Use of an enhanced surveillance system for encephalitis and aseptic meningitis for the detection of neurologic manifestations of dengue in Puerto Rico, 2003.

Dengue infection has been implicated as a cause of neurologic manifestations since the beginning of the 20th century. An enhanced surveillance system for encephalitis and aseptic meningitis developed by the Puerto Rico Department of Health in collaboration with the Dengue Branch, Centers for Disease Control and Prevention, identified eleven laboratory positive dengue patients presenting with neurologic manifestations in 2003. Anti-dengue IgM antibody was detected in serum of eight patients and in cerebrospinal fluid of one patient. DENV-2 and DENV-3 were isolated from the serum of one patient each. All patients were negative for serologic markers of West Nile Virus and St. Louis encephalitis. Nine (82%) of the 11 patients had symptoms compatible with encephalitis. Their median age was 46 years (range: 9 months - 82 years) and five were males. Symptoms included severe headache, seizures, altered mental status, confusion, and coma. A motor disorder (upper extremities weakness and Guillain Barré Syndrome, respectively) occurred in two additional patients. Most patients recovered but there were two fatalities. Neurologic manifestations of dengue were rarely reported in Puerto Rico until the institution of enhanced surveillance, which resulted in the recognition of severe and fatal cases.