Abstract
The objective of this study was to characterize the prevalence of viral encephalitis due to arbovirus infection of the Togaviridae and Flaviviridae families in São Paulo, Brazil. A total of 500 cerebrospinal fluid (CSF) samples collected between August 2012 and January 2013, from patients with symptoms of acute encephalitis were analyzed. Findings suggestive of viral encephalitis—elevations in cell concentration, glucose and total protein—were observed in 234 (46.8%) samples, designated as Group 1. The remaining 266 samples comprised Group 2. All samples were tested for Flaviviruses (dengue virus 1, 2, 3 and 4, yellow fever virus and West Nile virus), Alphavirus (NS5 region) and enterovirus by RT- PCR and for herpesviruses and enteroviruses using CLART-Entherpex. A presumptive viral etiological agent was detected in 26 samples (5.2%), 18 (8.0%) in Group 1 and 8 (3.0%) in Group 2. In Group 1 human herpesviruses were detected in 9 cases, enteroviruses in 7 cases, dengue viruses (DENV) in 2 CSFs and St. Louis encephalitis virus (SLEV) in one case. In Group 2 there were 3 CSFs positive for human herpesviruses, 2 for enteroviruses, 2 for DENV and 1 for SLEV. Detection of arboviruses, even though present in a minority of infected patients, identifies these viruses as a probable etiological agent of encephalitis. This is of special concern in regions where this class of viruses is endemic and has been linked to other recent epidemics.
Highlights
Encephalitis is associated with high morbidity and mortality, as well as with cognitive, behavioral and even symptomatic epilepsies [1]
These patients, whose cerebrospinal fluid (CSF) findings were suggestive of viral encephalitis, were designated as Group 1
We found only a low prevalence of arboviruses in this encephalitis population, there remains a need to employ molecular tests to identify this class of viruses in patients with encephalitis
Summary
Encephalitis is associated with high morbidity and mortality, as well as with cognitive, behavioral and even symptomatic epilepsies [1]. 60% of patients suffer from severe memory disorder, which presents as clinical dementia [1]. In addition to the personal, family and social cost, if these patients survive, they rarely become productive again [1,2]. The incidence of encephalitis ranges from 1.5 to 8/100,000 inhabitants, being higher in children under one year of age [3,4]. Viruses known to cause encephalitis worldwide are herpesviruses, arboviruses and enteroviruses [1]. Arboviruses are the leading cause of encephalitis worldwide [2]. Herpes simplex virus type 1 (HSV-1) is the leading cause of sporadic encephalitis in adults, while Varicella zoster virus (VZV) is responsible for up to 22% of pediatric cases [1]
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