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W Haas

Publications and source records attributed to W Haas.

At least 19 recordsLinked to original sources
PubMed2006

Capture-recapture analysis to estimate the incidence of invasive meningococcal disease in Germany, 2003.

The incidence of invasive meningococcal disease (IMD) in Germany in 2003 was estimated by the two-source capture-recapture method. As a unique personal identifier was unavailable, cases with IMD tested at the National Reference Centre for Meningococci (NRZM) were matched with cases reported to the Robert Koch Institute (RKI) through the statutory surveillance system by using demographic and disease-specific variables common to both datasets. The estimated overall incidence was 1.1 IMD cases/100,000 inhabitants, with a sensitivity of ascertainment of 64.8% for NRZM and 89.4% for RKI. Case-fatality rate was estimated at 8.8%. Adjustment for heterogeneity of capture according to age, region and serogroup observed in the NRZM (but not RKI) source had minimal effect on the estimated incidence. The IMD incidence estimated by capture-recapture analysis is thus only slightly higher than through statutory surveillance data. As a degree of positive dependence between the systems cannot be ruled out, this estimate may still be an underestimate. However, under ascertainment appears insufficient to explain the low incidence of IMD in Germany compared to other European countries.

Adolescent↗
PubMed2006

[Estimation of influenza vaccine effectiveness using routine surveillance data].

The continuous antigenic drift of influenza viruses requires annual adaptation of the vaccine. Protection depends largely on the match of the variants represented in the vaccine with the viruses actually known to be in circulation and may differ considerably from season to season. Therefore studies to assess the efficacy and effectiveness of the vaccine are conducted rather sporadically on an annual basis and it would be desirable to make use of routinely available data from surveillance programs. We compared two different approaches: (1) the "screening method" where cases are identified from laboratory data and controls are taken from data on vaccination rates and (2) a second method that uses the same cases, but controls were influenza-negative individuals with influenza-like illness (also identified from laboratory data). The sensitivity of the methods to confounders that were considered as relevant was tested with a simulation. Both methods were applied to the data of the German influenza surveillance data of the season 2004/2005. The estimated effectiveness over all age groups was rather low with both methods, but comparable with other estimations from the literature. We observed differences in certain age groups between the methods as well as large differences between particular age groups within one method. Possible explanations are random variations due to low numbers in age strata and other influences not yet considered. Therefore the estimations should be interpreted with care; however, relative comparisons among seasons may still be meaningful.

Adolescent↗
PubMed2006

[Interferon-gamma assays -- description and assessment of a new tool in the diagnosis of tuberculosis].

Up to now the diagnosis of latent tuberculosis infection (LTBI) was based solely on the tuberculin skin test. However, this method offers neither 100 % sensitivity nor -- and this is in particular due to its cross-reactivity with BCG and environmental mycobacteria -- a 100 % specificity. The demand in Germany for a more reliable in vitro test is currently enhanced by the change from the multipuncture test to the intradermal (Mendel-Mantoux) test and by the uncertainty resulting from the ceased production of the tuberculin previously used in Germany. The manufacturers of immunologic test methods such as the QuantiFERON-TB Gold In-Tube (ELISA assay) and the T SPOT-TB Test (ELISPOT assay), which are based on the Interferon-gamma (IFN-gamma) production of sensitized T lymphocytes, offer their products as possible alternatives. This article explains the function of the IFN-gamma tests and gives an overview of the most recent data, possible indications and the open scientific questions to be investigated by future clinical studies. Although the new test methods have the potential to eventually prevail as an additional helpful diagnostic tool, the authors consider a complete replacement of the tuberculin skin test as premature. The IFN-gamma tests may, however, prove already now to be a useful additional diagnostic method.

Cross Reactions↗
PubMed2005

[Influenza pandemic: A real threat ?].

An influenza pandemic is not merely a theoretical threat, but an historical fact. Reliable predictions of the timing of a new pandemic or its extent are, however, impossible. A pandemic poses a threat to society at large, which can be effectively prepared for by appropriate planning and investment in supplies of vaccine doses, antiviral medication and effective monitoring systems. During the interpandemic phase, general practitioners have an important role in raising the level of immunization and providing medical care to those contracting the disease when a pandemic does break out.

Antiviral Agents↗
PubMed2005

[Future supply of tuberculin in Germany].

The manufacturers of the only tuberculin available up to now in Germany for intradermal TB tests according to Mantoux, Chiron Vaccines Behring, in 2004 unexpectedly stopped the production of the tuberculin Behring GT (GT="gereinigtes Tuberkulin"-purified protein derivative tuberculin). Only residual stocks were sold during the preceding months. The stocks of GT 10 were already depleted at the beginning of 2005, while there are small supplies left of GT 100 and GT 1000. As a temporary solution, Chiron Vaccines Behring is offering to import the Italian tuberculin Biocine PPD 5 IE lyophil produced by Chiron S.r.l. in Siena. As this is not licensed for sale in Germany, it is necessary to obtain an exceptional prescription (Einzelverordnung) according to section sign 73 (3) of the Federal Law Relating to the Manufacture and Distribution of Medicine (Arzneimittelgesetz, AMG). In the long term, Chiron Vaccines Behring plan to secure the supply of tuberculin in Germany by importing, starting in the summer of 2006, the tuberculin produced by Chiron Vaccines Evans in the UK (PPD Evans). However, these plans involve changing over to a different type of tuberculin twice within a very short period of time. Another problem is the unresolved issue of bioequivalence. Besides the above-mentioned tuberculins produced by Chiron Vaccines, a further possibility would be the import of the tuberculin PPD RT23 SSI of the Statens Serums Institute (Copenhagen/Denmark), which is recommended by the World Health Organization (WHO) as the standard tuberculin and which has already been introduced in several European countries, or of other tuberculins such as Tubersol (PPD CT68), which is used in the US. Together with the Robert Koch Institute (RKI) and the Paul Ehrlich Institute (PEI), the German Central Committee against Tuberculosis (DZK) is striving to find a solution, in view of the urgent need for an uninterrupted supply of tuberculin in Germany for diagnostic purposes and contact tracing. A uniform tuberculin should be used in all German regions as a basis to secure a standardized testing procedure and national comparability of test results. The estimated annual requirement for Germany is two million tuberculin test doses. The Statens Serum Institute is currently evaluating the possibility of licensing PPD RT23 SSI in Germany. Chiron Vaccines Behring communicated that it is not aiming to have the Biocine tuberculin licensed for Germany but intends to apply for a license for the tuberculin PPD Evans. Sanofi Pasteur MSD at this point does not intend to have a tuberculin like Tubersol (PPD CT68) licensed for Germany. Until a licensed tuberculin is again available in Germany, it would be very useful if, especially in settings where stocks of tuberculin are essential (e.g. public health services or hospital dispensaries), an exceptional import license could be obtained.

Commerce↗
PubMed2005

Polar filament discharge of Myxobolus cerebralis actinospores is triggered by combined non-specific mechanical and chemical cues.

This study presents initial evidence for the requirement of both chemical and mechanical stimuli to discharge polar capsules of Myxobolus cerebralis actinospores, the causative agent of salmonid whirling disease. The obligate need for combined discharge triggers was concluded from data obtained in a before/after experimental set-up carried out with individual locally immobilized actinospores. Homogenized rainbow trout mucus as chemostimulus and tangency of the apical region of the spores to achieve mechanical stimulation were applied subsequently. The actinospores showed discharged polar filaments exclusively when mucus substrate application was followed by touching the polar capsule-bearing region, but not when either stimulus was offered solely to the same individuals. We measured filament discharge rates to mucus preparations in a microscopic assay using supplementary vibration stimuli to ensure mechanical excitation. The actinospores responded similarly to different frequencies, which suggested a touch-sensitive recognition mechanism. Discharge specificity for salmonid mucus could not be confirmed, as mucus of common carp and bream could trigger similar filament expulsion rates. To a lesser extent homogenized frog epidermis and bovine submaxillary mucin could also stimulate the attachment reaction. In contrast, mucus of a pulmonate freshwater snail elicited no response.

Animals↗
PubMed2005

[Tuberculosis in Germany in 2001 and 2002].

The implementation of the new law on infectious diseases in 2001 and the resulting notification of more detailed variables has led to a better knowledge about the epidemiology of tuberculosis (TB) in Germany. 7,515 new cases of active tuberculosis were notified to the Robert Koch Institute in 2001, and 7,684 cases in 2002, corresponding to an incidence of 9.1 (2001) and 9.3 (2002) per 100,000 inhabitants (as per 1 October, 2003). The slight increase in new cases in 2002 is most likely due to under-notification in 2001 because of the new system, considering that the previous decline over many consecutive years is continued according to the incidence for 2003 (8.7/100,000; n = 7,184). In 2001 as well as in 2002 42 % of new TB patients were born outside Germany, and those of foreign nationality have a five-fold higher incidence on the average than German citizens. The lung remains the most affected organ (80 %). 4,230 (2001) and 4,267 (2002) were cases of open, i. e., bacteriologically confirmed, pulmonary tuberculosis potentially contagious to their immediate contacts. The resistance rates are stable in the indigenous population, while patients coming from countries with high resistance rates reflect the situation in their countries of origin. Over two thirds of TB patients in Germany are hospitalized at some point during their disease. The treatment results (78 % on the average in 2001) do not reach the WHO target of 85 %. Approximately 7 % of TB patients in Germany still die because of this infectious disease.

Disease Notification↗
PubMed2005

The life cycle of Henneguya nuesslini Schuberg & Schroder, 1905 (Myxozoa) involves a triactinomyxon-type actinospore.

The life cycle of the histozoic myxozoan parasite Henneguya nuesslini was investigated in two salmonid host species. Naive brown trout, Salmo trutta, and brook trout, Salvelinus fontinalis, were experimentally infected in two trials by triactinomyxon type actinospores from naturally infected Tubifex tubifex. In exposed common carp, Cyprinus carpio, no myxospore production was detected. The parasite formed cysts with mature myxospores in the connective tissue of the fish 102 days post-exposure. The morphology of both actinosporean and myxosporean stages was described by light microscopy and a 1417-bp fragment of the 18S rDNA gene was sequenced. Sequence analysis confirmed the absolute congruence of the two developmental stages and assisted in determining species identity. Host range, tissue specificity and myxospore measurements provided sufficiently distinctive features to confirm species validity and were thus crucial for identification. The triactinomyxon spores had 16 secondary germ cells, unique dimensions, a very opaque sporoplasm matrix and three conspicuously protruding, pyriform polar capsules. This is the first record of a Henneguya sp. life cycle with a triactinomyxon-type actinospore, which suggests a close relationship with the Myxobolus group and a polyphyletic origin of the genus Henneguya.

Animals↗
PubMed2004

Navigation within host tissues: cercariae orientate towards dark after penetration.

The survival of skin penetrating cercariae depends on information on the direction to move toward deeper layers in the epidermis (the direction of further migration) and toward the surface (direction which must be avoided when migrating). We tested the hypothesis that parasites can use their photo-sensitivity for orientation away from the light-exposed skin surface towards darker locations. Cercariae of species invading humans ( Schistosoma mansoni), birds ( Trichobilharzia ocellata) and fish ( Diplostomum spathaceum) oriented towards light sources when free swimming in cuvettes. However, they shifted to a negative photo-orientation when migrating in agar substrates after penetration and transformation to schistosomula. This is a first hint that parasites may use photo-orientation when they navigate in host tissues.

Agar↗
PubMed2004

[Calculation of the incidence of primary care visits due to acute respiratory infections].

Data collected by the German influenza sentinel of the Working Group on Influenza (AGI) do not allow calculation of the incidence of primary care visits due to acute respiratory infections (ARI). Because patients do not have to register with a particular general practitioner, the population covered by primary care physicians is unknown. Until now the incidence of primary care visits due to ARI is estimated indirectly by extrapolating the sentinel sample of physicians to the total number of primary care physicians caring for the total population. However, distortions of the estimated incidence occur in weeks with public holidays (particularly around Christmas and New Year) and when many physicians close their practice simultaneously because of vacation. We have attempted to quantify the shortage of medical services and established thresholds to correct for situations where service by medical providers is extraordinarily reduced. The suggested method avoids distortions to a large extent and makes interpretation of data during those critical periods possible. A second subject of the paper is the validation of the estimated ARI incidence in primary care practices by comparing the data to other sources such as sick leave statistics of health insurance as well as ICD-based data from a primary care network. We found that the estimated ARI incidence in primary care practices was in line with data from other sources and appears plausible.

Acute Disease↗
PubMed2004

["Emerging infectious diseases". Dengue-fever, West-Nile-fever, SARS, avian influenza, HIV].

Some emerging infectious diseases have recently become endemic in Germany. Others remain confined to specific regions in the world. Physicians notice them only when travelers after infection in endemic areas present themselves with symptoms. Several of these emerging infections will be explained. HIV is an example for an imported pathogen which has become endemic in Germany. SARS and avian influenza are zoonoses with the potential to spread from person to person. Avian influenza in humans provides a possibility for the reassortment of a potential new pandemic strain. Outbreaks of dengue fever in endemic areas are reflected in increased infections in travelers returning from these areas. Currently, West-Nile-virus infections are only imported into Germany. The timely implementation of diagnostic, therapeutic and infection control measures requires physicians to include these diseases in their differential diagnosis. To achieve this goal, good cooperation between physicians, laboratories and the public health service is essential.

Animals↗
PubMed2004

Heredity of specific host-finding behaviour in Schistosoma mansoni miracidia.

Two strains of Schistosoma mansoni were used to investigate the hereditary basis of species-specific host recognition by analysing behavioural responses of miracidia to snail-conditioned water. An Egyptian strain of S. mansoni, capable of distinguishing its host snail Biomphalaria alexandrina from other snails was cycled repeatedly through Biomphalaria glabrata, the intermediate host of a Brazilian strain known to respond even to non-susceptible snails with high intensity. After 5 cycles in the non-natural host, miracidia of the Egyptian strain still retained their preference for the original host snail. In a second experiment, host-finding behaviour of hybrids between these two parasite strains was studied. In the F1 generation, hybrids of both parental combinations showed the same low degree of specificity as the pure-bred Brazilian strain. Approximately one quarter of F2 hybrids proved to be as discriminatory as the Egyptian strain, confirming dominant Mendelian inheritance of non-specificity in schistosome miracidial host-finding behaviour. Moreover, hybrids seem to have lost the ability to develop in B. alexandrina, possibly suggesting a link between host recognition and host compatibility. The heredity of this behavioural trait is of evolutionary and epidemiological significance, since a shift to low host-finding specificity might have been a prerequisite for S. mansoni to acquire new host snails after being introduced to South America by the slave trade.

Animals↗
PubMed2004

[Recommendations for personal respiratory protection in tuberculosis].

These recommendations of the German Central Committee against Tuberculosis give an overview of the current scientific knowledge on the tuberculosis risk of health service employees and on the risk of infection in individual areas of work. The efficacy of face masks and their benefit in tuberculosis control is discussed. There are no reliable data on the efficacy of face masks in preventing infection with M. tuberculosis, nor can such data be expected in the near future, due to the complex interaction of infection-preventing measures. As rapid case finding, isolation, and immediate, effective treatment of infected patients already greatly diminish the risk of transmission, we consider face masks to be of limited use in reducing this risk. However, they may be beneficial in certain areas of work and in certain situations, particularly in the presence of elevated aerosol concentrations. The benefit of face masks depends largely on their correct application. The choice of a particular type of mask requires knowledge of the current epidemiological situation, and a competent assessment of the risk in the area of work for which it is chosen, taking into account the closeness of contact with potentially infectious tuberculosis patients.

Germany↗
PubMed2004

Prospective molecular epidemiological study on transmission of pulmonary Tuberculosis and Migration (MuT study) -- an interim report.

INTRODUCTION: In Western Europe prevalence and incidence of tuberculosis in the indigenous population is declining and TB in migrants from high prevalence countries is becoming a major issue of TB control. Resulting changes in transmission patterns need to be investigated to adapt control strategies. The MuT (Migration and Tuberculosis) study a co-operation among federal and local public health services (ODG), the National Surveillance Center (RKI) and the University has been established in Baden-Wuerttemberg to address these issues. OBJECTIVES: The goal of this ongoing study is to determine the transmission dynamics of TB in Baden-Wuerttemberg. Here, we present the first set of data on TB cases and their contacts and discuss strategies to overcome arising difficulties. METHODS: Prospective data collection of culture positive pulmonary tuberculosis cases and their contacts. Analysis of (1) routine data, (2) spatial data, (3) social interaction data, (4) molecular typing data, and (5) observational data of the implementation phase. RESULTS: The study demonstrates the capability of the study consortium to identify clusters. It provides valuable insights into current case detection and case management procedures and shows ways to improve. A set of factors has been identified that (a) facilitate and (b) discourage study participation. CONCLUSION: Collaboration among federal and local public health services (OGD), National Surveillance Center (RKI) and the University is a promising approach to investigate and improve TB control. This model has potentials for other infectious disease control.

Epidemiologic Studies↗
PubMed2003

Description of a tandem repeated DNA sequence of Echinostoma caproni and methods for its detection in snail and plankton samples.

Echinostome larval stages in the snail have a great potential as effective competitors for the control of schistosomes and adult worms can cause painful intestinal diseases in humans. Ecology and transmission of the larval stages of trematodes are poorly understood, especially because their identification in field-collected samples by microscopy is difficult. We cloned, sequenced and analysed a 192 bp tandem repreated DNA sequence of Echinostoma caproni (EcSau3A), an often discussed antagonist of Schistosoma mansoni in Biomphalaria snails. PCR primers against this sequence can detect less than 10 fg of E. caproni DNA, 2 miracidia in snails 1 day p.i., 1 metacercaria in 50 mg snail tissue and 1 cercaria in 50 mg plankton with high specificity. Methods described in this study can support the discovery of fundamental ecological principles on distribution, host specificity and epidemiology of E. caproni larvae under field conditions.

Animals↗
PubMed2003

Phylogeography of Biomphalaria glabrata and B. pfeifferi, important intermediate hosts of Schistosoma mansoni in the New and Old World tropics.

The historical phylogeography of the two most important intermediate host species of the human blood fluke Schistosoma mansoni, B. glabrata in the New World, and B. pfeifferi in the Old World, was investigated using partial 16S and ND1 sequences from the mitochondrial genome. Nuclear sequences of an actin intron and internal transcribed spacer (ITS)-1 were also obtained, but they were uninformative for the relationships among populations. Phylogenetic analyses based on mtDNA revealed six well-differentiated clades within B. glabrata: the Greater Antilles, Venezuela and the Lesser Antilles, and four geographically overlapping Brazilian clades. Application of a Biomphalaria-specific mutation rate gives an estimate of the early Pleistocene for their divergence. The Brazilian clades were inferred to be the result of fragmentation, due possibly to climate oscillations, with subsequent range expansion producing the overlapping ranges. Within the Venezuela and Lesser Antilles clade, lineages from each of these areas were estimated to have separated approximately 740 000 years ago. Compared to B. glabrata, mitochondrial sequences of B. pfeifferi are about 4x lower in diversity, reflecting a much younger age for the species, with the most recent common ancestor of all haplotypes estimated to have existed 880 000 years ago. The oldest B. pfeifferi haplotypes occurred in southern Africa, suggesting it may have been a refugium during dry periods. A recent range expansion was inferred for eastern Africa less than 100 000 years ago. Several putative species and subspecies, B. arabica, B. gaudi, B. rhodesiensis and B. stanleyi, are shown to be undifferentiated from other B. pfeifferi populations.

Africa↗
PubMed2003

Miracidia of an Egyptian strain of Schistosoma mansoni differentiate between sympatric snail species.

The host-finding behavior of miracidia of 2 strains of Schistosoma mansoni from Egypt and Brazil was studied by recording their responses to snail-conditioned water (SCW) from the Egyptian sympatric snails, Biomphalaria alexandrina, Physa acuta, Lymnaea cailliudi, and Balinus truncatus, as well as from Biomphalaria arabica and Biomphalaria glabrata. Miracidia of the Egyptian strain significantly preferred SCW from their compatible hosts B. alexandrina and B. arabica and showed no or a weak response to SCW from the other sympatric species, whereas miracidia of the Brazilian strain did not differentiate between SCW from different snail species.

Animals↗