Central nervous system infections in a tropical area: influence of emerging and rare infections

Background and purpose The frequency of infectious encephalitis and the distribution of causative pathogens in tropical areas are poorly known and may be influenced by emerging and rare infections. The aim was to characterize a large series of acute infectious encephalitis and myelitis in immunocompetent patients from the Caribbean island of Guadeloupe identifying clinical, biological and radiological features according to pathogens. Methods Using a hospital database, detailed information on a comprehensive series of immunocompetent patients with acute infectious myelitis and encephalitis over the 2012-2018 period was retrospectively collected. Results From 259 suspected cases with acute central nervous system infection, 171 cases were included for analysis, comprising 141 encephalitis, 22 myelitis and eight encephalomyelitis. The annual incidence peaked at 15.0/100 000 during the Zika 2016 outbreak. Children accounted for 22.2% of cases. Eight adults died during hospital stay, all encephalitis. Seventeen infectious agents, two of which had never been described in Guadeloupe so far, were identified in 101 cases (59.1%), including 35 confirmed cases (34.7%), 48 probable cases (47.5%), 15 possible cases (14.9%) and three clinical cases (3.0%). The most frequent etiologic agents were Zika virus in 23 cases (13.5%), herpes simplex in 12 (7.0%), varicella zoster virus in 11 (6.4%), dengue virus in 11 (6.4%) and leptospirosis in 11 (6.4%). Conclusions The Zika outbreak had a major influence on the annual incidence of acute central nervous system infection. Acute neuroleptospirosis is over-represented in our series. Further efforts are mandatory to develop new diagnostic tools for pathogen profiling.