Enterovirus-associated encephalitis in the California encephalitis project, 1998-2005.
BACKGROUND
Encephalitis is a relatively rare presentation of enterovirus (EV) infections. Clinical and epidemiologic characteristics of EV encephalitis (EVE) have not been well characterized.


METHODS
Patients with encephalitis enrolled in the California Encephalitis Project from 1998 to 2005 were tested for a range of pathogens, including EV, using a standardized diagnostic algorithm. EVE was categorized as "confirmed" (EV detected in cerebrospinal fluid [CSF] or brain tissue) or "possible" (EV found in respiratory or fecal specimens or serum EV immunoglobulin [Ig] M detected). We compared clinical and epidemiologic characteristics of EVE with those of other infectious encephalitis cases.


RESULTS
EVE was diagnosed in 73 (4.6%) of 1571 patients (45 confirmed cases, 28 possible cases); 11.1% of cases had other infectious causes. Patients with confirmed EVE were younger, although 27% were adults, who presented with significantly less severe symptoms. Serotypes identified in EVE cases correlated with the predominant serotype for the given year reported to the National Enterovirus Surveillance System at the Centers for Disease Control and Prevention. Two of 4 fatal EVE cases were associated with EV71.


CONCLUSIONS
EVs are an important cause of encephalitis cases requiring hospitalization, in both children and adults. Our data suggest that EVE severity varies by serotype, confirm the importance of CSF/brain tissue polymerase chain reaction, and demonstrate that serum IgM findings are of little value in diagnosing EVE.
Fowlkes
Ashley L
AL
Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333, USA. ahl4@cdc.gov
Honarmand
Somayeh
S
Glaser
Carol
C
Yagi
Shigeo
S
Schnurr
David
D
Oberste
M Steven
MS
Anderson
Larry
L
Pallansch
Mark A
MA
Khetsuriani
Nino
N
D000293:Adolescent; D000328:Adult; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D018792:Encephalitis, Viral / Q000453:epidemiology* / Q000821:virology*; D004770:Enterovirus / Q000145:classification / Q000302:isolation & purification; D004769:Enterovirus Infections / Q000453:epidemiology* / Q000821:virology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012621:Seasons; D013997:Time Factors