Epidemiology of Tick-Born Encephalitis and it's Clinical Manifestations in Panevèzys City County

Violeta Dambrauskienè, Eugenijus Preidis

Lietuvos Respublika, Panevèzio Apskrities Virðininko Administracija, VIEÐOJI ÁSTAIGA, PANEVÈZIO INFEKCINÈ LIGONINÈ, Ramygalos g. 25, 5319, Panevèzys, Lietuva (Lithuania)

Man and tick have been living side by side for ages, but the more destructive interaction began only some years ago when ticks brought to our country infections diseases, that were unknown to us or were very rare indeed until the recent years. Although people suffered from them in America and Siberia for many ages. TBE was, clinically diagnosed in Lithuania in 1953. It is, perhaps, due to the global climate changes and changes in the types of forests, as well as to the longer period of the tick reproduction in Their life circle, that increases the risk of infection with TBE and LB. Ticks spread around very fast all throughout Lithuania and they attack people not only in the wild forests but also in the parks and gardens situated in the outskirts of the towns and even in the green areas of the city centre.

DATA ANALYSIS

1. Incidence of TBE is steadily increasing in Lithuania from 1993 (200 cases) to 2000-418 cases a year. Only in 1999 there was a sudden decrease in morbidity, which is probably related to the exceptionally hot and dry summer that year in Lithuania

2.Incidence of TBE remains on the same level all through these years in Panevèzys County: 1994-85, 1999-110, 2000-84 cases a year. The problem is that this county covers about 1\10 of Lithuania's territory but about 1\4 of all cases of TBE in Lithuania are diagnosed in this region.

3.Analysis of the data collected in 1999\2000 shoved that 2\3-3\4 of all cases of TBE in Panevèzys County were recorder in Panevèzys City and region, i.e. there were 68 cases in Panevèzys City and region and only 10 cases in other towns and cities of the county in 1998. The epidemiological data at the same time shows that infected ticks are equally spread all throughout the territory of the County; this indicates that there could be some problems with the diagnoses of TBE in smaller hospitals.

RESULTS

1. We have completed the retrospective analysis of 72 cases histories of patients treated for TBE in Panevèzys Infections Disease Hospital in 2000. We do not believe it is a profound study since the data was collected the standard, documentation and there was a lack of laboratory tests and instrumental examinations due to the financial difficulties faced by the hospital last year, there fore some data might be incomplete.
    

2. Analysis of the epidemiological data on TBE in Panevèzys city and County shows that it can be influenced by the diagnostic difficulties. It is probably due to this fact that about 2\3-3\4 of all cases of TBE in Panevèzys County is diagnosed in specialised Infectious Diseases Hospital of Panevèzys City and might be unrecognised in some smaller or unspecialised institutions.
    

3. The largest incidence of TBE is among the adults of 31 to 70 years of age (71,99%), in the age group 31-55-32 cases (44,44%), age group 51-70 -22 cases (30,55%). We believe these people work in the gardens and fields more often; they also visit forests and gather berries and mushrooms. There also could be the case that small children have less distinct clinical presentation of TBE and more atypical manifestation of the infection, 10 these cases are not diagnosed as TBE.
    

4. 60 patients (83,33%) knew that a tick bit them, 3 of 72 (4,17%) were consuming goat milk and the rest of the patients admitted that they were in the forest and \or garden (12,5%), but haven't noticed the bites of a tick. Russian literature presents facts about people who were infected with TBE while drinking the goat milk. We were interested in this idea and decided to make a clinical observation concerning such a problem and last year we finally were presented with the case when all of the family was infected with TBE from the goat milk. We believe it is dangerous to consume raw goat milk in the territories heavily inhabited by the infected ticks. If ticks bite goats often, the concentration of viruses reaches the dangerous level.
    

5. Analysis of the case history of this family also proved that TBE can manifest in different ways: 1 of 7 family members had meningoencephalomyelitis, 1-TBE meningitis, 2 children presented with TBE which reminded of viral respiratory tract infection and 3 members of the family had no signs of infection since the did not drink the goat milk.
    

6. TBE was diagnosed in 72 cases in Pangenesis Infections Disease Hospital and it was confirmed by ELISA method in 72 cases (100%) using the test to identify antibodies of IgM class for TBE. 24 patients (33,33%) were also tested for IgM and IgG class antibodies against Borrelia burgdorferi and 7of them (29,17%) had antibodies for both B. burgdorferi and TBE virus, this implies that ticks can be infected with both contagious agents, therefore it might be useful to test patients for both of them, if the patient presents with meningeal signs, neurological symptoms and high fever.
    

7. Typical clinical manifestation includes these symptoms according to our case analysis:
   - High fever (39-40° C) -72 cases (100%)
   - Two waver fever - 58 cases (10,56%)
   - Tremor of tongue, lips, palpebra and hands- 63 cases (87,5%)
   - Coordination disorders -41 cases (56,94%)
   - Consciousness disturbance - 31 cases (43,05%)
   (Level of awareness)
   - Coma - 5 cases (6,94%)
   
   Meningeal signs, on the other hand, had very little clinical significance even when serum or CSF
   changes prove the diagnoses of TBE:
   - No meningeal signs -18 cases (25%)
   - Weak neck rigidity-19 cases (26,39%).

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