Clinical manifestations of Japanese encephalitis in southern Taiwan

Background and purpose: Japanese encephalitis virus infection is a sporadic infectious disease in Taiwan. Despite progress in laboratory examinations and imaging studies, diagnosis of Japanese encephalitis remains underestimated. This study was conducted to identify clinical symptoms and laboratory findings that may assist in early identification of this disease. Methods: This retrospective study included all patients diagnosed with Japanese encephalitis at Kaohsiung Veterans General Hospital from January 2000 through December 2007. Epidemiologic data, predisposing factors, neurological and non-neurological signs and symptoms, laboratory data, and treatment were analyzed. Outcomes and neurological complications were evaluated. Results: Eleven patients had Japanese encephalitis, and 10 had sufficient information for enrolment into the study. Nine patients presented with non-significant constitutional symptoms of fever, nausea, or headache. Other signs and symptoms included rhinorrhea, sore throat, abdominal pain, cough, myalgia, or arthralgia. Eight patients had lymphocytic pleocytosis with elevated protein and borderline low glucose levels in the cerebrospinal fluid. Leptomaningeal enhancement and low density lesions were the most common computed tomography findings. T2 hyperintensity lesions and leptomeningeal enhancement were seen in 5 patients. Two patients presenting with acute flaccid paralysis had high intensity lesions on the thalamus and basal ganglion. There were no correlations between clinical, laboratory and imaging findings. None of the patients had neurological sequelae. Conclusions: Presentations, laboratory examination, and clinical signs are not specific for Japanese encephalitis. Sporadic cases are usually seen from May to August, which are associated with monsoon rains. Hence increased awareness of this disease is recommended during these periods.