Correlation of TBE Incidence with Red Deer and Roe Deer Abundance in Slovenia

Tick-borne encephalitis (TBE) is a virus infection which sometimes causes human disease. The TBE virus is found in ticks and certain vertebrate tick hosts in restricted endemic localities termed TBE foci. The formation of natural foci is a combination of several factors: the vectors, a suitable and numerous enough number of hosts and in a habitat with suitable vegetation and climate. The present study investigated the influence of deer on the incidence of tick-borne encephalitis. We were able to obtain data from deer culls. Using this data, the abundance of deer was estimated and temporal and spatial analysis was performed. The abundance of deer has increased in the past decades, as well as the incidence of tick-borne encephalitis. Temporal analysis confirmed a correlation between red deer abundance and tick-borne encephalitis occurrence. Additionally, spatial analysis established, that in areas with high incidence of tick-borne encephalitis red deer density is higher, compared to areas with no or few human cases of tick-borne encephalitis. However, such correlation could not be confirmed between roe deer density and the incidence of tick-borne encephalitis. This is presumably due to roe deer density being above a certain threshold so that availability of tick reproduction hosts has no apparent effect on ticks'' host finding and consequently may not be possible to correlate with incidence of human TBE.     

The clinico-epidemiological characteristics of Powassan encephalitis in the southern Soviet Far East]

The present communication deals with the analysis of 14 cases of Powassan encephalitis. As shown in this study, the course of this infection may be accompanied by symptoms indicating the presence of cerebral and meningeal lesions (in 7 cases meningoencephalitic forms with one fatal outcome and in 2 cases meningeal forms were registered) or take febrile and inapparent forms (5 cases). Powassan encephalitis was found to give characteristic symptoms of cerebellovestibular lesions, differentiating this disease from tick-borne encephalitis (TBE). The cases of mixed infections caused by TBE virus, Powassan encephalitis virus and tick-born Borrelia were found to be possible.     

The immunodiagnosis of tick-borne encephalitis by using the indirect immune rosette formation reaction

200 patients suspected for tick-borne encephalitis (TBE) were examined by the method of the indirect immune rosette-formation test. In 70.15% of patients with the serologically confirmed diagnosis of TBE immune lymphocytes were detected as early as on day 1 of examination. The level of rosette formation was higher in the meningeal form of the disease. Rosette-forming lymphocytes were also detected in 24.06% of patients with the serologically unconfirmed diagnosis of TBE. The test is proposed for the early diagnosis of TBE.     

The immune status of the population of the Crimea to the tick-borne encephalitis virus]

The immune status of the Crimean population with respect to tick-borne encephalitis (TBE) virus has been studied. The results of the study confirm the existence of natural foci of TBE in the Crimea. The most active and potentially dangerous foci are located in forests of the mountain area of the peninsula. The study has revealed that humans are mainly exposed to the risk of contacting TBE virus infection during their work and rest in the forest.     

Relationships between the content of circulating immune complexes, the concentration of serum immunoglobulins and the titers of specific antibodies in patients with tick-borne encephalitis

In the blood serum of tick-borne encephalitis (TBE) patients the detection rate and concentration of circulating immune complexes, as well as the content of serum IgA, IgM and IgG, were evaluated. The formation of immune complexes was found to depend on IgM and IgG specific antibodies to TBE virus, the period of the disease and the clinical form of virus infection.     

The relationship of the antigenic characteristics of the tick-borne encephalitis virus to the level of the protective activity of inactivated cultured vaccines]

As shown in this study, the immunization of animals with killed vaccines against tick-borne encephalitis (TBE) leads to the formation of specific immunity, depending on the antigenic structure of the vaccine strain and the test strains used for challenge. Vaccines obtained on the basis of the TBE virus strain of the Eastern antigenic variant induced the development of a wider spectrum of specific protective activity than vaccines obtained on the basis of the TBE virus strain of the Western antigenic variant.     

Tick-borne encephalitis virus prevalence in Ixodes ricinus ticks collected in high risk habitats of the south-Bohemian region of the Czech Republic

A survey for tick-borne encephalitis virus in Ixodes ricinus ticks was conducted in May 2000 in two districts of the South-Bohemian region of the Czech Republic with a high occurrence of tick-borne encephalitis (TBE) in humans. Homogenized ticks were tested on PS cells, which were examined for any cytopathic effect, plaque assay and indirect fluorescent antibody test (IFT). The IFT has proved to be the most sensitive and most rapid test to demonstrate the virus in ticks. TBE virus was found in 17 of 187 pooled samples, consisting of a total of 2,968 ticks. The mean minimum infection rate was 0.6% for all tick stages combined. Infection rates in nymphs collected indifferent locations varied between 0.2 and 1.3% and between 5.9 and 11.1% in adult ticks. The observed TBE prevalence in ticks was compared with data obtained elsewhere in the Czech Republic. It is concluded that screening of ticks for TBE virus prevalence using IFT is a valuable indicator for the degree of risk to contract TBE in as particular habitat. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tick-borne encephalitis in the Estonian SSR

The foci of tick-borne encephalitis (TBE) of 2 types, differing in their morbidity rates, the character of their immunological structures, the species composition of carrier mites and their capacity for TBE virus carriership, have been shown to exist in Estonia. TBE morbidity is characterized by 4- to 5-year cycles, the overwhelming majority of TBE cases being registered in the area of the joint habitat of both species of mites. During the epidemic season 2 peaks of morbidity rise are registered, which corresponds to peaks in the number of mites in nature. Different epidemic importance of 2 species of carrier mites in TBE morbidity in Estonia has been shown.     

Characteristics of lipids imbalance in patients with tick-borne encephalitis

Using a novel approach, we have analyzed 30 parameters characterizing detailed spectrum and fractional content of LPs in plasma of patients with tick-borne encephalitis (TBE). The blood plasma of all TBE patients (30 patients), as compared with that of healthy individuals (120 patients), is characterized by decreased concentrations of many LP subfractions and of the total concentration of all plasma LPs (hypolipoproteinemia). The observed difference in some parameters was statistically significant. Using computer-assisted factor analysis, we have shown that according to these 30 parameters TBE patients are similar to patients with multiple sclerosis and systemic lupus erythematosus. The results provide grounds for using data on blood plasma LPs as additional criteria for diagnosis of TBE.     

Tick-borne encephalitis in the Maritime Territory

On the basis of epidemiological analysis carried out at the period of 1940-1987, a decrease in tick-borne encephalitis (TBE) morbidity was registered; at the same time time the disease invariably took, as before, a clinically severe course. The most dangerous foci of TBE were found to be located in the southern Okhotsk region grown with dark coniferous forests. The subsiding and activation of the natural foci of TBE in different regions of the territory were established and some heretofore unknown foci in southern regions of the Maritime Territory were found. Ixodes mites inhabiting the Maritime Territory were shown to have a low level of virus carriership, thus causing the low level of population immunity to TBE virus. Combined foci of TBE and Powassan encephalitis were found.     

Antibodies to DNA in the Blood of Patients with Tick-Borne Encephalitis

The relative levels of autoantibodies to native and denatured DNA (nDNA and dDNA, respectively) in the blood were compared in 55 patients with tick-borne encephalitis (TBE). Compared to healthy donors, the titers of antibodies (Ab) to nDNA and dDNA were significantly higher in 31% and 40% of TBE patients, respectively. The proportion of patients with an increased concentration of anti-nDNA Ab in the case of TBE (32%) was higher than among patients with multiple sclerosis (18%) and some other autoimmune diseases (6–18%) but comparable with that among patients with systemic lupus erythematosus (38%) and polymyositis (42%). In contrast to the patients with systemic lupus erythematosus and multiple sclerosis, the level of antibodies to nDNA in TBE patients was higher than that of anti-dDNA Ab. The coefficients of correlation between the levels of Ab to nDNA and dDNA were estimated for the entire group of TBE patients and for subgroups with different forms of the disease (temperature reactions, febrile form, and meningeal form). Analysis of correlation between the anti-DNA antibody titers and three standard biochemical markers of TBE (aspartate aminotransferase and alanine aminotransferase activities and total bilirubin) was carried out for 22 patients. A statistically significant correlation was revealed only between the level of Ab to nDNA and the marker enzyme activities, with the respective correlation coefficients being +0.44 and +0.48, respectively.     

The protective activity of preparations made from the tick-borne encephalitis virus grown using different cell cultures]

The preparations of tick-borne encephalitis (TBE) virus grown in swine embryo kidney cell culture have been shown to possess pronounced protective activity per unit of virion protein E in comparison with TBE virus preparations derived from cell culture 4647 and chick embryo cell culture. The antigenic activity of all virus preparations under study has proved to be practically the same. The role of post-translation modifications of TBE virus protein E in the manifestation of some of its biological properties is discussed.     

Arboviruses in birds captured in Slovakia.

Virus neutralizing (VN) antibodies against Sindbis, tick-borne encephalitis (TBE), West Nile (WN), Tahyna and Calovo viruses were found in birds captured in Slovakia. In parallel, Sindbis, TBE and WN viruses were isolated from the blood, brain and liver of migrating birds.     

Ixodes tick-borne borreliosis and tick-borne encephalitis in the Udmurt republic: retrospective analysis of their spread

The primary clinical-anamnestic and laboratory data on 1,062 cases, registered in Udmurtia in 1965-1968 and caused by the bites of taiga ticks (ixodes persulcatus), were retrospectively analyzed. The study revealed that not less than 27% of these cases could be regarded as cases of Ixodes tick-borne borreliosis (ITBB); formerly they were classified with tick-born encephalitis (TBE) or diseases of unclear etiology. The spread of ITBB on the territory of the Udmurt Republic was shown to be similar to that of TBE.     

The protein admixture content in a tick-borne encephalitis vaccine and its purification by means of microfiltration]

The method of rocket immunoelectrophoresis permits the detection of all antigenic admixtures in tick-borne encephalitis (TBE) vaccine. Human serum albumin constitutes the main part of protein admixtures in the preparation. Purification by microfiltration is an effective stage of the technological process of obtaining purified TBE vaccine.     

Comparative ecology and epidemiology of lyme disease and tick-borne encephalitis in the former Soviet Union

The recently defined range of human Lyme disease in Russia coincides with that of the intensively studied agent of tick-borne encephalitis (TBE). Although identical vectors transmit both infections during the same seasons and in the same locations, more than twice as many people suffer from Lyme disease as from TBE. Edward Korenberg here describes characteristic features of vectors with respect to their seasonal activity, abundance, rates of infection by TBE and Lyme disease agents, as well as incidence of human-tick contact, and how these factors determine the incidence of TBE and Lyme disease in different regions.     

Clinico-epidemiological characteristics of tick-borne encephalitis in the Maritime Territory

Clinico-epidemiological analysis of tick-borne encephalitis (TBE) incidence rate in the Primorski Territory for 25 years has revealed the prevalence of focal forms of this infection (on the average, 50%) and its high mortality rate (on the average, 33% for the focal forms and 6.4% for the meningeal form). Such course and termination of this infection depend not only on the reactive capacity of the patient's body, but, to a great extent, on the virulence of TBE virus circulating in the area under study.     

森林脑炎自然疫源地样本的监测及病毒的分离研究

为了解森林脑炎疫源地的分布变化趋势及样本分离病毒的特性,采集了森林脑炎高发区周边的森林全沟硬蜱、血蜱样本及森林脑炎患者的脑组织样本,用小白鼠脑内接种法检测、分离病毒分离的病毒经鉴别试验证明为森林脑炎病毒：蜱、脑两种标本检测的阳性率分别为50％和100％、结果表明森林脑炎的疫区有从林区向农业区扩散的趋势,且全沟硬蜱的带毒率较高;森脑患者的脑组织样本与蜱标本病毒的性状育差异     

Tick-borne encephalitis in a northern zone of coniferous and broad-leaved forests of a focal region of the Amur River basin

The geographical variability of the population of tick-borne encephalitis (TBE) virus in the northern part of the zone of combined coniferous and broad-leaved forests was established; this variability was manifested by higher virulence and homogeneity of TBE virus strains, as shown in experiments on white mice receiving the virus extraneurally, in comparison with the southern part of the zone and by higher virus carriership of the ticks Ixodes persulcatus. With the epizootic situation remaining tense and the danger of TBE virus infection still present, TBE morbidity and mortality rates decreased in the years of the construction of the Baikal-Amur Railroad, which was due to greater attention given to measures for the prophylaxis of TBE during this period.     

Characterization of monoclonal antibodies against Hokkaido strain tick-borne encephalitis virus

A tick-borne encephalitis (TBE) patient was found in Hokkaido in 1993, and TBE viruses were isolated from animals and ticks in our previous studies. To develop a diagnostic reagent to identify TBE viruses, monoclonal antibodies (Mabs) were produced against the TBE virus strain Hokkaido (Oshima 5-10). Seven Mabs were obtained which reacted with the envelope protein of the Oshima 5-10 strain. These Mabs were flavivirus genus-specific, TBE virus complex-specific or TBE virus type-specific. The Mabs are applicable for identification of TBE virus strains.