An outbreak of aseptic meningitis in Hatay Province, Turkey.

A meningitis is an inflammation of the meninges with sterile bacterial cultures of CSF.1 Enteroviruses are the most commonly identified cause of aseptic meningitis worldwide. These viruses appear throughout the year, but in temperate climates they are strikingly more prevalent in the summer and fall. Because viral shedding from the gastrointestinal tract is more prolonged than is shedding from the upper respiratory tract, the fecal-oral route is the predominant mode of enteroviral transmission.2 The most severe clinical syndrome caused by enteroviruses is due to infection of the CNS with signs of aseptic meningitis or, less frequently, encephalitis. Although the outcome of enteroviral meningitis is usually favorable in otherwise, healthy and immunocompetent patients, rapid diagnosis and differentiation from bacterial meningitis is imperative because the latter may cause severe neurologic sequelae or even fatal outcome and therefore necessitates immediate antibiotic treatment.3 In this study, we report an unusual community outbreak of aseptic meningitis with a total of 688 patients involved, in the southern region of Turkey, in summer 2005. To determine the possible viral cause of this outbreak, as our hospital is the only reference hospital in the province the specialists and general practitioners dealing with such infections were recommended to transfer the CSF samples of the patients to our clinic for proper storage before their transfer of samples to the Virology Department of Refik Saydam Central Institute of Hygiene (RSCIH) in Ankara. For recording the clinical and laboratory findings with CSF examination results and demographic data of the patients a record form was prepared. Data of the rest of the patients whose CSF samples could not be transferred to our clinic were accessed through medical records of the centers dealing with these patients in the region. The collected CSF samples were transferred at +4°C however, storage conditions before their transfer to our center were not clear. All samples were collected in the acute phase of the disease. The CSF samples of patients were stored at -70°C before transport to the Virology Department of RSCIH in Ankara for viral cultivation. Diagnosis of aseptic meningitis was based on the clinical symptoms indicative of meningitis accompanied by a leukocyte count in the CSF of ≥3/mm3 in the absence of bacterial growth in culture, or any alternative nonviral causes and/ or detection of the viral agent in the CSF. Cell counts of CSF and peripheral blood, CSF analyses for protein and glucose, bacterial cultures, and serum analyses of glucose were performed. Isolation of echovirus was performed by conventional cell culture and micro neutralization methods according to standard procedures as described previously.4 An outbreak of aseptic meningitis in 688 patients occurred in the southern area of Turkey, Hatay between 1 May, and 30 September 2005. Although 688 patients were diagnosed as aseptic meningitis by examination of CSF in the region within this period, only CSF samples of 100 patients could be collected in our center. The highest incidence was in August, 2005, when 354 cases occurred, which accounted for 51.5% of all patients (Figure 1). The patients’ age ranged between 3 months and 46 years with a mean of 8.70 ± 6.88 years. Most of the patients (87.8%) in this outbreak were under 16 years of age. Four hundred and twenty-one (61.2%) patients were male and 267 (38.2%) were female (male: female ratio of 1.58:1). All patients were hospitalized, and the mean hospitalization duration was 5.26 (±2.61) days and minimum one, maximum 21 days. All were discharged without sequelae. During the same period of 2004, only 79 aseptic meningitis cases occurred and most of the cases were in May. The most common clinical manifestations were fever (100%), headache (96%, in older than 4 years old), nausea or vomiting (85%), and neck stiffness (77%, in older than 4 years old). There was a wide variation in the white blood cell (WBC) counts, ranging from 10-1680 cells/mm3 (mean: 192.8±296.4 cells/mm3) and most CSF WBC counts (61%) were less than 100 cells/mm3. The CSF WBC counts between 100-500 cells/mm3 were found in 29% cases, and were over 500 cells/mm3 in 10%. Lymphocyte cell predominance was observed in 91% cases. The mean CSF value of protein was 42.1 mg/dl (range, 20-58 mg/dl), and hypoglycorrhachia (CSF/serum glucose ratio <2/3) was observed in 12% cases. All of 100 CSF samples collected in our center Brief Communication