Seroprevalence study in forestry workers of a non-endemic region in eastern Germany reveals infections by Tula and Dobrava-Belgrade hantaviruses.

Highly endemic and outbreak regions for human hantavirus infections are located in the southern, southeastern, and western parts of Germany. The dominant hantavirus is the bank vole transmitted Puumala virus (PUUV). In the eastern part of Germany, previous investigations revealed Tula virus (TULV) and Dobrava-Belgrade virus (DOBV) infections in the respective rodent reservoirs. Here, we describe a seroprevalence study in forestry workers from Brandenburg, eastern Germany, using IgG ELISA and immunoblot tests based on recombinant TULV, DOBV, and PUUV antigens. Out of the 563 sera tested, 499 from male and 64 from female workers, we found 41 out of the 499 (8.2%) sera from men (mean age 47 years) and 10 out of 64 (15.6%) from the women (mean age 48 years) anti-hantavirus-positive. The majority of the 51 seropositive samples reacted exclusively in the TULV (n=22) and DOBV tests (n=17). Focus reduction neutralization assay investigations on selected sera confirmed the presence of TULV- and DOBV-specific antibodies in the forestry workers. These investigations demonstrated a potential health threat for forestry workers and also the average population in non-endemic geographical regions where TULV and DOBV are circulating in the corresponding reservoir hosts. The infections in this region might be frequently overlooked due to their unspecific and mild symptoms.

High seroprevalence for indigenous spotted fever group rickettsiae in forestry workers from the federal state of Brandenburg, Eastern Germany.

In the last decade six Rickettsia species, including Rickettsia slovaca have been characterized in Germany. All of these species could be linked to distinct clinical syndromes in humans. However, due to lack of seroepidemiological data an estimation of the prevalence and the public health impact of rickettsial infections in Germany is difficult. The aim of the present study was to determine the seroprevalence of spotted fever group (SFG) rickettsiae in a population with an elevated exposure risk to ticks. For that purpose, 559 sera of forestry workers in the federal state of Brandenburg, Eastern Germany, were screened for SFG-rickettsiae reactive IgG antibodies. Positive sera were subsequently titrated by microimmunofluorescence assay against R. helvetica, R. raoultii, R. felis, "R. monacensis" and R. slovaca. The total average IgG seroprevalence rate against SFG rickettsiae of 27.5% was found to be represented by 9.7% R. helvetica, 5% R. raoultii, 2.7% R. felis, 0.5% "R. monacensis" and 0.5% R. slovaca. The remaining 9.1% positive test results were of non-differentiable origin. IgG seroprevalences ranged from 11% to 55% in the different forestry districts. Older and male participants had a significantly higher probability for seropositivity and higher anti-rickettsia antibody titer level. In addition, the number of recent as well as the recalled lifetime tick bites was significantly associated with seropositivity and higher titers against SFG rickettsiae. In conclusion, we found an unexpected high total seroprevalence against SFG rickettsiae in forestry workers and serological evidence confirming the occurrence of R. raoultii, R. felis, "R. monacensis" and R. helvetica in the federal State of Brandenburg.

Five year follow-up after primary vaccination against tick-borne encephalitis in children.

BACKGROUND: A first tick-borne encephalitis (TBE) vaccine booster in children is currently suggested 3 years after completing either a conventional (doses on Days 0, 28 and 300) or accelerated conventional (doses on Days 0, 14 and 300) TBE immunization schedule. This recommendation, however, may not be appropriate in cases where different TBE vaccines have been used interchangeably during the primary immunization series. METHODS: To provide robust data to better inform such recommendations, TBE antibody persistence was evaluated after 3-5 years in four groups of children (aged 5-15 years): two groups previously primed with three doses of Encepur(®) Children (conventional/accelerated conventional schedule); and two groups previously primed with two doses of FSME-IMMUN(®) followed by a third dose of Encepur(®) Children (conventional/accelerated conventional schedule). Immunogenicity was evaluated using neutralization (NT) assays based on both vaccine antigens as well as on the Enzyme Linked Immunosorbent Assay (ELISA). RESULTS: In the two Encepur(®) Children groups (full series), protective NT titers of ≥10 were detected in 98-100% of children up to 5 years after their last primary vaccination, irrespective of schedule. In contrast, only 65-70% subjects in the FSME-IMMUN(®) Junior groups (mixed series) displayed NT titers ≥10 after 3 years. Thus, due to lower probability of achieving/maintaining long-term protective antibody levels (recently defined by the World Health Organization as an NT titer ≥10) after this time point, both FSME-IMMUN Junior groups were discontinued. CONCLUSION: A strong antibody response persists for at least 5 years after full primary vaccination with Encepur(®) Children. The study thus provides support for extending the time interval for a first booster dose after primary vaccination (conventional/accelerated conventional schedule) with Encepur(®) Children from 3 to 5 years.

A Novel Dynamic Model for Health Economic Analysis of Influenza Vaccination in the Elderly.

INTRODUCTION: New vaccines are being developed to improve the efficacy of seasonal influenza immunization in elderly persons aged ≥65 years. These products require clinical and economic evaluation to aid policy decisions. METHODS: To address this need, a two-part model has been developed, which we have applied to examine the potential clinical and economic impact of vaccinating elderly persons with adjuvanted trivalent inactivated influenza vaccine (aTIV) relative to conventional trivalent (TIV) and quadrivalent (QIV) vaccines. We compared outcomes in the US population for (1) aTIV in persons aged ≥65 years and QIV in all other age cohorts; (2) QIV in all cohorts; (3) TIV in all cohorts. Low, average, and high intensity seasons with low, average, and high vaccine match scenarios were compared. Probabilistic sensitivity analysis was conducted within each discrete scenario to explore the impact of variation in model inputs on potential outcomes. RESULTS: Assuming current vaccination coverage rates in the US population with (a) 25% better efficacy of adjuvanted versus non-adjuvanted vaccine against any strain and (b) 35% better efficacy of non-adjuvanted vaccine against matched B versus mismatched B strains, use of aTIV in persons aged ≥65 years and QIV in persons <65 years could reduce influenza cases by 11,166-1,329,200, hospitalizations by 1365-43,674, and deaths by 421-11,320 versus use of QIV in all cohorts. These outcomes are reflected in a corresponding increase in quality-adjusted life-years (QALYs) of 3003-94,084. If the prevalence of mismatched influenza B was >54.5% of all circulating strains, use of QIV in all cohorts would offset the clinical benefits of aTIV. Elderly aTIV or QIV vaccination was associated with improved outcomes over non-adjuvanted TIV in many of the scenarios, particularly in low match seasons of any intensity. Total cost savings (including direct and indirect healthcare costs plus productivity impacts) with aTIV in the elderly versus QIV in the whole population ranged from $27 million (low intensity, low match) to $934 million (high intensity, high match). Univariate sensitivity analysis of relative vaccine prices in the average intensity, average match scenario indicated that aTIV could be marginally cost saving relative to QIV at the currently published Medicare price for influenza vaccines offering enhanced efficacy in the elderly. Elderly vaccination with aTIV was associated with a higher overall cost compared with TIV in only two scenarios (low intensity with average or high match); the incremental cost/QALY relative to TIV was $9980 in the average match scenario and $28,800 in the high match scenario. CONCLUSIONS: Vaccination of persons aged ≥65 years with aTIV has the potential to provide clinical and economic benefit relative to QIV and TIV. The new model allows the assessment of various alternative strategies for available influenza vaccines. FUNDING: Novartis Vaccines.

Analysis of clonal type-specific antibody reactions in Toxoplasma gondii seropositive humans from Germany by peptide-microarray.

BACKGROUND: Different clonal types of Toxoplasma gondii are thought to be associated with distinct clinical manifestations of infections. Serotyping is a novel technique which may allow to determine the clonal type of T. gondii humans are infected with and to extend typing studies to larger populations which include infected but non-diseased individuals. METHODOLOGY: A peptide-microarray test for T. gondii serotyping was established with 54 previously published synthetic peptides, which mimic clonal type-specific epitopes. The test was applied to human sera (n = 174) collected from individuals with an acute T. gondii infection (n = 21), a latent T. gondii infection (n = 53) and from T. gondii-seropositive forest workers (n = 100). FINDINGS: The majority (n = 124; 71%) of all T. gondii seropositive human sera showed reactions against synthetic peptides with sequences specific for clonal type II (type II peptides). Type I and type III peptides were recognized by 42% (n = 73) or 16% (n = 28) of the human sera, respectively, while type II-III, type I-III or type I-II peptides were recognized by 49% (n = 85), 36% (n = 62) or 14% (n = 25) of the sera, respectively. Highest reaction intensities were observed with synthetic peptides mimicking type II-specific epitopes. A proportion of the sera (n = 22; 13%) showed no reaction with type-specific peptides. Individuals with acute toxoplasmosis reacted with a statistically significantly higher number of peptides as compared to individuals with latent T. gondii infection or seropositive forest workers. CONCLUSIONS: Type II-specific reactions were overrepresented and higher in intensity in the study population, which was in accord with genotyping studies on T. gondii oocysts previously conducted in the same area. There were also individuals with type I- or type III-specific reactions. Well-characterized reference sera and further specific peptide markers are needed to establish and to perform future serotyping approaches with higher resolution.

Peptide microarray analysis of in silico-predicted epitopes for serological diagnosis of Toxoplasma gondii infection in humans.

Toxoplasma gondii infections occur worldwide in humans and animals. In immunocompromised or prenatally infected humans, T. gondii can cause severe clinical symptoms. The identification of specific epitopes on T. gondii antigens is essential for the improvement and standardization of the serological diagnosis of toxoplasmosis. We selected 20 peptides mimicking linear epitopes on GRA1, GRA2, GRA4, and MIC3 antigenic T. gondii proteins in silico using the software ABCpred. A further 18 peptides representing previously published epitopes derived from GRA1, SAG1, NTPase1, and NTPase2 antigens were added to the panel. A peptide microarray assay was established to prove the diagnostic performance of the selected peptides with human serum samples. Seropositive human serum samples (n = 184) were collected from patients presenting with acute toxoplasmosis (n = 21), latent T. gondii infection (n = 53), and inactive ocular toxoplasmosis (n = 10) and from seropositive forest workers (n = 100). To adjust the cutoff values for each peptide, sera from seronegative forest workers (n = 75) and patients (n = 65) were used. Univariate logistic regression suggested the significant diagnostic potential of eight novel and two previously published peptides. A test based on these peptides had an overall diagnostic sensitivity of 69% (100% in ocular toxoplasmosis patients, 86% in acutely infected patients, 81% in latently infected patients, and 57% in seropositive forest workers). The analysis of seronegative sera performed with these peptides revealed a diagnostic specificity of 84%. The results of our study suggest that the use of a bioinformatic approach for epitope prediction in combination with peptide microarray testing is a powerful method for the selection of T. gondii epitopes as candidate antigens for serological diagnosis.

Tick-borne encephalitis (TBE) trends in epidemiology and current and future management.

Tick-borne encephalitis (TBE) is considered an international health issue, as the number of risk areas and reported cases across Europe, Russia, and parts of Asia continues to increase. The incidence of TBE has fluctuated considerably from year to year in many countries, but in the past decade the number of TBE cases has significantly increased in the Baltic states, the Czech Republic, and Germany, in addition to occurring in countries previously considered to be free from TBE, such as Denmark (specifically the main island of Zealand), France, and Italy. A number of factors have been suggested to explain the increase in incidence, including climate change, and increased travel and outdoor pursuits, placing people in increased contact with infected ticks. There is no causal treatment available once infected, but TBE can be effectively prevented by vaccination, for which several vaccines are widely available. Three vaccination schedules are available for immunization against TBE, and the recommendations for TBE vaccination vary considerably across the countries in which TBE foci are found. However, plans are in place to raise awareness of TBE and to standardize the vaccination programme across Europe, with the aim of reducing the number of future cases of TBE.

Long-term persistence of tick-borne encephalitis antibodies in children 5 years after first booster vaccination with Encepur Children.

Tick-borne encephalitis (TBE) is a serious viral infection, which can lead to permanent neurological sequelae in children. The incidence of TBE disease is increasing in many European countries and is particularly pronounced in some regional populations. Vaccination is the most effective method for preventing TBE disease and is recommended for all those living and working in TBE-endemic areas. Encepur Children is licensed for TBE vaccination in children 1-11 years of age. Following primary vaccination, booster vaccinations are recommended; however, the optimal timing for booster vaccination of children is not known. The aim of this study was to assess the persistence of TBE antibodies in children at 3 and 5 years after their first booster vaccination with Encepur Children and to re-evaluate booster vaccination recommendations. Children 1-11 years of age (n=335) who received primary TBE vaccination according to the rapid schedule (Days 0, 7, and 21) in a previous study received a booster vaccination 12-18 months later, and were invited for follow-up at 3 and 5 years post-booster. TBE antibodies were measured using a virus neutralization test (NT; in-house, Novartis Vaccines) and also using anti-TBE IgG ELISA (Enzygnost, Siemens, Germany). In this analysis, 275 of 278 (99%) subjects and all 190 (100%) subjects who completed the follow-up at 3 and 5 years, respectively, had NT titres > or = 10. Likewise, all 275 of 278 (99%) and 188 of 190 (99%) subjects tested positive by ELISA at 3 and 5 years after the booster vaccination, respectively. Based on serological data, the interval for subsequent booster vaccinations with Encepur Children can be extended from 3 to 5 years after receiving primary vaccination and a first booster vaccination 12-18 months later.