[An abortive type of tick-borne meningoencephalitis].

OBJECTIVE

Tick-borne encephalitis (TBE) was detected in the Koprivnica-Krizevci County 50 years ago. To date, it has retained the leading position among inflammatory diseases of the central nervous system (CNS), with an average morbidity of 20 patients per year. In 88% of patients, the infection manifested with signs of meningitis or biphasic meningoencephalitis (ME). Monophasic course was recorded in only 12% of patients of older age, during which the first initial stage remained inapparent, and the disease manifested only with ME stage. An abortive type of TBE virus infection with fever, headache and other general symptoms of infection is presented. The initial stage of the disease, without subsequent CNS involvement, is rarely described.

PURPOSE OF WORK

To determine the frequency and present epidemiological, clinical and laboratory characteristics as well as diagnostic procedures in patients suffering from abortive type of TBE.

PATIENTS AND METHODS

A prospective study was conducted in the period from 1997-2002, and included patients with possible tick-borne disease, examined at the Infectious Disease Department of the Koprivnica General Hospital. According to the set criteria, the study included patients of all age groups, sex and occupation, patients with febrile disease (T 38 degrees C) that developed within 6 weeks from the tick bite, patients who showed no signs of ME on their first examination, and patients in whom serologic analysis revealed recent infection with TBE virus. On admission to the hospital, detailed epidemiological and history data were collected, and clinical examination and laboratory testing were performed. ELISA test was used to detect specific IgM and IgG antibodies. At the same time all serum samples were tested for other tick-borne diseases, including Lyme disease and human monocyte and granulocyte ehrlichiosis. Oral consent was obtained from all patients enrolled in the study.

RESULTS

A total of 127 patients met the study criteria. Specific antibodies to TBE virus were detected in 49 (38.5%) patients. After the latency period, 43 (87.7%) patients developed the second stage of ME disease. An abortive type of infection with TBE virus, without subsequent CNS involvement, was recorded in 6 (12.2%) patients. The diagnosis was confirmed in the first initial stage in 12% of patients and during the second ME stage in the remaining 37 (75.5%) patients. Active immunization against TBE was not conducted in any patient.

CONCLUSION

We report on the first patients diagnosed with an abortive type of TBE virus infection in the Koprivnica-Krizevci County. The frequency of and new knowledge about this type of disease were assessed in the study.