Severe Tick-Borne Encephalitis (TBE) in a Patient with X-Linked Agammaglobulinemia; Treatment with TBE Virus IgG Positive Plasma, Clinical Outcome and T Cell Responses

PURPOSE

A patient with X-linked agammaglobulinemia (XLA) and severe tick-borne encephalitis (TBE) was treated with TBE virus (TBEV) IgG positive plasma. The patient's clinical response, humoral and cellular immune responses were characterized pre- and post-infection.

METHODS

ELISA and neutralisation assays were performed on sera and TBEV PCR assay on sera and cerebrospinal fluid. T cell assays were conducted on peripheral blood the patient and five healthy vaccinated controls.

RESULTS

The patient was admitted to the hospital with headache and fever. He was not vaccinated against TBE but receiving subcutaneous IgG-replacement therapy (IGRT). TBEV IgG antibodies were low-level positive (due to scIGRT), but the TBEV IgM and TBEV neutralisation tests were negative. During hospitalisation his clinical condition deteriorated (Glasgow coma scale 3/15) and he was treated in the ICU with corticosteroids and external ventricular drainage. He was then treated with plasma containing TBEV IgG without apparent side effects. His symptoms improved within a few days and the TBEV neutralisation test converted to positive. Robust CD8+ T cell responses were observed at three and 18-months post-infection, in the absence of B cells. This was confirmed by tetramers specific for TBEV.

CONCLUSION

TBEV IgG-positive plasma given to an XLA patient with TBE without evident adverse reactions may have contributed to a positive clinical outcome. Similar approaches could offer a promising foundation for researching therapeutic options for patients with humoral immunodeficiencies. Importantly, a robust CD8+ T cell response was observed after infection despite the lack of B cells and indicates that these patients can clear acute viral infections and could benefit from future vaccination programs.

Tick-borne Encephalitis Identified in Ireland: Diagnosis and Outcome

Presentation Tick borne encephalitis (TBE) is not endemic in Ireland and diagnostic tests are seldom requested. We describe the first notified case in Ireland. A 50-year-old female returned from Lithuania and presented with fever and new neurologic signs. Diagnosis TBE was diagnosed by detection of TBE virus specific antibodies in serum and cerebrospinal fluid (CSF). Treatment The patient was managed with observation and supportive care consisting of intravenous fluids and analgesia. Discussion The case highlights the importance of awareness of TBE among physicians and travellers to guide appropriate testing and vaccination. TBE is being recognised in non-endemic countries posing an emerging risk to public health.

Tick-borne encephalitis in Europe: a brief update on epidemiology, diagnosis, prevention, and treatment

Tick-borne encephalitis (TBE) is an emerging health threat that is spreading in many parts of Europe. The mix of socio-economical, ecological and climatic factors as well as the presence of more susceptible hosts is actively contributing to the increasing number of TBE reported cases. TBE is an important cause of central nervous system (CNS) infection that can result in long-term neurological sequelae and even death. Diagnosis of TBE relays mainly on high clinical suspicion confirmed by serological and molecular assays both on serum and cerebrospinal fluid (CSF) with an ancillary role for neuroimaging in supporting the diagnosis. No specific antiviral treatment is currently available for TBE; indeed, supportive treatment as well as intensive care and assisted ventilation in severe forms may be needed. Because of limited option for TBE treatment, of crucial importance is effective vaccination to prevent disease-related morbidity and mortality. Due to expanding proportion of subject possibly exposed to TBE (and new populations such as: unaware travellers to TBE-endemic areas and immunocompromised patients), we performed a comprehensive review of TBE epidemiology, clinical presentation, current available diagnostic tools and treatment.

[Tick-borne encephalitis--an update]

Tick-borne encephalitis (TBE) is a systemic infectious disease with nonspecific symptoms and/or severe neurological disorders such as meningitis, encephalitis and myelitis. The disease is caused by TBE virus, an enveloped RNA virus belonging to the family of flaviviruses. Three subtypes are currently present in different parts of Europe and Asia. The TBE virus is transmitted to humans primarily by the tick bite of Ixodes species such as I. ricinus, but also by the ingestion of contaminated raw milk and raw milk products. In Germany, more than 75% of all TBE cases occur in Bavaria and Baden-Württemberg (southern Germany). Depending on the region, 1 to 4% of adult I. ricinus ticks in southern Germany are infected with the central European TBE virus variant. Treatment of TBE is symptomatic and supportive, a specific antiviral therapy does not exist. TBE cases acquired in central European countries have usually a good prognosis. Mortality rates above 2% have been documented in cases of tick-borne encephalitis in the elderly. In endemic areas, active immunization with inactivated TBE virus vaccines provides the most secure protection against TBE. In addition, exposure prophylaxis (protection against tick bites) plays a crucial role for TBE prevention.

Epidemiological and clinical features of tick-borne encephalitis in north-western region in Belarus

THE PURPOSE OF THE STUDY

to present epidemiological features and clinical manifestations of TBE in patients residing in Grodno region.

MATERIALS AND METHODS

A retrospective analysis of 124 case histories of patients with TBE in “Grodno Regional Infectious Clinical Hospital” in 2010 – 2014.

RESULTS

Epidemiological features of tick-borne encephalitis are the prevalence of the transmission mechanism of contamination (57.3%), involvement of residents of Grodno and Grodno region (54.2%) of middle age (46.6±3.5 years) in the epidemic process. Clinical features of the illness in 124 patients were the prevalence of moderate forms of the illness (72%) in the form of meningeal (34.6%) and common infectious (29%) clinical cases.

CONCLUSIONS

Over the last 5 years in Grodno region an increased incidence of tick-borne encephalitis exceeding republican indices has been established. Among clinical cases there is an increase in severe forms of neuroinfections and mixed tick-borne.

[Tick-borne encefalitis - pathogenesis and -therapeutic approaches]

Tick-borne encephalitis (TBE) is a major public health threat in large areas of Central and Eastern Europe and in Russia. This review summarizes the current data on the interactions between the TBE virus and the host, with a particular focus on the mechanisms of neuronal injury, immune response and immunopathology in the central nervous system (CNS), and factors that determine the course and outcome of TBE. Novel trends of experimental therapy of TBE are discussed. Combining small molecule inhibitors targeting viral replication with immunomodulatury agents might be a way to maximize viral clearance and minimize immunopathology in the CNS during TBE.

Psychiatric aspects of herpes simplex encephalitis, tick-borne encephalitis and herpes zoster encephalitis among immunocompetent patients

The psychopathological symptoms occurring in the course of diseases associated with infections are often initially isolated and non-characteristic, and may cause diagnostic difficulties. Moreover, such disorders tend to be less responsive to psychiatric management. Among possible causes such as trauma, neoplasm and vascular changes, inflammatory changes of the brain as a result of a viral infection should also be considered. There were 452 registered cases of viral encephalitis in Poland in 2010, and although not very prevalent they remain a severe and life-threatening condition. What is more, the frequently occurring neurological and psychiatric complications of viral encephalitis often result in permanent disabilities, causing a significant decrease in the quality of life. This article presents the three types of encephalitis that are most prevalent among immunocompetent patients in Poland, i.e. herpes simplex encephalitis (HSE), tick-borne encephalitis (TBE) and herpes zoster encephalitis (HZE). The psychopathology of the acute phase of the infection, the residual symptoms, features apparent in imaging studies and some neuropathological aspects are also presented. The paper also focuses on psychiatric aspects of the diagnostics and treatment of the described conditions. The clinical pictures of these infections are quite specific, although they cover a wide range of symptoms, and these characteristic features are described. The aim of this review is also to show the significance of thorough diagnostics and a multidisciplinary approach to patients with viral CNS infections.

[Vaccines, immunoglobulins, and test systems for the prevention and diagnosis of tick-borne encephalitis]

The quality of drugs used in the Russian Federation to prevent and diagnose tick-borne encephalitis (TBE) was analyzed. The TBE vaccines made in Russian were shown to be as effective as those manufactured in foreign countries and to have the similar production techniques and quality indices therefore they may be interchangeable in the population's vaccination. The specific activity of has recently increased in terms of the content of TBE virus antibodies. In Russia, a wide range of enzyme immunoassay systems have been designed and manufactured for the detection of human serum (plasma) IgM and IgG antibodies to TVE virus and for that of TBE viral antigen in the biological objects, primarily in the ticks.

[Prevention of tick-borne encephalitis at the present stage: strategy and tactics]

The paper discusses the prevention of tick-borne encephalitis (TBE) under the conditions of a varying epidemiologic situation. High mortality, a change in its structure, an expansion of a nosological area, an increase in the number of anthropurgic foci in the suburbs and towns and cities, the detection of combined foci and the development of mixed forms of tick-borne infections, and clinical pathomorphism suggest that novel approaches to preventing this severe viral disease are urgent. The comprehensive nature of a prophylaxis system should envisage the use of tried-and-true specific and nonspecific measures against the entire group of tick-borne infections. Cohort vaccination should be considered as a priority measure in high TBE endemic areas. The prophylaxis system should be differentiated and adequate to the specific epidemic situation in the endemic regions.

[Epidemiology of tick-borne diseases in Poland]

The paper summarizes state of art knowledge on tick-borne diseases epidemiology in Poland. The most prevalent diseases are Lyme borreliosis (LB) and tick-borne encephalitis (TBE). Although there is growing number of data published on anaplasmosis and babesiosis prevalence in ticks and humans, there is no national data on these diseases and their epidemiological features remain unclear. All tick-borne agents have a common vector tick--the sheep tick Ixodes ricinus. LB and TBE are mandatory reportable diseases. In 2005 case definitions were implemented in Poland to allow a better comparability of data within the country and with other European countries. LB is widespread in Poland. Studies of prevalence of infected ticks indicate that from 6 to 15% of I. ricinus ticks in different sites are infected with the spirochete. Data from seroepidemiologic studies and from routine surveillance (started in 1996) confirm that the disease is widespread in Poland, and its incidence is increasing. It has increased from 2.31 per 100,000 in 1999 to 11.55 in 2005. One reason of this increase is the improvement in diagnosis of the disease. There is a need to promote personal protection during outdoor activities and knowledge on LB symptoms, especially among populations at risk--forestry workers, farmers. TBE incidence is limited to two main foci--one in the Northeast of Poland bordering Baltic states endemic region, and the second on the South of Poland, neighbouring the Czech and Slovak republics. Seroepidemiologic data, supported by surveillance data, indicate that there are areas of particularly high TBEV activity. The mostly affected occupational groups are: unemployed, retired, students, and farmers. This is a reason to promote personal protection and prophylactic vaccination of both inhabitants of endemic regions and tourists visiting endemic regions.

[Tick-borne encephalitis (FSME)--how great is the danger really?]

Tick-borne encephalitis is a neurotropic viral disease transmitted by ticks, and occasionally by the drinking of milk. Its incidence in Central and Eastern Europe has increased sharply, supposedly due--among other things--to climate warming and changes in leisure activities. The probability of contracting the disease following viral infection is about 30%. Some 70% of victims manifest a biphasic course with two fever peaks. Some 10% will have lasting, sometimes severe, neurological deficits, and 1 to 2% will die. The diagnosis is based on confirmed exposure to ticks in a high-risk area, a tick bite within the previous three weeks, clinical symptomatology, infected CSF, and FSME-specific IgM and IgG antibodies in the serum. Causal treatment is not possible, but the disease can be effectively avoided by prophylactic (anti-exposure) measures and vaccination. The vaccines currently available in Germany are highly effective and well tolerated, and a vaccine for children became available in 2002. Medical counselling of travellers should give consideration to vaccination against the condition--in particular for destinations in the south east or east of Europe.

[Problems of differential diagnosis in tick-borne encephalitis-induced polyradiculitis]

In about 10% of cases, tick-borne encephalitis (TBE) presents with additional myeloradiculitic features mimicking acute poliomyelitis, which can rarely appear as the sole symptom. We report on a 59-year-old man infected with TBE in Thuringia,Germany, who developed polyradiculitis with rapidly progressive, predominantly proximal tetraparesis and respiratory failure. We discuss the differential diagnosis and the epidemiological relevance in conjunction with a second typical case of TBE acquired in the same region and time period.

[Quadriplegia and prolonged respiratory insufficiency due to tick-borne encephalomyelitis. Case report]

Tick-borne encephalitis (TBE) is an uncommon and potentially severe illness. TBE virus is transmitted to the humans by an infected tick and it spreads to the central nervous system determining various clinical pictures. A case in which TBE virus caused an encephalomyelitis with quadriplegia and respiratory insufficiency that persist one year after the diagnosis, is reported. Such a clinical manifestation of TBE has never been described in Italy till now.

Tick-borne encephalitis (TBE) in dogs

Tick-borne encephalitis (TBE) is caused by a Flavivirus and transmitted by ticks. It is known in dogs for nearly 30 years and the number of TBE cases is increasing. In addition to fever, cerebrocortical, thalamic, and brainstem symptoms occur simultaneously. Not all TBE infections in dogs lead to clinical signs but peracute/lethal as well as subacute and chronic courses have been reported. TBE is a seasonal disease, depending on climate related tick activity. Infected ticks are spreading the virus over central Europe with a tendency to expand to new endemic areas in western Europe.

Pharmacokinetics of human tick-borne encephalitis virus antibody levels after injection with human tick-borne encephalitis immunoglobulin, solvent/detergent treated, FSME-BULIN S/D in healthy volunteers

This study assessed tick-borne encephalitis virus (TBEV) neutralizing antibody levels after injection of FSME-BULIN S/D (human tick-borne encephalitis immunoglobulin; 0.2 ml/kg body weight) in healthy volunteers. After screening of 18 volunteers for TBEV antibody titers, 12 healthy volunteers with TBEV antibody titers < 5 were entered into the pharmacokinetic part of the study. TBEV antibody titers were analyzed before injection and after 24 h, 48 h, 3 d, 4 d and 8 d. Vital signs, adverse events and laboratory tests for safety were analyzed after intramuscular injection with the immunoglobulin at 4 sites in the gluteal muscles. Injection with 0.2 ml/kg of FSME-BULIN S/D induced a fast increase in, and sustained titers of, neutralizing antibody levels against TBEV. The injections were well tolerated and the safety profile of the product was fully acceptable.

[Clinical pathogenic peculiarities of chronic Russian tick-born encephalitis]

Clinical, serologic, epidemiological and neurological studies were carried out in 23 patients (18 men, 5 women) aged 15-69 years who had chronic Russian tick-borne encephalitis (RTE). With permanent stable humoral immunity the fact that these forms might develop was confirmed in 73.9% of the cases. In 26.1% of the patients were found to have incomplete vaccination and vaccine therapy combined with RTE viral infection. The following conditions underlay chronization were observed in all forms of acute RTE: fever in 4.3%, meningitis in 30.4%, focal lesion in 43.5% (the encephalitic syndrome in 8.7%, poliomyelitis in 8.7%, encephalopoliomyelitis in 26.1%). Initially progressive course was found in 21.7% of the cases. There was a primary rise of the hyperkinetic syndrome after the meningeal and focal forms of RTE with the encephalitic syndrome; while development of the amyotrophic syndrome (ATS) was found after the focal form with the poliomyelitic and encephalopoliomyelitic syndrome. The amyotrophic lateral sclerosis (ALS) syndrome occurs as both primary progressive RTE and ATS transformation independently of the initial RTE form. Latent periods of development of ATS and ALS syndrome were virtually equal (mean 1.4 years) and did not depend on the initial form of acute RTE. The duration of development of latent chronic forms makes it necessary to follow up RTE patients for at least 3 years.

[Tick-borne meningoencephalitis in Thurgau Canton: a clinical and epidiomological analysis]

BACKGROUND

Tick-borne meningo-encephalitis (TBE) is caused by a flavivirus species that is transmitted from rodents to humans by Ixodes ticks. The clinical picture of central nervous system involvement varies from febrile headache to lethal encephalitis. To date no specific treatment exists, although protective active immunisation is available.

METHODS

We present the clinical and epidemiological data from 73 patients with TBE who acquired the infection in Canton Thurgau in the years 1996-1999.

RESULTS

Canton Thurgau is a state in eastern Switzerland with a population of 230,000. Within the last five years the reported cases of TBE have increased more than threefold. The area where infectious tick bites were registered has expanded from the western to the eastern part and now encompasses the entire state. The risk of infection is clearly related to frequent activities in wooded areas, though outdoor activities not in forests also carry a considerable risk. In > 80% of the cases a postviral neurasthenic syndrome develops involving absence from work for two months on average. In the elderly and patients who present with encephalitic symptoms, a worse outcome with persistent neurological symptoms or even death has been observed.

CONCLUSION

The increasing incidence of TBE, the expansion of infectious ticks to the east and high morbidity justify active immunisation against TBE on a broad scale in Canton Thurgau.

[Evaluation of FcR and CR receptor expression in granulocytes and immune complex level in patients with tick-borne encephalitis (TBE)]

The aim of this study was to estimate expression of FcR and CR membrane receptors of PMN and circulating immune complexes level in serum from infected patients before and after treatment. Before treatment we observed significant decrease of PMN percentage with FcR and CR receptors in comparison to control. After treatment there was increase of PMN percentage with receptors in comparison to values before treatment but it did not reach values of controls. Immune complexes level before treatment was significant higher than controls before treatment and it decreased after treatment but did not reach control level. Depression of phagocytic activity of PMN may be one of the main reasons for spreading viral infection.

[Experimental tick-borne encephalitis in golden hamsters treated with specific immunotherapy]

Efficiency of various protocols of specific immunoglobulin treatment was evaluated in golden hamsters inoculated with two Far Eastern tick-borne encephalitis (TBE) strains. After a low therapeutic dose (0.1 ml) of immunoglobulin, corresponding to total dose (60 ml) per course, all parameters (survival, immunogenicity, pathomorphology of the brain) deteriorated in animals infected with both strains. A higher dose (0.2 ml) corresponding to total dose of 120 ml notably improved all the studied parameters. The efficiency of specific immunoglobulin depends on the clinical and pathogenetic characteristics of TBE, determined by the properties of TBE strains. The results validate therapy and prevention of TBE by high-titer immunoglobulin in adequate total dose, monitored by blood analyses for TBE antigen and evaluations of the time course of IgM antibodies.

Tick-borne encephalitis

Tick-borne encephalitis (TBE) is a zoonotic arbovirus infection endemic to Russia and Eastern and Central Europe. Despite being a common and serious life-threatening disease for which a mass vaccination program was implemented in Austria, there is only limited reference to this disease in the English-language literature. TBE is transmitted to humans usually by the bite of a tick (either Ixodes persulcatus or Ixodes ricinus); occasionally, cases occur following consumption of infected unpasteurized milk. Transmission is seasonal and occurs in spring and summer, particularly in rural areas favored by the vector. TBE is a serious cause of acute central nervous system disease, which may result in death or long-term neurological sequelae. Effective vaccines are available in a few countries. The risk for travelers of acquiring TBE is increasing with the recent rise in tourism to areas of endemicity during spring and summer.

[Concentrations of tumor necrosis factor alpha and interleukin-1 beta in cerebrospinal fluid in the course of tick-borne encephalitis]

CSF concentrations of TNF-alpha and Il-1 beta were detected in patients with TBE. The cytokines were detected by immunometric assay by MEDGENIX kit. CSF Concentrations of TNF-alpha and IL-1 beta in patients with TBE were significantly higher than in control group before as well as after treatment and normalization of CSF parameters. These concentrations were lower comparing to one obtained in group of bacterial meningitis. There was no correlation between concentration of cytokines and other CSF parameters (cytosis, protein, glucose concentration). Concentrations of analysed cytokines did not change significantly before and after treatment. Detection of CSF concentrations of TNF-alpha and Il-1 beta in patients with tick-borne encephalitis can be used to evaluate efficacy of treatment and retreat of infection.

[Artificial ventilation of the lungs in respiratory failure caused by lesions of the peripheral neuron]

A case with 155-day artificial ventilation of the lungs (AVL) in a patient with the poliencephalomyelitic form of tick-borne encephalitis is described. AVL was conducted through tracheostoma by the Puritan-Bennett 720ae device in the CMU mode for 26 days, then in the SIMU + PS accessory mode for 7 days, and in the CPAP + PS mode for 155 days. Despite the recovery of spontaneous respiration, vital capacity of the lungs did not normalize (1.1 liter) and the involvement at the level of the spine and the nuclei of the craniocerebral nerves was not corrected. The compensation was evidently due to training the diaphragm and the respiratory muscles and joining the accessory muscles.

[Tick-borne encephalitis in Central and Eastern Europe]

The tick-borne encephalitis virus, a major arbovirus, is endemic in Central and Eastern Europe. Since the first case of tick-borne encephalitis observed in Alsace in 1968, there have been approximately 30 cases reported in eastern France. The tick Ixodes persulcatus (and the western subtype I. ricinus) is both the main reservoir and vector of the disease. Early clinical signs of infection are followed by a second phase complicated with meningoencephalitis. The geographical distribution of the different viral subtypes would explain the variable severity of tick-borne encephalitis. Outcome may be fatal or leave major neurological sequellae. Currently, only symptomatic treatment is available, underlining the importance of prevention with anti-tick-borne virus vaccine for populations at risk living in endemic areas.

[Organizational problems of the production of biological preparations of blood]

The trend of the incidence of tick-borne encephalitis makes one pay attention to the production of blood biological preparations. A detailed programme for improving the production process, which is included into the federal and republican programmes, is outlined.

[The interferon system in acute tick-borne encephalitis and effect on the dynamics of clinical laboratory indicators using different methods of interferon therapy]

Study of the interferon system parameters, natural killer activity, and immunologic characteristics in patients with acute tick-borne encephalitis confirmed that addition of interferon preparations to combined therapy is pathogenetically justified. Reaferon was conducive to shortening of the manifest period of the disease and to alleviation of its symptoms, but it depressed its own interferonogenesis. Viferon had not only a positive impact on the time course of clinical parameters, but promoted a more active recovery of interferon production and immunologic parameters.

[Viral encephalitis after tick bite]

TBE is caused by a Flavivirus and is endemic in certain areas of Central and Eastern Europe, such as Austria, the south of Germany, Hungary, Czechoslovakia, Poland, the former Yugoslavia and SNG and certain areas of Sweden and Finland. Recent developments in the Eastern European countries have made them popular with Danish travellers, who are thus exposed to infection. Until now TBE has been a very rare disease in Denmark. The clinical course is biphasic being preceded by an incubation period of ten days. After the initial phase with uncharacteristic symptoms, a period af about five days follows where the patient has no symptoms. About one-third of the patients develop meningo-encephalitis where paresis can be seen. The course of the disease is often prolonged. The prognosis is good in terms of full recovery and low mortality. The diagnosis is made serologically with haemagglutination-inhibition test or ELISA-technique. Differential diagnosis includes other causes of viral encephalitis and Lyme disease with neurological manifestations, when there is a history of tick-bites. Vaccination provides good protection and is recommended for certain travellers with trips of some duration in endemic areas.

[Tick-borne encephalitis in the West Bohemian Region 1960-1991]

In 1960-1991 in the West Bohemian region 746 cases of tick-borne encephalitis were confirmed by serological examination. The highest morbidity was recorded in the population of Plzen--5.9 per 100,000 per year. During 1986-1991 the mean hospitalization period of patients with tick-borne encephalitis was 13.5 days. Analysis by age groups revealed the highest specific morbidity in subjects aged 15-34 years. In the limital age groups the disease was recorded only exceptionally. From data on the specific morbidity and clinical severity ensues that mass vaccination against this infection in areas with a lower risk could start in subjects older than 10 years.

[The effect of preparations of specific and nonspecific transfer-factor on the course of experimental tick-borne encephalitis]

Syrian hamsters subcutaneously inoculated with tick-borne encephalitis (TBE) virus were given transfer-factor (TF) preparations derived by different methods. The preparation of specific TF was obtained from the blood leukocytes of TBE convalescents. The nonspecific TF preparations were made of the lymphocytes of the tonsils removed from children with chronic tonsillitis outside the TBE focus. The effect of the TF preparations depended on the TBE virus strain and dose, TF preparation dosage schedule and characteristics. The specific TF preparations stimulated the development of acute fatal TBE after 3 injections at intervals of 0, 48 and 96 hours postinoculation with the virus. The preparations of nonspecific TF potentiate the infection after preliminary (24 hours) and simultaneous inoculation of the virus, producing transformation of asymptomatic infection to subacute TBE or exacerbation of the subacute process. A significant inhibition of TBE virus reproduction in spleen and brain tissues is observed after inoculation of a nonspecific TF F150 preparation 72 hours after virus inoculation, that is at the time when the virus has been already localized in the central nervous system. The results of the study indicate that the protective effect of TF is mainly associated with nonspecific immunopharmacological activity of the preparations.

[The efficacy of vaccination and serotherapy in tick-borne encephalitis in the Maritime Territory]

The use of different vaccines manufactured in the USSR under the condition of the Far East has revealed that killed vaccines do not produce a protective effect, sufficient for the prophylaxis of tick-borne encephalitis (TBE). This is probably due to the circulation of a highly virulent population of TBE virus at the Territory. This virus population may produce a severe course of infection and aggravate the clinico-epidemiological characteristics of the effectiveness of vaccines. Besides, low levels of specific and nonspecific humoral resistance factors in the residents of the Far East, especially in spring and summer, contribute to this fact. The negative effect of specific serotherapy for persons over 40 years of age has been established.

[The effect of myelopeptides on the persistence of tick-borne encephalitis virus in monkeys]

Myelopeptides (MP), bioregulatory molecules of bone marrow origin, exert a protective effect in persistence of tick-borne encephalitis virus in cynomolgus monkeys (Macaca fascicularis). The experiments involved 32 monkeys. The effect of MP was observed after one or two subcutaneous injections in a dose of 1 mg within 1.5-2 months after virus infection. The effect consists in 25-fold reduction of the frequency of virus persistence, marked limitation of the zone of spread of the persisting virus, including the central nervous system (CNS), decrease in virulence of the persisting virus, and lack of morphological signs of progress of the pathological process in the CNS. The protective effect was also observed when the infected monkeys were treated with MP and inactivated concentrated TBE vaccine. At the same time, the vaccine alone exerted a much less marked effect on the persisting TBE virus producing only a 2-fold reduction in the frequency of persistence without limitation of the zones of virus spread. In acute TBE in BALB/c mice, the effect of MP is observed irregularly. The marked protective effect of MP in TBE virus persistence in monkeys is not associated with stimulation of humoral immunity but is mediated by other immunological mechanisms requiring further study.

Tick-borne viral encephalitis in Finland. The clinical features of Kumlinge disease during 1959-1987

During 1959-1987, 126 patients in Aland Islands and main Finland had serologically verified infections with the virus of tick-borne encephalitis (Kumlinge disease). The most useful test for specific virological diagnosis was haemagglutination inhibition-IgM (HI-IgM). Most cases were from Aland Islands and nearby south-western main Finland. Two of the infections were imported. There were three laboratory infections and two transfusion infections. The disease occurred mainly from July to September. Detailed hospital records of 108 of the patients could be obtained. Ninety-five per cent of the patients had headaches, 82% had lymphocytosis of the cerebrospinal fluid, and 81% had high fever. Forty-four per cent had a confirmed biphasic course of disease. Seventeen per cent were severely ill. There were no deaths. The sequels were psychic irritability and fatigue for up to 1 year. There were eight cases of paresis, two of which became permanent.

[Combined antiviral effect of synthetic polyribonucleotide interferonogens and specific antiviral antibodies in arbovirus infections]

A model of tick-borne encephalitis in BALB/c mice was used to investigate the protective anti-viral effect of an interferon inducer, poly(G).poly(C), and specific gamma-globulin administered to the animals together or separately in small doses 24 hours before or after virus inoculation. Administration to the animals of poly(G).poly(C) alone or gamma-globulin alone was shown to produce a poor protective effect. Simultaneous administration of both preparations resulted in a significant decrease of mouse mortality after infection. As a result of the pretreatment of chick embryo cell cultures with poly(G).poly(C) before inoculation and the addition of specific immune serum to the agar overlay after the Sindbis virus inoculation, its multiplication was inhibited much more than after treatment of the cells with interferon inducer alone or antibody alone. Possible mechanisms of the observed additive antiviral effects of the interferon inducer and antibody, including those associated with the influence on the virus-induced interferon production, as well as the possibility of their combined use for the prevention and treatment of viral infections are discussed.

[Combined use of a specific vaccine and interferon inducers for preventing and treating experimental tick-borne encephalitis]

A comparative study of prophylactic and therapeutic activity of 6 Soviet interferon inducers in tick-borne encephalitis was carried out. Such inducers as double-stranded RNA, poly(G) . poly(C), and tyloron were most active prophylactically. A therapeutic effect was observed after combined use of specific vaccine and interferon inducers: double-stranded RNA and poly(G) . poly(C) which underwent clinical trials. When these inducers were administered 3 hours after infection the protective effect was 56.7% and 46%, respectively.

[Donor immunization with an inactivated concentrated purified vaccine against tick-borne encephalitis to obtain immune blood preparations]

Vaccination of seronegative and seropositive donors with a concentrated purified vaccine (CV) against tick-borne encephalitis induced antibody synthesis in a concentration sufficient for preparation of donor immunoglobulin with antibody titres of 1:320 to 1:1280 by HI test. The resulting preparation showed a high antiviral activity both in vivo and in vitro against antigenically different strains of tick-borne encephalitis virus. The immune plasma derived from CV-immunized donors had a therapeutic effect in patients with tick-borne encephalitis. The optimal schedules for immunization of donors are discussed.

[Experimental basis of a protocol for the pathogenetic immunotherapy of tick-borne encephalitis]

In experimental tick-borne encephalitis (TBE) in mice with suppressed immunity, the effectiveness of serotherapy increases markedly. Antibodies prevented the development of persistent infection in the immunosuppressed animals. Antiviral antibodies were shown in vivo to be capable of inhibiting the development of the damaging effect of T-killers immune to the virus. The experimental evidence permits one to formulate the principle of pathogenetic immunotherapy of acute forms of experimental TBE stipulating the use of specific antibodies in the presence of temporary inhibition of the T-cell function.

[Clinical picture of Central European tick-borne encephalitis (author's transl)]

Tick-borne encephalitis is transmitted by the tick ixodes ricinus. After the second world war an increase in the number of cases of encephalitis was observed and the neurotropic virus was isolated for the first time in 1948. Reservoir animals are mouse-like wild animals and also agricultural domestic animals. The infection is transmitted to humans through tick bites. It becomes apparent subjectively in headaches, vomiting, tiredness, giddiness and insomnia, and objectively in meningeal symptoms, extrapyramidal tremor, cerebellar ataxia, vestibular nystagmus and paresis. The treatment consists of strict rest in bed for 10 days at least and symptomatic support of the general health. Good results are obtained with antiedematous therapy with hydrocortisone or pyritinol.

A case of Powassan virus encephalitis

A case of encephalitis due to Powassan virus, probably transmitted through tick-bite, is reported in an 8-year-old boy. There was a 50-fold increase in neutralization titre against Powassan virus, but the virus could not be isolated. Other virological investigations were negative.The patient survived and early physiotherapy and speech re-education could be instituted. Nine months after onset of illness the patient showed moderate sequelae, despite a very severe illness.