC.