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Introduction: Monitoring of meningitis and/or encephalitis regardless of etiology is part of routine epidemiological surveillance in Poland. In this study, we discuss in detail meningitis and/or encephalitis in 2022 caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, and tick-borne encephalitis virus., Objective: The aim of this study was an epidemiological assessment of the occurrence of meningoencephalitis and encephalitis in Poland in 2022, taking into account the analysis of the impact of the COVID-19 pandemic., Material and Methods: To analyze the epidemiological situation of neuroinfections in Poland, we used data sent to NIPH NIH-NRI by the Sanitary and Epidemiological Stations and published in the annual bulletins: "Infectious Diseases and Poisons in Poland in 2022" and "Vaccinations in Poland in 2022" as well as individual epidemiological interviews registered in the EpiBase system., Results: In 2022, a total of 1747 cases of meningitis and/or encephalitis were registered in Poland. This was a 79.4% increase in the number of cases compared to 2021, when 974 cases were recorded. For infections of bacterial etiology, including cases of neuroborreliosis, the number of cases increased by 62.3% . The incidence of meningitis and/or encephalitis of N. meningitidis etiology meningitidis increased by 30.8%, with etiology of H. influenzae compared to 2021 increased by 300%, and for S. pneumoniae by 71.9%. Infections of viral etiology accounted for 52% of all registered cases. There was an increase in their number by 99.1% compared to 2021. Among viral infections, tick-borne encephalitis was the most numerous group, with 466 cases compared to 210 in 2021., Summary and Conclusions: The year 2022 showed an overall upward trend in the number of registered cases of bacterial and viral meningitis and/or encephalitis compared to 2021. Still, the observed number of cases of meningitis and/or encephalitis of both bacterial and viral origin remains below the levels observed in the period before the COVID-19 pandemic.

Introduction: Meningitis meningitis and/or encephalitis regardless of etiology are subject to monitoring in Poland as part of routine epidemiological surveillance. In this paper, meningitis and/or encephalitis in 2021 caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and tick-borne encephalitis virus are discussed in detail. In Poland, immunoprophylaxis in the form of mandatory or recommended vaccinations is used to prevent diseases caused by the aforementioned etiological agents., Aim of the Study: The aim of this study was to assess the epidemiological incidence of meningoencephalitis and encephalitis in Poland, in 2021 including analysis of the impact of the COVID-19 pandemic., Material and Methods: To analyse the epidemiological situation of neuroinfections in Poland, we used data sent to NIPH NIH - NRI by Voivodeship Sanitary and Epidemiological Stations and published in the annual bulletin: "Infectious diseases and poisonings in Poland in 2021" and "Protective vaccination in Poland in 2021" as well as individual epidemiological interviews recorded in the EpiBase system., Results: In 2021, a total of 973 cases of meningitis and/or encephalitis were registered in Poland. This is a 16.1% increase in the number of cases compared to 2020, but still a 57% decrease in the number of cases compared to 2019 when 2,249 cases were recorded. For infections of bacterial etiology, including cases of neuroborreliosis, the number of cases increased by 38.3% (from 376 to 520, incidence from 0.96 to 1.76 per 100,000). Compared to 2020 and 2019, the incidence of meningitis and/or encephalitis of N. meningitidis decreased by 10.7% (from 0.13 to 0.15) and 47.4% (from 0.25 to 0.13), respectively, and for H. influenzae by 75% (from 0.01 to 0.03) and 70% (from 0.01 to 0.03). For S. pneumoniae, we can speak of an increase in incidence against 2020 of 57.1% (121 vs 77 cases, incidence 0.32 vs 0.20) and a decrease against 2019. (121 vs 190, incidence 0.32 vs 0.47). Infections of viral etiology accounted for 47% of all registered cases. There was a slight decrease in their number, by 2% (from 462 to 453 cases). In addition, there was an increase in cases of tick-borne encephalitis, from 158 in 2020 to 210 in 2021 (an increase of 32.9%), and a decrease in cases from 265 in 2019 (a decrease of 20.8%)., Summary and Conclusions: 2021 showed an overall upward trend in the number of recorded cases of bacterial meningitis and/or encephalitis, and a slight decrease in the number of viral meningitis and/or encephalitis cases compared to 2020. Still, the observed number of meningitis and/or encephalitis cases in 2021, both bacterial and viral incidences, remains below the levels observed in the pre-pandemic COVID-19 period (2019). As a result of the SARS-CoV-2 outbreak, the introduction of measures to limit the transmission of the SARS-CoV-2 virus has been observed to reduce the spread of other droplet- and airborne pathogens, thus also pathogens such as S. pneumoniae, H.influenzae and N. menningitidis., (National Institute of Public Health NIH – National Research Institute.)

Introduction: Meningitis and/or encephalitis are one of the main infectious diseases of the nervous system. These diseases are most commonly caused by bacterial and viral etiological factors. In this publication, meningitis and/or encephalitis caused by Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and those with a viral origin - in Poland, most often caused by tick-borne encephalitis virus - are presented in detail. In addition to epidemiological surveillance, immunoprophylaxis in the form of mandatory and recommended vaccinations is used in Poland to prevent these infections., Aim of the Study: The aim of this study was to to assess the epidemiological situation of meningitis and encephalitis in Poland, in 2020., Material and Methods: To analyse the epidemiological situation of neuroinfections in Poland were used data sent to NIPH NIH - NRI by Voivodeship Sanitary and Epidemiological Stations and published in the annual bulletins: "Infectious diseases and poisonings in Poland in 2020" and "Protective vaccination in Poland in 2020" and individual epidemiological interviews registered in the EpiBaza system., Results: In 2020, a total of 831 cases of meningitis and/or encephalitis were registered in Poland. This is a decrease in incidence of up to 62.9% compared to 2019. For infections of bacterial etiology, including cases of neuroborreliosis (incidence of 2.40 per 100,000), the number of cases decreased by 60.4% (from 931 to 369). In the viral infection group, there was a 64.9% decrease (from 1,318 to 462 cases). Of all registered cases, 56% were infections with a viral etiology. Compared to 2019, the number of cases with an S. pneumoniae etiology decreased by 61.3% and for N. meningitidis by 41.1%. It is interesting to note that, in the case of H. influenzae, we can speak of a 20% increase in cases compared to the previous year. In addition, we can see a decrease in the incidence of tick-borne encephalitis - from 265 in 2019 to 158 in 2020 (a decrease of 40.4%)., Summary and Conclusions: Overall, a downward trend in incidence was shown for both bacterial and viral meningitis and/or encephalitis. The SARS-CoV-2 pandemic and the introduction of restrictions on personto-person contact and various forms of activity, resulting in a reduction in pathogen transmission, were key to the significant reduction in the number of meningitis and/or encephalitis cases in 2020, but a reduction in the availability of medical facilities or the completeness of case reports due to the burden of anti-epidemic measures on the Sanitary Inspectorate cannot be excluded either. Only in the case of cases caused by H. influenzae was a slight increase observed compared to the previous year (12 versus 10 cases). Meningoencephalitis and/or encephalitis, due to its wide etiological range, poses a major challenge to the health care system, particularly in terms of correct clinical diagnosis., (© National Institute of Public Health NIH – National Research Institute.)

Introduction: The most common form of infectious diseases of the nervous system is meningitis and encephalitis. This study discusses in detail bacterial meningitis and/or encephalitis in which the etiological factors are: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae and viral - in Poland, most often caused by tick-borne encephalitis virus. In addition to routine epidemiological surveillance of diseases caused by these etiological factors, mandatory and recommended vaccinations are carried out in Poland aimed at reducing the number of cases caused by N. meningitidis, S. pneumoniae, H. influenzae and TBEV., Aim of the Study: The aim of the study is to assess the epidemiological situation of meningitis and encephalitis in Poland in 2019., Material and Methods: The epidemiological situation of meningitis and encephalitis in Poland was assessed on data sent to NIPH NIH - NRI by voivodeship sanitary-epidemiological stations and published in the annual bulletin "Infectious diseases and poisoning in Poland in 2019" and "Vaccinations in Poland in 2019"., Results: In 2019, a total of 2,239 cases of meningitis and encephalitis were registered in Poland. This is a decrease by approximately 19,9% compared to 2018. In the case of bacterial infections, including neuroborreliosis, the number of cases decreased by 27%, from 1265 to 921 cases. In the group of viral infections, a decrease by 14% (from 1,533 to 1,318 cases) was recorded. In 31% of all the cases of bacterial etiology, the etiological factor was one of three: Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae. Infections of viral etiology accounted for 58.9% of all registered cases. Compared to 2018, the number of S. pneumoniae cases decreased by 14.6%, and in the case of N. meningitidis by 6.9%. In the case of H. influenzae, there was an increase in the number of cases, compared to the previous year. In addition, there was a slight increase in the number of cases of tick-borne encephalitis - from 197 cases in 2018 to 265 cases in 2019 (an increase of 34.5%)., Summary and Conclusion: The analysis showed a generally declining disease trend, both in bacterial and viral meningitis and encephalitis. Only in cases caused by H. influenzae and tick-borne encephalitis virus, an increase was observed compared to the previous year. Meningitis and encephalitis continues to be a challenge for the healthcare system, with particular emphasis on the correct differentiation of the etiology at an early stage of infection detection., (© National Institute of Public Health NIH – National Research Institute.)

Introduction: Infectious diseases of the nervous system are most often manifested in the form of meningitis. We distinguish meningitis and/or encephalitis according to their etiology, i.e. bacterial and viral. The study discusses meningitis and encephalitis caused by: N. meningitidis, S. pneumoniae, H. influenzae and tick-borne encephalitis virus. This is due to the epidemiological surveillance of these diseases and the available prevention in the form of vaccinations against these diseases., Aim of the Study: The aim of the study is to assess the epidemiological situation of meningitis and encephalitis in Poland in 2018., Material and Methods: The epidemiological situation of meningitis and encephalitis in Poland was assessed on data from the annual bulletin "Infectious diseases and poisoning in Poland in 2018" and "Vaccinations in Poland in 2018"., Results: In 2018, a total of 2406 cases of meningitis and/or encephalitis were registered in Poland. It is a 14.7% increase in incidence compared to 2017. An increase was recorded in the viral infections from 1212 to 1533 cases. In contrast, the number of infections with bacterial etiology decreased from 886 to 873 cases. Meningitis and/or encephalitis caused by pathogens specified in epidemiological surveillance have noticed a decreased incidence. The only exception is the increase in cases caused by S. pneumoniae, compared to 2017, from 177 to 212. This is an increase of 19.8% compared to the previous year. However, the number of cases of N. meningitidis showed a decrease of 16.4% during this period. Viral infections constituted 63.7% of all cases. Compared to 2017, it means an increase in the percentage of viral infections by 5.9 percentage points. Among laboratory confirmed cases of meningitis and/or encephalitis of known etiology, cases caused by Neisseria meningitidis (102 cases), Streptococcus pneumoniae (212 cases) and tick-borne encephalitis (197 cases) were predominant., Summary and Conclusion: There is a general increasing trend in the number of cases of viral meningitis and/or encephalitis. On the other hand, thanks to vaccinations, no significant increase was noted in H. influenzae, meningococcal and TBE infections. There is a chance to minimize the incidence of bacterial meningitis and/or encephalitis as in the H. influenzae infections. On the other hand, it should be seen that the problem of diagnosing cases of viral etiology should be considered. This is more related to the determination of the etiological factor than the diagnosis of viral meningitis and/or encephalitis. Difficulties in determining the etiological factor indicate that, meningitis and/or encephalitis remain a challenge for healthcare and epidemiological surveillance institutions., (© National Institute of Public Health – National Institute of Hygiene.)

Introduction: Meningitis are the most common form of the nervous system infectious diseases. There are meningitis and/or encephalitis with bacterial and viral etiology. In epidemiological surveillance are highlighted meningitis and/or encephalitis caused by N. meningitidis, S. pneumoniae, H. influenzae and tick-borne encephalitis virus. Because vaccinations against these agents are common., Aim of the Study: The aim of the study is to assess the epidemiological situation of meningitis and encephalitis in Poland in 2017., Material and Methods: The epidemiological situation of meningitis and encephalitis in Poland was assessed on data from the annual bulletin “Infectious diseases and poisoning in Poland in 2017” and “Vaccinations in Poland in 2017”. (MP Czarkowski et al., Warsaw 2018, NIZP-PZH, GIS)., Results: In 2017 were registered 2 095 cases of meningitis and/or encephalitis in Poland. It means a 10.8% decrease in meningitis and/or encephalitis in Poland compared to 2016. With a general decrease in the number of infections of bacterial etiology, the number of cases of meningitis and/or encephalitis of S. pneumoniae, H. influenzae type B cases reported remains at the same level similar to last year. In contrast, the number of cases of etiology of N. meningitidis shows an increase of 25.4% compared to the previous year. Among all cases 57.9% were viral infections. In comparison to 2016 means a decrease in the percentage share of viral infections by 1.2 percentage points for bacterial infections. Among laboratory confirmed cases of neuroinfection with established etiology, the incidence caused by Neisseria miningitidis (122 cases), Streptococcus pneumoniae (171 cases) and tick-borne encephalitis (283 cases) are the most prevalent., Summary and Conclusion: There is a general downward trend in the number of meningitis and/or encephalitis cases, which may be due to introducing mandatory vaccination against S. pneumoniae. It can also mean an improvement in diagnostics given the decrease in unspecified meningitis and/or encephalitis. However meningitis and/or encephalitis remain a challenge for healthcare and epidemiological surveillance institutions., (© National Institute of Public Health – National Institute of Hygiene)

Human pegivirus (HPgV), previously called hepatitis G virus or GB virus C, is a lymphotropic virus with undefined pathology. Because many viruses from the family Flaviviridae, to which HPgV belongs, are neurotropic, we studied whether HPgV could infect the central nervous system. We tested serum and cerebrospinal fluid samples from 96 patients with a diagnosis of encephalitis for a variety of pathogens by molecular methods and serology; we also tested for autoantibodies against neuronal antigens. We found HPgV in serum and cerebrospinal fluid from 3 patients who had encephalitis of unclear origin; that is, all the markers that had been tested were negative. Single-strand confirmation polymorphism and next-generation sequencing analysis revealed differences between the serum and cerebrospinal fluid-derived viral sequences, which is compatible with the presence of a separate HPgV compartment in the central nervous system. It is unclear whether HPgV was directly responsible for encephalitis in these patients.

Aim of the Study: The aim of this study was to assess the epidemiology of meningitis and/or encephalitis in Poland in 2015, Introduction: In the last four years in Poland, about 3 000 cases of meningitis and/or encephalitis of viral or bacterial etiology were recorded annually, Materials and Methods: Assessment of the epidemiological situation of meningitis and/or encephalitis in Poland in 2015, was based on the results of the analysis of epidemiological reports sent to the NIZP-PZH by the Regional Sanitary-Epidemiological Stations published in the annual bulletin “Infectious diseases and poisonings in Poland in 2015” and “Vaccination in Poland in 2015”, Results: In 2015 in Poland 2 428 cases of bacterial meningitis and/or encephalitis were recorded. 43.1% of these were viral infections, Summary and Conclusions: In 2015, in comparison to 2014, a 21.8% decrease in the number of cases of meningitis and/or encephalitis was observed

Aim of the Study: The aim of this study was to assess the epidemiology of meningitis and/or encephalitis in Poland in 2013., Introduction: In the last three years in Poland, about 3000 cases of meningitis and/or encephalitis of viral or bacterial etiology were recorded annually., Materials and Methods: Assessment of the epidemiological situation of meningitis and/or encephalitis in Poland in 2013, was based on the results of the analysis of epidemiological reports sent to the NIZP-PZH by the Regional Sanitary-Epidemiological Stations published in the annual bulletin "Infectious diseases and poisonings in Poland in 2013" and "Preventive immunizations in Poland in 2013"., Results: In 2013 in Poland 3,116 cases of bacterial meningitis and/or encephalitis were recorded. Almost 50% of these were viral infections., Summary and Conclusions: The epidemiological situation of meningitis and/or encephalitis in Poland in 2013 compared to 2012 did not change significantly.

Introduction: About 2 000-3 000 cases of meningitis and/or encephalitis of viral or bacterial etiology are recorded every year in Poland., Aim of the Study: The aim of this study was to assess the epidemiology of meningitis and/or encephalitis in Poland in 2011 and compare it to the situation in previous years., Materials and Methods: Assessment of the epidemiological situation of meningitis and/or encephalitis in Poland in 2011, was based on the results of analysis of epidemiological interviews sent to the NIZP-PZH by the Regional Sanitary-Epidemiological Stations published in the annual bulletin "Infectious diseases and poisonings in Poland in 2011" and "Preventive immunizations in Poland in 2011" (Czarkowski MP. et al., Warsaw, NIZP-PZH, GIS)., Results: In 2011 in Poland it was recorded 2 915 cases of meningitis and/or encephalitis. This included 1 438 cases of viral etiology, 888 of bacterial etiology and 589 of other etiology specified or unspecified. Among the reported cases of bacterial meningitis and/or encephalitis dominant etiological factor was N. meningitidis (193), S. pneumoniae (192) and H. influenzae type B (11). Among the infections of viral etiology predominated was virus of tick-borne encephalitis (221)., Summary and Conclusions: The epidemiological situation of inflammatory meningitis - meningitis and/or brain in Poland in 2011 compared to 2010 did not change significantly.

Introduction: Annually 2 000-3 000 cases of meningitis and encephalitis are notified to the Polish surveillance system. The leading etiologic agents of the bacterial infections are: N. meningitidis, S. pneumoniae, H. influenzae type B and L. monocytogenes. The most common causes of bacterial infections in children are: E. coli, S. agalactiae and H. influenzae type B. The viral infections are mainly caused by the following pathogens: Echovirus, Coxsackie virus group A and B. The agents responsible for the viral infections are also: arboviruses, Herpes simplex virus and mumps virus., Objectives: The objectives of the present article are to analyze the epidemiology of meningitis and encephalitis in Poland in 2010 and to present the information on the vaccines used to prevent the discussed infections., Material and Methods: The analysis was based on the data retrieved from the questionnaires used for the surveillance purposes, aggregated data on meningitis and encephalitis published in "Infectious diseases and poisonings in Poland in 2010", aggregated data on the vaccination coverage published in "Vaccinations in Poland in 2010", "Case definitions for the infectious diseases used for the surveillance purposes in 2009-2011" and Polish Immunization Programme for 2010., Results: In 2010, Poland reported 3 063 neuroinfections--nearly 22% more than in 2009. The incidence rate was 8.03 cases per 100 000 population. From the analysis of data transpired that of the notified cases, 1 619 were of viral etiology, 846--were bacterial and 598 of other or unknown origin. Given the bacterial infections of determined etiology, the leading pathogenic agent was S. pneumoniae (180 cases), following by N. meningitidis (146 cases) and Haemophilus influenzae typu B (11 cases). Among confirmed cases of the viral infections, the predominant were tick-borne encephalitis cases (294)., Conclusions: Compared to the data from 2009, the epidemiologic situation of the meningitis and encephalitis in Poland in 2010 has not changed significantly.

In Poland, 2 517 cases of neuroinfections were reported in 2009, of which 865 had bacterial aetiology, 1 244--viral aetiology, and 408-- other or unknown origin. The etiological agent was determined in 493 (57%) cases of bacterial neuroinfections. Among them Neisseria meningitidis was found in 190 cases, Haemophilus influenzae type B (Hib) in 13 cases and Streptococcus pneumoniae in 163 cases. An increasing trend in pneumococcal infections incidence has been observed since 2005, and a substantial decrease of Hib incidence, related to increasing vaccination coverage. Viral neuroinfections incidence in 2009 increased compared to year 2008. Among confirmed cases, there were 351 cases of tick-borne encephalitis. Most of the cases were reported from endemic areas of north-eastern part of the country.

In Poland, 2 475 cases of neuroinfections were reported in 2008, of which 979 had bacterial aetiology, 1 122--viral aetiology, and 374--other or unknown origin. The etiological agent was determined in 555 (56%) cases of bacterial neuroinfections. Among them Neisseria meningitidis was found in 220 cases, Haemophilus influenzae type B (Hib) in 23 cases and Streptococcus pneumoniae in 151 cases. An increasing trend in meningococcal infections incidence has been observed in 2008, and a substantial decrease of Hib incidence, related to increasing vaccination coverage. Viral neuroinfections incidence in 2008 decreased compared to year 2007. Among confirmed cases, there were 202 cases of tick-borne encephalitis. Most of the cases were reported from endemic areas of north-eastern part of the country.

Background and Purpose: Bickerstaff's brainstem encephalitis (BBE) is a very uncommon central nervous system disease. Its etiology remains unknown but it is postulated that BBE has an autoimmunologic origin. BBE is characterized by acute ophtalmoplegia, ataxia, pyramidal paresis and disturbance of consciousness. A special pattern of changes in magnetic resonance imaging (MRI) is characteristic of BBE. Lesions are located mainly in the brainstem. The aim of this paper is to analyze the clinical course and MRI changes in our own cases of BBE., Material and Methods: We have analyzed medical records, clinical findings and MRI images of the patients with BBE diagnosis established in our Department of Neurology in the years 1998-2004., Results: During that period 4 cases of BBE were diagnosed with clinical sings of acute brainstem lesion and MRI imaging suggestive of BBE. In our patients we have observed ophtalmoplegia, ataxia, disturbances of consciousness and pyramidal signs. Two patients had a monophasic and 2 remitting-relapsing course of the disease. In all four cases we have seen on T2-weighted images large, irregular hyperintense lesions in the brainstem, especially in the pons, midbrain and medulla, but also in one case in the thalamus and vermis of the cerebellum. Patients were treated with steroids, plasmapheresis or acyclovir or a combination of these methods. We observed a complete recovery in two cases and significant improvement in the other two lasting more than two years confirming a relatively good prognosis in BBE., Conclusions: BBE despite severe initial presentation usually has a good prognosis. MRI plays critical role in the diagnosis of BBE.

In Poland, 2 725 cases of neuroinfections were reported in 2004, of which 945 had bacterial etiology, 1427 viral, and 353 cases had other or unknown origin. Incidence of bacterial neuroinfections increased in 2004, despite a decreasing trend observed during the past decade. Etiological factor was determined in 433 (46%) cases of bacterial neuroinfections. Among them Neisseria meningitidis was found in 119 cases, Haemophilus influenzae in 77 cases and Streptococcus pneumoniae in 107 cases. As in the previous years, serotype B was the predominant type of N. meningitidis cultured from patients, but type C appears to be systematically increasing, accounting for 27% of the strains serotyped in 2004. Viral neuroinfections were less common in 2004, compared to previous years. Etiological factor of central nervous system aseptic infections were established only in 17% of cases. Among confirmed cases, there were 262 cases of tick-borne encephalitis and 15 cases of herpetic encephalitis. Tick borne encephalitis incidence decreased in 2004 (0.7), compared to 2003 (339 cases, incidence 0.9). Most of the cases were reported from endemic areas of north-eastern part of the country.

In Poland, 829 cases of bacterial meningitis and encephalitis, 563 cases of viral encephalitis, 973 of viral meningitis and 300 cases of meningitis and encephalitis of other or unknown etiology were reported in 2003. Incidence of the bacterial central nervous system infections has been declining over the past decade and the level of viral infections other then tick-borne encephalitis, following the outbreak in the mid-nineties, remained stable. Etiological factor was determined in 352 (42%) cases of bacterial meningitis/encephalitis. Among them Neisseria meningitidis was found in 76 cases, Haemophilus influenzae in 68 cases and Streptococcus pneumoniae in 91 cases. As in the past type B was the predominant type of N. meningitidis cultured from the patients, but type C appears to be on the rise accounting for 36% of the strains serotyped in 2003. Tick borne encephalitis increased markedly in 2003, with the highest ever noted number of cases (339). Most of the cases were reported from endemic areas of north-eastern part of the country.

In Poland, 861 cases of bacterial meningitis and encephalitis, 307 cases of viral encephalitis, 1022 of viral meningitis and 286 cases of meningitis and encephalitis of other or unknown etiology were reported in 2002. Incidence of the bacterial central nervous system infections has been declining over the past decade and the level of viral infections, following the outbreak in the mid-nineties, remained stable. Etiological factor was determined in 365 (42%) cases of bacterial meningitis/encephalitis. Among them Neisseria meningitidis was found in 90 cases, Haemophilus influenzae in 72 cases and Streptococcus pneumoniae in 85 cases. As in the past type B was the predominant type of N. meningitidis cultured from the patients, but type C appears to be on the rise accounting for 35% of the serotyped strains. 126 cases of tick borne encephalitis were reported in Poland in 2002, most of them from endemic areas of north-eastern part of the country.

2367 cases of meningitis and 571 of encephalitis were reported in Poland in 2001. Among meningitis 1324 cases were classified as viral and 838 as bacterial. Among encephalitis cases, 117 were classified as bacterial and 383 as viral. Etiological factor was determined in 419 (44%) cases of bacterial meningitis/encephalitis. Among them Neisseria meningitidis was found in 106 cases, Haemophilus influenzae in 75 cases and Streptococcus pneumoniae in 99 cases. As in the past type B was the predominant type of N. meningitidis cultured from patients. 210 cases of tick borne encephalitis were reported in Poland in 2001, most of them from endemic areas of north-eastern part of the country.

A total of 2,033 cases of meningitis and 570 of encephalitis were reported in Poland in 2000. Among cases of meningitis 1,051 (51.7%) were classified as viral and 982 (48.3%) as bacterial. Etiological factors were determined in 36.7% (360/982) cases of bacterial meningitis. Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae were found in 10.3% (101/982), 8.7% (85/982), and 7.5% (74/982) cases, respectively. As in previous years, N. meningitidis typed B was strongly predominating. Out of 570 cases of encephalitis, 170 (29.8%) were tick borne, of which most were reported from endemic areas of north-eastern part of the country.

2,020 cases of meningitis and 494 of encephalitis were reported in Poland in 1999. Among meningitis 1,024 cases were classified as viral and 996 as bacterial. Etiological factor was determined in 264 (26.5%) cases of bacterial meningitis. Among them Neisseria meningitidis was found in 119 cases, Haemophilus influenzae in 63 cases and Streptococcus pneumoniae in 90 cases. Among types of diagnosed N. meningitidis, as in previous years, type B was strongly predominating. Out of 494 cases of encephalitis 101 cases of tick borne encephalitis were reported in Poland in 1999, most of them from endemic areas of north-eastern part of the country.

In 1998--3,024 cases of meningitis and 581 cases of encephalitis were reported. It was 1,436 cases less then in 1997. A significant decrease of enteroviral meningitidis was observed and strains of ECHO30 was not dominant, it was Cox B5. Among bacterial factors the most common was N. meningitidis. 131 sporadic cases of meningitis caused by this bacteria were reported with serotype B dominating (96%). There were 103 cases of bacterial meningitis caused by S. pneumoniae and 101 cases caused by H. influenzae b among those with confirmed diagnosis. There were 208 cases of tick-borne encephalitis, diagnosed mainly in endemic areas of Białystok and Suwałki voivodeships.

In 1997, 4,409 cases of meningitis and 632 cases of encephalitis were reported in Poland. Meningitis incidence rate was 11.4 per 100,000, and was 3-times lower than in 1996. The etiology of meningitis cases was as follows: 2,713 (61.5%) were due to viral agents (ECHO 30 dominated), 1,351 (30.7%) were caused by bacterial agents: 144 meningococcal (3.3%) and 1,207 other bacterial. The bacterial etiology was following: 33.2% were due to Streptococcus pneumoniae, 27.6% were cased by Haemophilus influenzae type b, and 11.6% by Staphylococci. Encephalitis incidence rate was 1.6 per 100,000. There were 201 cases of tick-borne encephalitis, found mainly in endemic areas of Białystok and Suwałki voivodeships.

Clinical course of Herpes Simplex Encephalitis were shown in this paper. 24 children in the age of 4 to 15 were treated at Polish Mother's Memorial Hospital in years 1992-1994. Value of EEG, CT scan, NMR were underlined in early diagnostic and casual treatment of diseases. All children from this analysis group survived, only 8 demonstrated late complications: epileptic attacks (3), spastic tetraparesis (1), encephalopathy and mental disturbances (1). Positive results of treatment were connected with early diagnosis and early antiviral treatment which is very important in decreasing death rate and preventing permanent injury.

From 1983 to 1990, at the I Clinic of Infectious Diseases, Silesian Academy of Medicine in Bytom, 995 patients with meningitis and encephalitis were treated; the average age was 17.86 years. After cerebrospinal fluid (CSF) examinations the patients were divided into groups. The first group consisted of patients with suppurative meningitis and encephalitis (202-20.30%), the other group were patients with aseptic meningitis (309-31.06%), a separate group consisted of patients with mumps meningitis (484-48.06% cases). In the group with suppurative meningitis and encephalitis etiological agents were isolated (Gram stain smear and/or culture of CSF) in 50.99% of cases. The most common causes of suppurative neuroinfections were: Neisseria meningitides and Streptococcus pneumoniae (in 23.76% cases). The increasing number of bacteriological tests positive results was observed during the analyzed period. The etiology of aseptic inflammation diseases of the central nervous system was defined with the help of serologic blood tests in 10-15%, and serologic confirmation of mumps meningitis was as high as 80% of cases. In the group of purulent neuroinfections, during the 8-year observation, 36 deaths occurred (17.82% of these patients). The observed tendency of the death rate decrease is concerned to be a result of better microbiological diagnostics and the possibility of an early aimed antibiotic therapy.