Characteristics and risk factors for symptomatic Giardia lamblia infections in Germany

Background: In developed countries, giardiasis is considered a travel related disease. However, routine surveillance data from Germany indicate that >50% of infections were acquired indigenously. We studied the epidemiological characteristics of symptomatic Giardia infections acquired in Germany and abroad, and verified the proportion of cases acquired in Germany in order to investigate risk factors for sporadic autochthonous Giardia infections. Methods: We identified Giardia cases notified by 41 local health authorities between February 2007 and January 2008 and interviewed them on their clinical symptoms, underlying morbidities, travel abroad and potential risk factors for the disease. We conducted a case-control-study including laboratory-confirmed (microscopy or antigen-test) autochthonous Giardia cases with clinical manifestations (diarrhoea, cramps, bloating) and randomly selected controls from the local population registry matched by county of residence and age-group (0-5, 6-19, ≥20 years). Secondary cases, controls with diarrhoea and persons who had travelled outside Germany in the three weeks prior to disease onset (exposure period) were excluded. We calculated adjusted odds ratios (aOR) with 95% confidence intervals (CI) using conditional logistic regression. Results: Of 273 interviewed cases, 131 (48%) had not travelled abroad during the defined exposure period. Of these 131, 85 (65%) were male, 68 (54%) were living in communities with >100,000 inhabitants and 107 (83%) were aged 20 years or older. We included 120 cases and 240 controls in the case-control study. Cases were more likely to be male (aOR 2.5 CI 1.4-4.4), immunocompromised (aOR 15.3 CI 1.8-127) and daily consumers of green salad (aOR 2.9 CI 1.2-7.2). Contact with animals (pets/farm animals) and exposure to surface water (swimming/water sports) were not associated with symptomatic disease. Conclusions: A substantial proportion of Giardia lamblia cases in Germany are indigenously acquired. Symptomatic cases are significantly more likely to be immunocompromised than control persons from the general population. Physicians should consider Giardia infections among patients with no recent history of travel abroad, particularly if they have immune deficiencies. Green salads may be an important vehicle of infection. Information campaigns highlighting this food-borne risk should emphasise the risk to persons with immune deficiencies

Decadal changes in the mode waters in the midlatitude North Pacific

Data from almost five years of current meter moorings located across the Bahamas Escarpment at 26.5 degrees N are used to investigate meridional heat transport variability in the section and its impact on transatlantic heat Aux. Estimates of heat transport derived from the moored arrays are compared to results from the Community Modeling Effort (CME) Atlantic basin model and to historical hydrographic section data. A large fraction of the entire transatlantic heat flux is observed in this western boundary region, due to the opposing warm and cold water flows associated with the Antilles Current in the thermocline and the deep western boundary current at depth. Local heat transport time series derived from the moored arrays exhibit large variability over a range of +/- 2 PW relative to 0 degrees C, on timescales of roughly 100 days. An annual cycle of local heat transport with a range of 1.4 PW is observed with a summer maximum and fall minimum, qualitatively similar to CME model results. Breakdown of the total heat transport into conventional ''barotropic'' (depth averaged) and ''baroclinic'' (transport independent) components indicates an approximately equal contribution from both components. The annual mean value of the baroclinic hear transport in the western boundary layer is 0.53 +/- 0.08 PW northward, of opposite direction and more than half the magnitude of the total southward baroclinic heat transport between Africa and the Bahamas (about -0.8 PW) derived from transatlantic sections. Combination of the results from the moored arrays with Levitus climatology in the interior and historical Florida Current data yields an estimate of 1.44 +/- 0.33 PW for the annual mean transatlantic heat Aux at 26.5 degrees N, approximately 0.2 PW greater than the previously accepted value of 1.2-1.3 PW at this latitude

A pragmatic harm reduction approach to manage a large outbreak of wound botulism in people who inject drugs, Scotland 2015

Abstract Background People who inject drugs (PWID) are at an increased risk of wound botulism, a potentially fatal acute paralytic illness. During the first 6 months of 2015, a large outbreak of wound botulism was confirmed among PWID in Scotland, which resulted in the largest outbreak in Europe to date. Methods A multidisciplinary Incident Management Team (IMT) was convened to conduct an outbreak investigation, which consisted of enhanced surveillance of cases in order to characterise risk factors and identify potential sources of infection. Results Between the 24th of December 2014 and the 30th of May 2015, a total of 40 cases were reported across six regions in Scotland. The majority of the cases were male, over 30 and residents in Glasgow. All epidemiological evidence suggested a contaminated batch of heroin or cutting agent as the source of the outbreak. There are significant challenges associated with managing an outbreak among PWID, given their vulnerability and complex addiction needs. Thus, a pragmatic harm reduction approach was adopted which focused on reducing the risk of infection for those who continued to inject and limited consequences for those who got infected. Conclusions The management of this outbreak highlighted the importance and need for pragmatic harm reduction interventions which support the addiction needs of PWID during an outbreak of spore-forming bacteria. Given the scale of this outbreak, the experimental learning gained during this and similar outbreaks involving spore-forming bacteria in the UK was collated into national guidance to improve the management and investigation of future outbreaks among PWID

An improved composite surface model for the radar backscattering cross section of the ocean surface: 2. Model response to surface roughness variations and the radar imaging of underwater bottom topography

In the companion paper we have presented an improved composite surface model for the calculation of normalized radar backscattering cross sections (NRCS) of the ocean surface. The proposed model accounts for the impact of the full two‐dimensional ocean wave spectrum on the radar backscatter and was shown to reproduce measured absolute NRCS values for a variety of radar configurations and wind speeds satisfactorily after some reasonable tuning of the input ocean wave spectrum. This paper focuses on the modulation of the NRCS in the presence of spatially varying surface currents. First, the sensitivity of the NRCS to intensity variations of different ocean wave spectral components is investigated. Then the hydrodynamic modulation of the wave spectrum over underwater bottom topography in tidal waters is computed in different ways, and the resulting radar signatures are discussed. The composite surface model yields comparable radar signatures at high (10 GHz, X band) and low (1 GHz, L band) radar frequencies, which is in much better agreement with experimental results than the predictions of a first‐order Bragg scattering model. On the other hand, measured variations of the NRCS at high radar frequencies appear to be still underestimated in some cases, which may be due to shortcomings of our description of the wave‐current interaction by conventional weak hydrodynamic interaction theory. Possible improvements of the theory are discussed, and requirements for future experiments are formulated

Remote sensing of oceanic current features by synthetic aperture radar — achievements and perspectives

It is generally accepted that synthetic aperture radar (sar) images can be quite useful for a better understanding of hydrodynamic processes in the ocean, because they provide valuable information on the location and spatial scales of oceanic features such as fronts, internal waves, and eddies. However, the retrieval of actual surface current fields from the shape and modulation depth of radar signatures is a much more challenging problem, since the imaging mechanism is a complex and nonlinear two-step mechanism which cannot be inverted easily. In this article we review the state-of-the-art in modeling radar signatures of current features, and we present the concept of an iterative scheme for inverting radar images into current fields, which will be implemented within the framework of the European project marsais. We estimate the accuracy and spatial resolution of the proposed remote sensing system on the basis of findings from recent case studies and some dedicated simulations. According to the results of our analyses, it should be possible to retrieve spatial surface current variations and current gradients from a typical spaceborne C band sar image with an accuracy on the order of 20% and a spatial resolution on the order of 50 m.Il est généralement admis que les images de radars à synthèse d’ouverture (rso) peuvent être très utiles pour la compréhension des processus hydrodynamiques dans l’océan, car elles fournissent des informations de valeur sur la position et l’importance des caractéristiques de surface océaniques, tels les fronts, les ondes internes ou les tourbillons. Cependant, la récupération des champs de courants de surface à partir de la forme et de la modulation des signatures radars est un problème bien plus délicat, car le mécanisme d’imagerie se fait en deux étapes complexes et non-linéaires qui ne peuvent être inversées facilement. Dans cet article nous présentons l’état de l’art de la modélisation de la signature radar des caractéristiques de courant et nous présentons le concept d’un schéma itératif pour l’inversion des images radars en champs de courants. Ce schéma sera implanté dans le cadre du projet européen marsais. Nous estimons la précision et la résolution spatiale du système de télédétection proposé sur la base des découvertes provenant de cas d’études récents et de quelques simulations qui leur étaient dédiées. D’après les résultats de nos analyses, il devrait être possible de retrouver les variations spatiales des courants de surface et les gradients de courant à partir d’images RSO bande C typiques avec une précision de l’ordre de 20 % et une résolution spatiale d’environ 50 m

A three‐scale composite surface model for the ocean wave–radar modulation transfer function

An improved three‐scale composite surface model for the modulation of the radar backscatter from the ocean surface by long ocean waves is presented. The model is based on Bragg scattering theory. In the conventional two‐scale model, only the geometric modulation of the radar backscatter and the hydrodynamic modulation of the short Bragg waves by the long waves is considered. In the three‐scale model, the impact of intermediate‐scale waves (wavelengths between the length of the Bragg waves and the length of the long waves which are resolved by the radar) is also taken into account, which leads to a modified theoretical ocean wave‐radar modulation transfer function (MTF). For the first time the proposed model includes not only geometric effects associated with the intermediate‐scale waves but also the additional hydrodynamic modulation of the Bragg waves. The resulting theoretical expression for the measured “hydrodynamic” MTF depends on the radar polarization as well as on the azimuthal (upwave / downwave or upwind / downwind) radar look direction. Especially for HH polarization, the predicted “hydrodynamic” MTF becomes significantly larger than expected from conventional theory. We compare model results with tower‐based scatterometer measurements at L, C, and X band (1.0, 5.3, and 10.0 GHz, respectively), which were obtained during the Synthetic Aperture Radar and X Band Ocean Nonlinearities‐Forschungsplattform Nordsee (SAXON‐FPN) experiment. The measured magnitudes and phases of the MTF are better reproduced by the proposed three‐scale model than by the conventional two‐scale model. However, the large measured “hydrodynamic” MTFs for high microwave frequencies (C and X band) are still underestimated. The agreement between model predictions and measurements can be improved if, for example, an additional variation of the wind stress over the long waves is assumed. The required wind stress modulation depends on the long‐wave slope and appears to be coupled to the hydrodynamic modulation of the surface roughness by a positive feedback mechanism