Increased Relative Risk of Tick-Borne Encephalitis in Warmer Weather.

Tick-borne encephalitis (TBE) is a serious acute neuroinfection of humans caused by a tick-borne flavivirus. The disease is typically seasonal, linked to the host-seeking activity of Ixodes ricinus (predominantly nymphs), the principal European tick vector species. To address the need for accurate risk predictions of contracting TBE, data on 4,044 TBE cases reported in the Czech Republic during 2001-2006 were compared with questing activity of I. ricinus nymphs monitored weekly at a defined location for the same 6-year period. A time shift of 21 days between infected tick bite and recorded disease onset provided the optimal model for comparing the number of cases of TBE with numbers of questing nymphs. Mean annual distribution of TBE cases and tick counts showed a similar bimodal distribution. Significantly, the ratio of TBE cases to questing nymphs was highest in the summer-autumn period even though the number of questing nymphs peaked in the spring-summer period. However, this pattern changed during a period of extreme meteorological events of flooding and abnormally high temperatures, indicating that changes in climate affect the incidence of TBE. Previous studies failed to link human behavior with changes in incidence of TBE but showed extrinsic temperature impacts arbovirus replication. Hence, we hypothesize the apparent discrepancy between peak nymphal tick activity and greatest risk of contracting TBE is due to the effect of temperature on virus replication in the tick vector. Relative proportions of questing nymphs and the numbers of weeks in which they were found were greater in summer-autumn compared with spring-summer at near-ground temperatures >5°C and at standard day and weekly average temperatures of >15°C. Thus, during the summer-autumn period, the virus dose in infected tick bites is likely greater owing to increased virus replication at higher microclimatic temperatures, consequently increasing the relative risk of contracting TBE per summer-autumn tick bite. The data support the use of weather-based forecasts of tick attack risk (based on daytime ambient temperature) supplemented with weekly average temperature (as a proxy for virus replication) to provide much-needed real-time forecasts of TBE risk.

A serological study of antibodies to Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in the sera of healthy individuals collected two decades apart.

Sera collected from healthy individuals from the general population in the Czech Republic during repeated cross-sectional surveys were analyzed. Samples collected in the same six districts in two time periods, 1978-1989 and 2001, were compared. The study subjects were divided into six age categories between 10 and 59 years. Overall, 434 samples from 1978-1989 and 270 samples from 2001 were screened for Anaplasma phagocytophilum (AP) and Borrelia burgdorferi sensu lato (BB). The anti-AP positivity rates were 13.1% and 11.5% in the first and second period, respectively, and did not differ significantly between the periods (P = 0.559). The anti-BB antibodies were detected in 33.9% and 14.8% of study subjects, respectively. The positivity rates were significantly lower in the second period (P<0.001). No considerable changes were observed in the sex distribution of positive findings between the two periods. The highest positivity rates of anti-AP antibodies were found in the 10-14 year age group: 16.0% in 1978-1989 and 16.7% in 2001. The age distribution of the anti-AP antibody positivity rates did not change substantially (P = 0.872). In 1978-1989, the lowest anti-BB antibody positivity rate (26.7%) was found in the 10-14 year age group, with a gradual increase with age to 41.1% in 50-59 year-olds. In 2001, the positivity rate in the 10-14 year age group was 26.2% and was not significantly different from that in the first period (P = 0.955). However, the positivity rates in the older age groups 15-59 years decreased significantly (P<0.001) and varied between 8.3% and 15.1%.

Abiotic predictors and annual seasonal dynamics of Ixodes ricinus, the major disease vector of Central Europe.

BACKGROUND: Abiotic conditions provide cues that drive tick questing activity. Defining these cues is critical in predicting biting risk, and in forecasting climate change impacts on tick populations. This is particularly important for Ixodes ricinus nymphs, the vector of numerous pathogens affecting humans. METHODS: A 6-year study of the questing activity of I. ricinus was conducted in Central Bohemia, Czech Republic, from 2001 to 2006. Tick numbers were determined by weekly flagging the vegetation in a defined 600 m(2) field site. After capture, ticks were released back to where they were found. Concurrent temperature data and relative humidity were collected in the microhabitat and at a nearby meteorological station. Data were analysed by regression methods. RESULTS: During 208 monitoring visits, a total of 21,623 ticks were recorded. Larvae, nymphs, and adults showed typical bimodal questing activity curves with major spring peaks and minor late summer or autumn peaks (mid-summer for males). Questing activity of nymphs and adults began with ~12 h of daylight and ceased at ~9 h daylight, at limiting temperatures close to freezing (in early spring and late autumn); questing occurred during ~70 % calendar year without cessation in summer. The co-occurrence of larvae and nymphs varied annually, ranging from 31 to 80 % of monitoring visits, and depended on the questing activity of larvae. Near-ground temperature, day length, and relative air humidity were all significant predictors of nymphal activity. For 70 % of records, near-ground temperatures measured in the microhabitat were 4-5 °C lower than those recorded by the nearby meteorological observatory, although they were strongly dependent. Inter-annual differences in seasonal numbers of nymphs reflected extreme weather events. CONCLUSIONS: Weather predictions (particularly for temperature) combined with daylight length, are good predictors of the initiation and cessation of I. ricinus nymph questing activity, and hence of the risk period to humans, in Central Europe. Co-occurrence data for larvae and nymphs support the notion of intrastadial rather than interstadial co-feeding pathogen transmission. Annual questing tick numbers recover quickly from the impact of extreme weather events.

Results of the Screening of Tick-Borne Encephalitis Virus Antibodies in Human Sera from Eight Districts Collected Two Decades Apart.

The sera from healthy individuals aged 10-59 years randomly selected from the general population during repeated cross-sectional surveys were stored at -20°C at the serum bank of the National Institute of Public Health in Prague. The sera included in the present study were collected in the 1980s and in 2001 in eight districts of the Czech Republic. The proportional representation of the study localities was similar in both periods. The sera were uniformly distributed in 5-year age groups for 10- to 19-year-olds and in 10-year age groups for 20- to 59-year-olds. Males and females were nearly equally represented in both periods. Altogether 704 sera, 434 from the period 1978-1989 and 270 from 2001, were screened for antibodies against tick-borne encephalitis virus (TBEV) by the virus neutralization test. The seroprevalence rates were 11.5% in the 1980s and 26.3% in 2001. From the logistic regression model, it follows that the chance of detecting anti-TBEV antibodies was more than twice higher in 2001 than in 1978-1989 (odds ratio [OR]=2.22). The differences between males and females were not statistically significant, nor was sex-period interaction. The time trends in the seropositivity rates were similar in all age groups, with the exception of the 10- to 14-year-olds (p=0.914). The rate of seropositives in the age group 15-59 years increased 1.9 times, whereas that in the age group 10-14 years rose 5.1 times. In areas comparable to those where the study sera were collected, the average incidence rates of tick-borne encephalitis (TBE) per 100,000 population aged 10-59 increased significantly from 3.35 in 1978-1989 to 8.96 in 2001 (p<0.001). The age-specific antibody trends in adult age groups in both periods suggest that clinically manifest or inapparent TBE cases do not induce lifelong immunity, but they are likely to reflect the previous epidemiological situation.

Contrasting patterns of hot spell effects on morbidity and mortality for cardiovascular diseases in the Czech Republic, 1994-2009.

The study examines effects of hot spells on cardiovascular disease (CVD) morbidity and mortality in the population of the Czech Republic, with emphasis on differences between ischaemic heart disease (IHD) and cerebrovascular disease (CD) and between morbidity and mortality. Daily data on CVD morbidity (hospital admissions) and mortality over 1994-2009 were obtained from national hospitalization and mortality registers and standardized to account for long-term changes as well as seasonal and weekly cycles. Hot spells were defined as periods of at least two consecutive days with average daily air temperature anomalies above the 95% quantile during June to August. Relative deviations of mortality and morbidity from the baseline were evaluated. Hot spells were associated with excess mortality for all examined cardiovascular causes (CVD, IHD and CD). The increases were more pronounced for CD than IHD mortality in most population groups, mainly in males. In the younger population (0-64 years), however, significant excess mortality was observed for IHD while there was no excess mortality for CD. A short-term displacement effect was found to be much larger for mortality due to CD than IHD. Excess CVD mortality was not accompanied by increases in hospital admissions and below-expected-levels of morbidity prevailed during hot spells, particularly for IHD in the elderly. This suggests that out-of-hospital deaths represent a major part of excess CVD mortality during heat and that for in-hospital excess deaths CVD is a masked comorbid condition rather than the primary diagnosis responsible for hospitalization.

The role of game (wild boar and roe deer) in the spread of tick-borne encephalitis in the Czech Republic.

In the Czech Republic, the incidence of human tick-borne encephalitis (TBE) has been increasing over the last two decades. At the same time, populations of game have also shown an upward trend. In this country, the ungulate game is the main host group of hosts for Ixodes ricinus female ticks. This study examined the potential contribution of two most widespread game species (roe deer [Capreolus capreolus] and wild boar [Sus scrofa]) to the high incidence of TBE in the Czech Republic, using the annual numbers of culls as a proxy for the game population. This was an ecological study, with annual figures for geographical areas-municipalities with extended competence (MEC)-used as units of analysis. Between 2003 and 2011, a total of 6213 TBE cases were reported, and 1062,308 roe deer and 989,222 wild boars were culled; the culls of roe deer did not demonstrate a clear temporal trend, but wild boar culls almost doubled (from 77,269 to 143,378 per year). Statistical analyses revealed a positive association between TBE incidence rate and the relative number of culled wild boars. In multivariate analyses, a change in the numbers of culled wild boars between the 25th and 75th percentile was associated with TBE incidence rate ratio of 1.23 (95% confidence interval 1.07-1.41, p=0.003). By contrast, the association of TBE with culled roe deer was not statistically significant (p=0.481). The results suggest that the size of the wild boar population may have contributed to the current high levels and the rising trend in incidence of TBE, whereas the regulated population of roe deer does not seem to be implicated in recent geographical or temporal variations in TBE in the Czech Republic.

[Incidence of tick-borne encephalitis in the czech republic in 2001-2011 in different administrative regions and municipalities with extended power]. / Incidence onemocnení klístovou encefalitidou v Ceské republice v letech 2001-2011 v jednotlivých krajích a obcích s rozsírenou pusobností

AIM: Analysis of the incidence of tick-borne encephalitis (TBE) in the Czech Republic (CR) in 2001-2011 in different administrative regions and municipalities with extended power (MEPs). MATERIAL AND METHODS: Each TBE case reported to the EPIDAT system was matched to the respective MEP or Prague according to the place of residence. The annual TBE incidence was calculated per 100 000 permanent residents (mean) of each administrative region and MEP. The overall incidence, age-specific incidence, and average incidence by administrative region per year and per the eleven-year period were calculated. RESULTS: In the study period, the highest TBE incidence rates were found in the Plzen Region, South Bohemian Region, and Highlands Region, neighbouring with Germany and Austria. The overall TBE incidence in the CR had a slightly upward trend resulting from different subtrends in various administrative regions. The overall trend was most influenced by the most affected regions with opposite trends - the Highlands Region and the South Bohemian Region. The South Bohemian Region with the highest average incidence in the study period of 23.4/100 000 population also showed the maximum effect on the country-wide age-specific incidence due to the trend in the age--specific incidence, sharply rising to peak in the age group 60-64. As it had long been the region with the highest incidence in the Czech Republic, vaccination campaigns were organized repeatedly there, targeting high-risk areas and children. The vaccine coverage rate in school-age children in the last decade was about 50%. The analysis of age group trends showed no considerable increase in 0-14-year-olds in 2011, i.e. the year with the second highest TBE incidence ever reported in the CR, in contrast to 15 to 44-year-olds where the TBE incidence rates were three times as high. From this it can be inferred that the post-vaccination antibody level and its protective effect wane over years unless a booster dose is given. The incidence trend for TBE in 45-64-year-olds, i.e. the age group who lived life long inside or close to the most active TBE foci, suggests that the contact with the TBE virus does not induce protective herd immunity. The analysis of TBE incidence in the population of smaller administrative areas provides more detailed information. In six MEPs, the average TBE incidence over the 11-year period was more than 30/100 000, with a peak of 58/100 000. CONCLUSION: Although the most important epidemiological information for a disease with natural focality is the place of acquisition of infection, the long-term evaluation of TBE incidence according to the patients place of residence is also relevant. The data on TBE incidence in the population of 205 MEPs provide helpful information for campaigns to reduce the risk of TBE infection targeted to human behaviour in TBE natural foci and preventive measures, particularly vaccination. It cannot be excluded that residents of high-risk areas will continue risky behaviour even in the future.

Trends in cardiovascular mortality and hospitalisations, and potential contribution of inhospital case-fatality rates to changes in national mortality in the Czech Republic 1994-2009.

OBJECTIVES: To analyse trends in cardiovascular disease (CVD) mortality and hospitalisations in the Czech Republic in 1994-2009 and to assess the contribution of inhospital case-fatality rates (CFR) to changes in national CVD mortality. DESIGN: National hospitalisation and mortality registers were used to estimate rates of hospital admissions and mortality for hypertension, angina pectoris, acute myocardial infarction (AMI), chronic ischaemic heart disease chronic (IHD), heart failure and stroke. PATIENTS: All hospitalisations and deaths from CVD during 1994-2009. MAIN OUTCOME MEASURES: Average annual relative changes in age-standardised mortality, hospital admission and inhospital CFR. RESULTS: Between 1994 and 2009, 5 409 407 hospital admissions and 930 659 deaths from CVD were recorded. The age-standardised CVD mortality rate fell from 561 to 357 per 100 000 population (mean annual decline 3.1%) but hospitalisation rates remained relatively stable, with 2800 admissions per 100 000 per year (annual decline 0.7%). Inhospital CFR decreased significantly in all examined diagnoses but most rapidly for AMI (by 5.5% per year) and stroke (4.2% per year). The improvements were larger in the younger population than in elderly persons. Calculations based on unlinked mortality and hospitalisation data suggest that a decline in inhospital CFR may explain approximately 24%, 41% and 61% of the decline in national deaths from IHD, AMI and stroke, respectively. CONCLUSIONS: During the study period, the overall CVD hospitalisation rates remained high but inhospital CFR declined considerably. The improved case-fatality seems to have made a substantial contribution to the decline in the national CVD mortality, particularly for AMI and stroke.

Vaccination and tick-borne encephalitis, central Europe.

Tick-borne encephalitis (TBE) is a substantial public health problem in many parts of Europe and Asia. To assess the effect of increasing TBE vaccination coverage in Austria, we compared incidence rates over 40 years for highly TBE-endemic countries of central Europe (Czech Republic, Slovenia, and Austria). For all 3 countries we found extensive annual and longer range fluctuations and shifts in distribution of patient ages, suggesting major variations in the complex interplay of factors influencing risk for exposure to TBE virus. The most distinctive effect was found for Austria, where mass vaccination decreased incidence to ≈16% of that of the prevaccination era. Incidence rates remained high for the nonvaccinated population. The vaccine was effective for persons in all age groups. During 2000-2011 in Austria, ≈4,000 cases of TBE were prevented by vaccination.

Epidemiology of tick-borne encephalitis in the Czech Republic 1970-2008.

This article presents major epidemiologic features of tick-borne encephalitis (TBE) in the Czech Republic, using data of laboratory-confirmed cases since 1970. A total of 17,053 cases of TBE were reported in the Czech Republic (population 10 million) in 1970-2008. The data show several important features. First, the pattern of TBE incidence changed over time. Until the end of the 1970s, TBE was characterized by periods of alternately higher and lower incidence (between 180 and 595 cases per year); the 1980s were a period of low incidence with minimum variability; since the beginning of the 1990 s, there has been a steep rise in incidence, with marked year-to-year variation (e.g., 745 cases were registered in 1995, and a maximum of 1029 cases were registered in 2006). Second, the age distribution of TBE incidence has changed. Until the end of 1990 s, incidence peaked among those 15-19 years of age, with a gradual decline with age. In the 2000s, however, TBE incidence has been rising in those aged 60-64 years, with a sharp decline in those older than 65 years. Third, the seasonal pattern of TBE has changed markedly over time. In the earlier period, incidence had a clear peak in July/August; since the 1990 s, more cases have occurred in earlier and later months of the year. The proportion of cases occurring in April, May, October, and November increased from 9% in the 1970s to 23% in 2000-2008. Fourth, the geographical distribution of TBE also changed over time, with TBE increasingly occurring in the mountainous districts at higher altitudes. These changes in incidence patterns appear to be linked with changes in climatic and meteorological conditions. The link between climate change and TBE incidence is plausible, since TBE is a recreation-related infection associated with outdoor activities, and since climatic changes affect the life cycle of the vector.

Serologic survey of humans for flavivirus West Nile in Southern Moravia (Czech Republic).

A serosurvey for West Nile virus (WNV) was carried out in 525 persons, using a plaque-reduction neutralization microtest (PRNmicroT) with Vero cells and Egyptian topotype Eg-101 strain as test virus. The blood sera were collected in four South-Moravian districts (Hodonin 44 persons, Breclav 102 persons, Znojmo 170 persons, Jihlava 209 persons) of the Czech Republic in the years 1988 and 1989, and stored at -20 degrees C. Antibodies to WNV were detected in only three humans (0.6% seropositivity): one person each in the districts of Hodonin (2.3% persons positive), Breclav (1.0% positive) and Jihlava (0.5% positive), with the titres of 1:64, 1:32, and 1:32, respectively. All the three sera were negative for antibody to tick-borne encephalitis virus. The results indicate that activity of WNV in southern Moravia was very low before 1990.

Characterization of a natural focus of Puumala hantavirus infection in the Czech Republic.

Hantaviruses are RNA viruses of the Bunyaviridae family, represented in the Czech Republic by three genospecies: Dobrava-Belgrade, Puumala and Tula. They persist in natural foci of infection. In 2004 to 2009, a local outbreak with 18 reported cases of nephropathia epidemica caused by Puumala hantavirus occurred in the Sumava mountains and foothills and was spacially associated with another outbreak in Lower Bavaria, Germany. In the Jeleni locality in the Sumava mountains at 880 m above sea level, we identified a natural focus of infection suspected to be the source of hantavirus infection in forest workers. The focus was characterized geobotanically as a montane mixed forest with the predominance of beeches within the association Dentario enneaphylli-Fagetum, alliance Fagion, sub-alliance Eu-Fagenion, in a cold climate region with a podzolic soil. The biocenoses where hantaviruses are circulating typically show higher microclimate humidity. Their characteristization can be helpful in predicting where hantaviruses are likely to circulate.

The TICKPRO computer program for predicting Ixodes ricinus host-seeking activity and the warning system published on websites.

The computer program with the acronym TICKPRO (tick prognosis) facilitates medium-range forecasts of the level of host-seeking activity in ticks within a 1-4 day horizon. The program is based on the medium-range weather forecast routinely produced at the Czech Hydrometeorological Institute (CHMI), as well as on previously developed mathematical models describing the correlation of meteorological factors with the host-seeking activity of Ixodes ricinus. These models are based on a 6-year whole-season monitoring of I. ricinus host-seeking activity on experimental fields in the Central Bohemia Region in a typical habitat, oakhornbeam forest, where tick-borne encephalitis (TBE) virus and Borrelia burgdorferi s.str., B. afzelii, and B. garinii have been found. Meteorological data provided by the CHMI meteorological station in Prague-Libus were used, and during the development of the forecasting algorithm micrometeorological data have been collected directly at the tick monitoring sites under selected synoptic weather situations. In the TICKPRO program, the two most successful models utilized ambient air temperature, quantity of atmospheric precipitation, and relative air humidity. The prediction determines 5 levels of risk of attack according to the current proportion of host-seeking ticks, and thus determines the risk of TBE infection. The levels of risk defined by the TICKPRO program are supplemented by instructions on how to prepare oneself for entering sites with potential tick occurrence, how to move around once there, and how to behave on returning home. This warning system is weekly published on websites of National Institute of Public Health and CHMI, Prague, over entire season (March-November).

Excess cardiovascular mortality associated with cold spells in the Czech Republic.

BACKGROUND: The association between cardiovascular mortality and winter cold spells was evaluated in the population of the Czech Republic over 21-yr period 1986-2006. No comprehensive study on cold-related mortality in central Europe has been carried out despite the fact that cold air invasions are more frequent and severe in this region than in western and southern Europe. METHODS: Cold spells were defined as periods of days on which air temperature does not exceed -3.5 degrees C. Days on which mortality was affected by epidemics of influenza/acute respiratory infections were identified and omitted from the analysis. Excess cardiovascular mortality was determined after the long-term changes and the seasonal cycle in mortality had been removed. Excess mortality during and after cold spells was examined in individual age groups and genders. RESULTS: Cold spells were associated with positive mean excess cardiovascular mortality in all age groups (25-59, 60-69, 70-79 and 80+ years) and in both men and women. The relative mortality effects were most pronounced and most direct in middle-aged men (25-59 years), which contrasts with majority of studies on cold-related mortality in other regions. The estimated excess mortality during the severe cold spells in January 1987 (+274 cardiovascular deaths) is comparable to that attributed to the most severe heat wave in this region in 1994. CONCLUSION: The results show that cold stress has a considerable impact on mortality in central Europe, representing a public health threat of an importance similar to heat waves. The elevated mortality risks in men aged 25-59 years may be related to occupational exposure of large numbers of men working outdoors in winter. Early warnings and preventive measures based on weather forecast and targeted on the susceptible parts of the population may help mitigate the effects of cold spells and save lives.

Decreased impacts of the 2003 heat waves on mortality in the Czech Republic: an improved response?

The paper examines impacts on mortality of heat waves in 2003, the hottest summer on record in the Czech Republic, and compares them with previous similar events. While most summer heat waves over the period since 1986 were associated with significantly elevated mortality, this was not the case for three out of the four heat waves in 2003. The relatively weak mortality response was particularly noteworthy for the most severe heat wave which occurred in the first 10 days of August 2003 and resulted in enormous excess mortality in some western European countries. A mortality displacement effect and short-term adaptation to heat contributed to the reduced mortality impacts of the heat waves that followed after previous relatively warm periods. However, the decreased mortality response of the 2003 heat waves compared to previous heat waves in the 1990s is also likely to have arisen from positive health-care and other socio-economic changes in the post-communist central European region over the past decade, as well as a better public awareness of heat-related risks due to enhanced media coverage and regular biometeorological forecast and warnings.

Comparison of rubella seroepidemiology in 17 countries: progress towards international disease control targets.

OBJECTIVE: To standardize serological surveillance to compare rubella susceptibility in Australia and 16 European countries, and measure progress towards international disease-control targets. METHODS: Between 1996 and 2004, representative serum banks were established in 17 countries by collecting residual sera or community sampling. Serum banks were tested in each country and assay results were standardized. With a questionnaire, we collected information on current and past rubella vaccination programmes in each country. The percentage of seronegative (< 4 IU/ml) children (2-14 years of age) was used to evaluate rubella susceptibility, and countries were classified by seronegativity as group I (< 5%), group II (5-10%) or group III (> 10%). The proportion of women of childbearing age without rubella protection (< or = 10 IU/ml) was calculated and compared with WHO targets of < 5%. FINDINGS: Only Romania had no rubella immunization programme at the time of the survey; the remaining countries had a two-dose childhood schedule using the measles, mumps and rubella (MMR) vaccine. The percentage of susceptible children defined five countries as group I, seven as group II and four as group III. Women of childbearing age without rubella protection were < 5% in only five countries. CONCLUSION: Despite the low reported incidence in many countries, strengthening the coverage of the routine two-dose of MMR vaccine among children is needed, especially in group III countries. Catch-up campaigns in older age groups and selective targeting of older females are needed in many countries to ensure necessary levels of protective immunity among women of childbearing age.

Risk assessment and prediction of Ixodes ricinus tick questing activity and human tick-borne encephalitis infection in space and time in the Czech Republic.

Present risk assessment and prediction of future risk of humans exposed to Ixodes (I.) ricinus tick attacks and, consequently, to tick-borne encephalitis (TBE) virus infection as one of the basic preconditions for successful TBE prevention has been intensively studied in the Czech Republic. An atlas of TBE in the Czech Republic containing predictive maps of I. ricinus high-incidence habitats and TBE risk sites identified by satellite data (Landsat 5 TM with spatial resolution 30 m) at a scale of 1:200,000 over a territory of 52,000 km(2) and maps of human TBE case distribution (1971-2000) has been prepared using remote sensing and geographical information systems technologies. The influence of climate changes on a forest ecosystem inhabited by I. ricinus has been studied in the southern region of the Czech Republic. The analysis of long-term series (1931-2000) of climatologic and phenological characteristics has been carried out. The results are compared with the long-term series of TBE incidence. The influence of weather condition on day-to-day changes of I. ricinus host-seeking activities was studied in 2001-2004. Field observations were realized in the south-eastern periphery of Prague where the experimental plots for tick monitoring were established in a relevant type of forest growth (Querceto-carpinetum). I. ricinus activities were investigated by the flagging method on three plots (200 m(2) each) in weekly intervals (March to November) during 2001-2004. The instruments for micrometeorological observations were installed between the experimental plots. Macrometeorological data were used from the nearby Czech Hydrometeorological Institute first class meteorological observatory. Simple and multiple linear regression and quadratic regression were used to test the relation between weather modification and I. ricinus host-seeking activity. Two preliminary most suitable 'models' are demonstrated.

Short-term effects of ambient particles on cardiovascular and respiratory mortality.

BACKGROUND: Particulate air pollution is associated with increased mortality. There is a need for European results from multicountry databases concerning cause-specific mortality to obtain more accurate effect estimates. METHODS: We report the estimated effects of ambient particle concentrations (black smoke and particulate matter less than 10 mum [PM10]) on cardiovascular and respiratory mortality, from 29 European cities, within the Air Pollution and Health: a European Approach (APHEA2) project. We applied a 2-stage hierarchical modeling approach assessing city-specific effects first and then overall effects. City characteristics were considered as potential effect modifiers. RESULTS: An increase in PM10 by 10 microg/m (lag 0 + 1) was associated with increases of 0.76% (95% confidence interval = 0.47 to 1.05%) in cardiovascular deaths and 0.58% (0.21 to 0.95%) in respiratory deaths. The same increase in black smoke was associated with increases of 0.62% (0.35 to 0.90%) and 0.84% (0.11 to 1.57%), respectively. CONCLUSIONS: These effect estimates are appropriate for health impact assessment and standard-setting procedures.

Climate variability and campylobacter infection: an international study.

Campylobacter is among the most important agents of enteritis in developed countries. We have described the potential environmental determinants of the seasonal pattern of infection with campylobacter in Europe, Canada, Australia and New Zealand. Specifically, we investigated the role of climate variability on laboratory-confirmed cases of campylobacter infection from 15 populations. Regression analysis was used to quantify the associations between timing of seasonal peaks in infection in space and time. The short-term association between weekly weather and cases was also investigated using Poisson regression adapted for time series data. All countries in our study showed a distinct seasonality in campylobacter transmission, with many, but not all, populations showing a peak in spring. Countries with milder winters have peaks of infection earlier in the year. The timing of the peak of infection is weakly associated with high temperatures 3 months previously. Weekly variation in campylobacter infection in one region of the UK appeared to be little affected by short-term changes in weather patterns. The geographical variation in the timing of the seasonal peak suggests that climate may be a contributing factor to campylobacter transmission. The main driver of seasonality of campylobacter remains elusive and underscores the need to identify the major serotypes and routes of transmission for this disease.

[An unusual course of invasive infection due to nontoxinogenic strain of Corynebacterium diphtheriae.].

The authors report a case of complicated sepsis caused by nontoxigenic Corynebacterium diphtheriae biotype gravis in a young immunocompetent female with no predisposing factors. She acquired the infection from her boyfriend, an asymptomatic carrier of nontoxigenic strain. The primary site of infection and subsequent sepsis was not identified. The occurence and importance of carriage and invasive infections caused by nontoxigenic strains of Corynebacterium diphtheriae are discused.