Lack of Cerebrospinal Fluid Pleocytosis in Young Infants With Enterovirus Infections of the Central Nervous System

OBJECTIVES: To identify factors associated with cerebrospinal fluid (CSF) pleocytosis among infants aged 90 days or younger with enterovirus (EV) infections of the central nervous system (CNS). METHODS: This is a retrospective cohort study performed at an urban academic children's hospital. Patients aged 90 days or younger with a positive CSF EV polymerase chain reaction (PCR) test result obtained during the EV seasons from 2000 to 2006 were included. Patients with concomitant serious bacterial illness or herpes simplex virus infection were excluded. Multivariable logistic regression was used to identify factors independently associated with CSF pleocytosis. RESULTS: A total of 159 patients had a positive CSF EV PCR test result during the study period; 5 (3.1%) were excluded for concurrent serious bacterial infection. The median CSF white blood cell (WBC) count was 110/microL (interquartile range, 11-311/microL). Cerebrospinal fluid pleocytosis was present in 109 patients (71%). The proportion of infants with CSF pleocytosis accompanying EV CNS infections increased with age; CSF pleocytosis was present in 59%, 74%, and 90% of infants aged 0 to 28, 29 to 56, and 57 to 90 days, respectively (P = 0.007). Age and peripheral WBC count were independently associated with CSF pleocytosis. CONCLUSIONS: Among infants with EV CNS infections, the absence of CSF pleocytosis is related to younger age and lower peripheral WBC counts, perhaps reflecting the decreased ability of younger infants to mount a robust inflammatory response to EV infection. Thus, CSF EV PCR testing may be warranted in select patients without CSF pleocytosis.