Mild cognitive impairment after Tick borne encephalitis

Abstract

Tick-borne encephalitis (TBE) is potentially debilitating disease caused by virus called TBEV (Tick Borne Encephalitis Virus). It is transmitted by the bite of a tick. Tick borne encephalitis used to have wide distribution, including Europe and Asia. Natural foci of TBE had been localized in Lublin region of Poland as well. According to the databases of the Department of Occupational Biohazards of Institute of Agricultural Medicine, they had observed an increase in the incidence of tick-borne encephalitis in the Lublin region from the early of 1990's. Since the beginning of the year 2001, all the patients who contracted tick-borne encephalitis in Lublin's region were examined. Only patients who had been suffering from tick-borne encephalitis for the last seven years were included to the study. Long lasting cognitive consequences of the illness have been noticed. Of the original 38 patients, 21 persons (all under 55 years of age) were diagnosed with cognitive impairment similar to that observed as the pre-dementia period of the Alzheimer's disease. Cognitive decline could have been diagnosed as mild cognitive impairment according Petersen et al. criteria. The decline of the cognitive status hasn’t been observed in examined patients with. Moreover neither improvement nor decline has been observed in this group after six months. Diagnosis of human TBE is usually based on serology, which has a number of pitfalls. Thus the preferred diagnosis is still based largely on clinical findings. The outcome of the disease could also mimic many neurological diseases. Consequently, the history of the patient with cognitive decline should be carefully examined especially in the endemic regions for TBE.