Factors associated with keel bone damage - a longitudinal study of commercial layer flocks during the laying period.

1. Keel bone damage, such as deformations and fractures, is a severe problem regarding animal welfare in layers. To identify risk factors under commercial conditions, 33 layer flocks (22 barn, 11 free range) with white (n = 18), brown (n = 11) and mixed (n = 4) genotypes were examined.2. Keel bone status was frequently scored by palpation throughout the laying period. Data on housing and management conditions were collected. Multiple regression and Generalized Estimating Equations procedure were used for analysis.3. At 65-74 weeks of age, the prevalence of keel bone damage ranged between 26% and 74%. White genotypes and those kept in multi-tier systems developed significantly (p < 0.05) more keel bone damage than brown genotypes or those kept in single-tier systems. Wing feather condition was associated with keel bone damage (p < 0.05), while other investigated variables regarding health, housing and management were not associated.4. In conclusion, housing and management should be adapted to meet the birds' specific needs in multi-tier systems, which may vary for brown and white genotypes. Whether those differences result from genotype associated predispositions or other individual traits remains to be determined.

Plumage damage and back skin lesions in laying hens with untrimmed beak depend on rearing of pullets and genetics.

1. Within a triennial project, 34 layer flocks with untrimmed beaks were examined regularly throughout the laying period to broaden knowledge on the occurrence and development of severe feather pecking and cannibalism, as well as on factors influencing this non-desirable behaviour.2. Flocks involved 850 to 27,183 hens of seven different genetics, kept in a barn or on free-range systems. Damage to the plumage and skin was assessed in individual hens during each visit and their body weights recorded. Correlations smaller than 0.8 between different body areas for damage indicated the necessity to consider them separately. Accounting for the risk of bias due to unevenly distributed factors, regression functions were used to assess associations between pecking damage, losses and performance, housing and management conditions. In addition, temporal pattern of pecking damage for flocks with severe, medium and little damage was modelled using these functions.3. As expected, plumage damage increased with age, whereas the development of skin lesions was less consistent. From 30 weeks of age, pecking damage on the back increased remarkably in flocks with the most severe scores compared to those with medium and little damage, especially during the later laying period. Associations were found between pecking damage on the back of hens with plumage quality of pullets when entering the layer house (point of lay). Damage to the vent/cloacal region was more pronounced in white compared to brown layers. However, this did not deny the importance of factors not significant in this study.4. The study identified factors related to genetics and status of hens when entering the layer house, particularly the influence of the rearing phase.

A phase I pharmacokinetic and safety analysis of epothilone folate (BMS-753493), a folate receptor targeted chemotherapeutic agent in humans with advanced solid tumors.

Background The folate receptor alpha is selectively over-expressed in a number of human cancers. BMS-753493 is a folate conjugate of the epothilone analog BMS-748285 that was designed to selectively target folate receptor expressing cancer cells. Methods BMS-753493 was investigated in two parallel multi-institutional first-in-human phase I/IIa studies in patients with advanced solid tumors. In Study 1, patients were treated on a schedule of once daily dosing of BMS-753493 administered on Days 1, 4, 8 and 11 every 21 days with a starting dose of 5 mg daily and in Study 2, patients were treated once daily on Days 1-4 every 21 days, with a starting dose of 2.5 mg daily. Results A total of 65 patients were treated across the two studies. The maximum tolerated dose (MTD) was 26 mg in Study 1 and 15 mg in Study 2. Fatigue, transaminitis, gastrointestinal toxicity, and mucositis were dose-limiting toxicities. One patient in Study 2 developed Stevens-Johnson syndrome attributed to BMS-753493. Plasma exposures of both the conjugated and free epothilone increased in a dose related fashion in both studies and the half-life of the conjugated epothilone was 0.2-0.6 h across dose levels. No objective tumor responses were seen in either study. Conclusions BMS-753493 was generally tolerable and toxicities known to be associated with epothilone class of anticancer agents were common, although peripheral neuropathy and neutropenia appear to have been less frequent and less severe as compared to epothilones. Antitumor activity was not demonstrated and further development of BMS-753493 has been discontinued.

Comparison of retinal thickness values and segmentation performance of different OCT devices in acute branch retinal vein occlusion.

PURPOSE: To compare retinal thickness (RT) measurement and segmentation performance of time domain (TD, Stratus) and spectral domain (SD) optical coherence tomography (OCT) devices (Cirrus, Spectralis) for imaging macular oedema (ME) secondary to branch retinal vein occlusion (BRVO). METHODS: In this study, 20 eyes of 20 consecutive patients with acute BRVO were included. A total of 18 unaffected fellow eyes served as control group. RT measurement was analysed in the five inner fields of the early-treatment diabetic retinopathy grid, and proportional segmentation errors were evaluated. RESULTS: Central millimetre thickness (CMT) showed a mean difference of -64, -74, and -18 µm (P < 0.001) in the control group and -31 µm (P=0.107), -92 µm (P<0.001), and -105 µm (P=0.016) in the BRVO group, between Stratus and Cirrus, between Stratus and Spectralis, and between Cirrus and Spectralis, respectively. Mean RT showed the highest variability between different devices in the area most intensively affected by BRVO-related ME. In eyes with BRVO, 14.6% of Spectralis, 20% of Stratus, and 36.6% of Cirrus scans demonstrated moderate and severe segmentation errors. CONCLUSION: RT measurement in eyes with BRVO, by TD and SD OCT, is compromised by a significant rate of segmentation errors. Deviations are most pronounced in the areas most severely affected by ME.

[Specific alterations in the retinal microstructure in neovascular age-related macular degeneration under anti-VEGF therapy. A detailed analysis of intraretinal changes and their possible role for follow-up]. / Mikrostrukturelle Veränderungen bei neovaskulärer altersbedingter Makuladegeneration unter Anti-VEGF-Therapie. Eine detaillierte Analyse schichtspezifisch-morphologischer Alterationen und ihre mögliche Eignung im Follow-up.

BACKGROUND: High-definition raster scanning spectral-domain optical coherence tomography (SD-OCT) allows a precise assessment of retinal layers and a more detailed detection of subtle morphological alterations. The aim of this study was to observe such changes in patients with neovascular age-related macular degeneration (nAMD) under anti-VEGF therapy and to evaluate if they show characteristic and reversible properties. METHODS: The study included 20 consecutive patients with untreated nAMD. SD-OCT with an axial resolution of 6 µm and a scan velocity of up to 25,000 A-scans/s was used for high-resolution imaging of the macular region at baseline and at months 1 and 3. Characteristic changes in the retinal microstructure were documented and analyzed. RESULTS: Obvious morphological changes as well as discrete intraretinal alterations showed a clear improvement until the third month following the initial ranibizumab injection. Destructions of the neurosensory retina and the outer retinal layers were partly reversible and significantly reduced after treatment was applied. CONCLUSION: SD-OCT was able to detect additional information on specific morphological alterations within the retina. These changes showed a considerable reduction under consistent treatment indicating their potential value for monitoring treatment success in antiangiogenic strategies.

Thirty-month follow-up after intravitreal bevacizumab in progressive idiopathic macular telangiectasia type 2.

AIM: The aim of this study is to evaluate the long-term efficacy of intravitreal bevacizumab (IVB) for eyes with non-proliferative idiopathic macular telangiectasia type 2 (IMT2) and acute vision loss. METHODS: In this interventional case series, treatment-naive eyes of 13 consecutive patients with IMT2 were included. Eyes with a recent onset of visual loss were treated with 0.04 ml IVB (n=7). Fellow eyes and eyes of patients without disease progression served as control group (CG) (n=12). Follow-up examinations included ophthalmoscopy, best-corrected visual acuity (BCVA), optical coherence tomography, and fluorescein angiography (FA). RESULTS: Mean follow-up time was 32±5.7 months in the treatment group (TG) (n=7) vs 29±8.8 months in the CG (n=16). Mean BCVA increased from logMAR 0.47±0.32 at baseline to logMAR 0.33±0.31 (P=0.21) at the last visit in the TG and decreased from logMAR 0.25±0.39 to logMAR 0.30±0.40 in the CG (P=0.17). All patients in the TG showed stabilisation or improvement in vision in Snellen lines in contrast to the CG (χ(2)-test P=0.04). Patients received on average 2.3±1.3 IVB injections. Mean central millimetre thickness in TG and CG was 260±83 and 201±32 µm at baseline vs 237±69 and 199±29 µm at the last visit, respectively (P=0.23 and 0.77). FA revealed a significant decrease of the juxtafoveal staining size at month 3 (P= 0.004) and a slight reduction at the last visit (P= 0.11) in the TG. CONCLUSION: Despite an overall moderate effect of IVB treatment, individual patients experience a marked functional and morphological long-term benefit.

Morphological and functional analysis of the loading regimen with intravitreal ranibizumab in neovascular age-related macular degeneration.

AIM: To quantify and correlate the morphological and functional effects of the recommended loading regimen with intravitreal ranibizumab in neovascular age-related macular degeneration (AMD). METHODS: In a prospective, interventional clinical trial, 29 consecutive patients (29 eyes) with choroidal neovascularisation secondary to AMD received three initial monthly intravitreal injections of ranibizumab. During this loading regimen, best corrected visual acuity (BCVA) and microperimetry (MP) testing, as well as optical coherence tomography and fluorescein angiography (FA), were performed using a standardised protocol and the results correlated. RESULTS: Significant morphological and functional therapeutic effects were observed as early as 1 week following the first treatment. Throughout the loading-dose period, central retinal thickness, including intraretinal cysts and subretinal fluid, decreased fast and significantly (p<0.01); pigment epithelial detachment resolved less rapidly. The mean leakage area by FA decreased (p<0.01) and retinal function (BCVA and MP) increased significantly (both p<0.01). However, the change in morphology and function was only significant between baseline and week 1. There was no significant additional morphological or functional benefit following the second and third injection. CONCLUSION: The initial administration of intravitreal ranibizumab in neovascular AMD induced a significant effect on intra- and subretinal fluid and visual function; subsequent injections had a less pronounced effect. It remains to be determined whether this loading regimen should be mandatory in all patients or if a single dose regimen would lead to a comparable functional and morphological retinal improvement.

[Neovascular age-related macular degeneration under anti-angiogenic therapy : Subretinal fluid is a relevant prognostic parameter]. / Neovaskuläre altersbedingte Makuladegeneration unter antiangiogener Therapie : Subretinale Flüssigkeit ist ein für die Funktion wichtiger prognostischer Faktor.

BACKGROUND: Due to its progressive nature neovascular age-related macular degeneration (nAMD) is the most common cause of irreversible vision loss and blindness in people aged 60 or older. Optical coherence tomography (OCT) plays an important role in monitoring this exudative disease. However, prognostic factors for visual rehabilitation under anti-angiogenic therapy are still rare. It was the aim of this study to identify prognostic parameters based on OCT. METHODS: In this study 17 patients with nAMD were included and treated with 3 intravitreal ranibizumab injections. Stratus-OCT and Cirrus-OCT imaging were performed to identify prognostic factors. Different OCT parameters, such as the volume of subretinal fluid and the degree of serous retinal detachment in the fovea, were analyzed and correlated with visual acuity (VA). RESULTS: Baseline VA was an important prognostic factor correlating with final VA at the end of the study. Retinal thickness measured by OCT showed a correlation to VA at the time of examination but not with the final results.. The volume of subretinal fluid (SRFV) however, correlated significantly with VA at weeks 4 and 12. The degree of serous retinal detachment of the fovea did not correlate with retinal function. CONCLUSION: Data show that some retinal thickness values correlated to VA in the spectral domain OCT but not in Stratus OCT. In this study VA at baseline and the SRFV were the most important prognostic factors for VA at 3 months.. This demonstrates the important role of SRFV measurements as a relevant prognostic factor in nAMD and encourages more research into the analysis of OCT parameters in order to have a better understanding of the prognosis of individual patients receiving anti-angiogenic therapy for nAMD.

Comparison of retinal thickness measurements and segmentation performance of four different spectral and time domain OCT devices in neovascular age-related macular degeneration.

AIMS: To evaluate the reliability of different optical coherence tomography (OCT) devices and scanning patterns in the assessment of retinal thickness and segmentation performance in neovascular age-related macular degeneration (nAMD). METHODS: 28 eyes with nAMD and 10 healthy eyes were imaged using conventional time domain (TD) OCT as well as three spectral-domain (SD) OCT systems. Radial scans of 6 mm in size were compared between Stratus and Topcon OCT, in addition to raster scans of all three SD-OCT devices. Retinal thickness values were analysed. RESULTS: Spectralis SD-OCT demonstrated the highest values of all OCT devices in central millimetre thickness (CMMT), and Topcon OCT raster scans showed the lowest values. Significant correlations could be found between the CMMT measurements of Cirrus and Spectralis OCT (r = 0.87). Analyses showed best segmentation for Cirrus and Spectralis SD-OCTs. Cirrus 200x200x1024 scans showed 4% and Stratus OCT 38% moderate or severe segmentation errors. CONCLUSION: Retinal thickness values were generally higher in SD-OCT analysis. Different performances of automatic retinal thickness analysis indicate the potential of different software algorithms to quantify retinal morphology in nAMD. Further development of current algorithms may improve quantification of retinal thickness detection in the future even further.

Three-dimensional high resolution OCT imaging of macular pathology.

Raster scanning spectral domain optical coherence tomography (SD-OCT) enables realistic three-dimensional (3D) imaging of macular disease. This approach allows the clinician to investigate the diagnostic situation in detail before and during pharmacological or surgical intervention. This study demonstrates the clinical potential of SD-OCT in chorioretinal disease. Selected datasets are presented to visualize typical morphologic findings, which are identified in more than 2700 patients. Scans are presented as online assessable 3D-models. Clinically relevant structures are visualized in macular disease and highlight the importance of precise imaging, which clearly is a clinical necessity to plan and indicate modern therapeutic strategies for our patients.

[Influence of antiangiogenetic therapy on retinal thickness values in age-related macular degeneration]. / Beeinflussung von Netzhautdickenwerten durch antiangiogenetische Therapie bei altersbedingter Makuladegeneration.

BACKGROUND: This study evaluated the impact of antiangiogenetic therapy on differences in central retinal thickness (CRT) as measured with two optical coherence tomography (OCT) systems from the same manufacturer. MATERIAL AND METHODS: Data were obtained from a group of 20 patients with neovascular age-related macular degeneration before and after intravitreal treatment with ranibizumab. Imaging was performed using the Stratus and the high-definition (HD) Cirrus OCT systems. RESULTS: The mean CRT was revealed to be significantly lower as measured by OCT compared with HD-OCT before and after treatment (p<0.002). CRT differences varied more strongly before treatment than after treatment. A higher standard deviation was noted before treatment. The difference in the mean deviation of CRT measurements before and following antiangiogenetic therapy was highly significant. CONCLUSION: This study showed that differences in CRT measurements between different OCT systems were subject not only to technical differences but also to treatment effects of current antiangiogenetic strategies. These effects should be recognized because clinical studies increasingly define OCT parameters as primary or secondary outcome measures.

[Three-dimensional optical coherence tomography for evaluating the retinal architecture before and after surgery for vitreomacular traction.] / Untersuchung von vitreomakulären Traktionen vor und nach Membranpeeling mittels hochauflösendem Raster-OCT.

PURPOSE: To investigate the morphology of the vitreoretinal interface before and after delamination of epiretinal membranes using three-dimensional volumetric high-resolution optical coherence tomography (HROCT). METHODS: Extension and intensity of vitreomacular traction due to epiretinal membranes (ERM) and the architecture of retinal layers in 14 eyes of 14 patients were evaluated preoperatively using high-resolution raster scanning OCT (Cirrus prototype, resulting in a 6x6-mm field, 2 mm in depth). Additionally, stratus OCT, visual acuity testing, and fundus photography were performed. Standardized prospective follow-up was done continuously at 1, 4, and 7 days and 1 and 3 months postoperatively. RESULTS: The ERM appeared tightly adherent to the retinal surface in 85% of cases, but nevertheless could be differentiated from the retinal surface in 100%. Vertical traction forces from the ERM to the intraretinal layers were found in 93% of cases. Structural alteration of the retina was seen neither immediately following surgery nor during follow-up. After a mean of 4 weeks, the retinal structural integrity had recovered with resolution of the traction-induced deviations seen preoperatively. Mean preoperative visual acuity increased from 0.4+/-0.2 Snellen preoperatively to 0.5+/-0.2 Snellen after 3 months. Mean retinal thickness decreased from 482+/-84 mum to 328+/-80 mum after 3 months (HROCT). CONCLUSIONS: Three-dimensional HROCT imaging enables unprecedented in vivo identification of the extension and dynamics of epiretinal traction. Epiretinal membranes are clearly delineated in the en face view, and the distribution of traction forces throughout the intraretinal layers is identified down to the level of the retinal pigment epithelium. During follow-up, quantification of substantial release in retinal traction was possible and correlated to conventional OCT findings.

[Three-dimensional imaging in central serous chorioretinopathy]. / Dreidimensionale Bildgebung bei Chorioretinopathia centralis serosa.

BACKGROUND: Conventional optical coherence tomography (OCT) has brought new insights to retinal diagnostics, but it is restricted due to its low scanning speed and limited resolution. In this study, high-resolution raster scanning OCT (HR-OCT) was used to identify typical changes in central serous chorioretinopathy (CSC). METHODS: Fifteen consecutive patients with acute CSC were imaged using HR-OCT with an axial image resolution of 6 mum. The scanned area measured 6x6 mm2. Three-dimensional (3D) evaluation was performed using various analysing programmes. RESULTS: Topographic changes in CSC could be visualised with 3D reconstructions in all locations. Retinal thickness was measured with the automatic segmentation mode and quantified precisely. Results were presented in 2D and 3D maps. En-face imaging as a modality to present an integrative overview showed specific alterations in CSC. CONCLUSION: HR-OCT was able to provide essential additional information about CSC when combined with appropriate analysing programmes, allowing the identification of typical differences. Aside from precise volumetric measurements, exact localisation of pathological deviations could be achieved.

[High-resolution optical coherence tomography to evaluate vitreomacular traction before and after membrane peeling]. / Untersuchung vitreomakulärer Traktionen vor und nach Membranpeeling mittels hochauflösendem Raster-OCT.

AIM: Morphological assessment of the vitreomacular interface and intraretinal architecture using three-dimensional high-resolution optical coherence tomography (HROCT) before and after surgical delamination of epiretinal membranes and the internal limiting membrane (ILM). METHOD: The extent and intensity of traction of the epiretinal membrane (ERM) and the morphology of the individual retinal layers were investigated preoperatively in 14 eyes of 14 patients using three-dimensional HROCT (Cirrus prototype, scanned area 6x6 mm, depth 2 mm). In addition, visual acuity and ophthalmological findings (including stratus OCT) were documented. Standardized follow-up examinations were performed prospectively adhering to a protocol on days 1, 4, and 7 as well as 1 and 3 months after surgery. RESULTS: The ERM adhered closely to the retina in 85% of cases, but in 100% it was still clearly distinguishable from the retinal surface as a separate structure when using HROCT. Vertical traction through the ERM to the deepest retinal layers could be shown on HROCT in 93% of the cases. Structural alterations of the retina were not detectable either directly after surgery or subsequently. After an average of 4 weeks, the architecture of the layers was reorganized with complete regression of the preoperative tractional aberrations. The mean preoperative Snellen visual acuity of 0.4+/-0.2 increased to an average of 0.5+/-0.2. The mean preoperative retinal thickness was 482+/-84 microm and after 3 months 328+/-80 microm (HROCT). CONCLUSIONS: Examination with high-resolution optical coherence tomography allows three-dimensional visualization of the dynamics of epiretinal tractions that had not previously been obtainable. Epiretinal membranes can be clearly distinguished and their tractional effects can be traced through all retinal layers up to the pigment epithelium. As a result of the postoperative elimination of the tractions, the morphological alterations of the individual retinal layers recede already after 1 month.

[The role of Stratus OCT in anti-VEGF therapy. Qualitative and quantitative assessment of neovascular AMD]. / Die Rolle des Stratus-OCT bei der Anti-VEGF-Therapie : Qualitative und quantitative Beurteilung bei neovaskulärer AMD.

BACKGROUND: The evaluation of OCT3 during anti-VEGF therapy. METHODS: A total of 29 patients with choroidal neovascularization secondary to AMD received 3 intravitreal injections of ranibizumab. OCT examination and visual acuity testing (ETDRS) were performed before therapy onset, after 1 week and after 1, 2 and 3 months. RESULTS: The central retinal thickness (CRT) was assessed correctly by OCT in 128 out of 145 measurements. There was a distinct (84%) but not significant correlation between decrease in central retinal thickness and increase in visual acuity. Incorrect retinal layer segmentation and inadequate CRT measurements were a significant technical limitation. CONCLUSION: During anti-VEGF therapy, OCT allows documentation and quantification of morphologic retinal changes and in most cases also for an estimation of functional improvement.

Automatic segmentation in three-dimensional analysis of fibrovascular pigmentepithelial detachment using high-definition optical coherence tomography.

BACKGROUND/AIMS: A limited number of scans compromise conventional optical coherence tomography (OCT) to track chorioretinal disease in its full extension. Failures in edge-detection algorithms falsify the results of retinal mapping even further. High-definition-OCT (HD-OCT) is based on raster scanning and was used to visualise the localisation and volume of intra- and sub-pigment-epithelial (RPE) changes in fibrovascular pigment epithelial detachments (fPED). Two different scanning patterns were evaluated. METHODS: 22 eyes with fPED were imaged using a frequency-domain, high-speed prototype of the Cirrus HD-OCT. The axial resolution was 6 mum, and the scanning speed was 25 kA scans/s. Two different scanning patterns covering an area of 6 x 6 mm in the macular retina were compared. Three-dimensional topographic reconstructions and volume calculations were performed using MATLAB-based automatic segmentation software. RESULTS: Detailed information about layer-specific distribution of fluid accumulation and volumetric measurements can be obtained for retinal- and sub-RPE volumes. Both raster scans show a high correlation (p<0.01; R2>0.89) of measured values, that is PED volume/area, retinal volume and mean retinal thickness. Quality control of the automatic segmentation revealed reasonable results in over 90% of the examinations. CONCLUSION: Automatic segmentation allows for detailed quantitative and topographic analysis of the RPE and the overlying retina. In fPED, the 128 x 512 scanning-pattern shows mild advantages when compared with the 256 x 256 scan. Together with the ability for automatic segmentation, HD-OCT clearly improves the clinical monitoring of chorioretinal disease by adding relevant new parameters. HD-OCT is likely capable of enhancing the understanding of pathophysiology and benefits of treatment for current anti-CNV strategies in future.

[New perspectives in diagnostic. High-resolution optical coherence tomography for age-related macular degeneration]. / Neue Perspektiven in der Diagnostik. Hochauflösende optische Kohärenztomographie bei altersbedingter Makuladegeneration.

BACKGROUND: Recent advances in optical coherence tomography (OCT) have made it possible to increase resolution and scan velocities so that even greater central areas of the retina can be scanned. The aim of this study is to describe the possibilities offered by this new technology for age-related macular degeneration. MATERIAL AND METHODS: The study included 20 patients with confirmed active choroidal neovascularization (CNV) as well as pigment epithelial detachment (PED). Three-dimensional imaging was performed with a high-definition raster scanning OCT system (HD-OCT) with an axial resolution of 6 microm and a scan velocity of up to 20,000 A-scans/s. The scanned area measured 6 x 6 mm with a depth of 2 mm. Two-dimensional imaging was carried out with a StratusOCT (Carl Zeiss Meditec). RESULTS: Comparison of the individual slices showed improved identification of intra- and subretinal structures with the HD-OCT. Demarcation of pathological changes in individual retinal layers is possible with the HD-OCT. Summation images permit accurate localization of a scan. Topographic and volumetric evaluations enable analysis of individual compartments in the entire scanned area and are suitable for monitoring treatment of CNV with anti-VEGF therapy. The raster method decreases the dependence on exploratory methods that have been necessary until now to generate retinal thickness maps. CONCLUSIONS: This report presents initial experience in using a raster scanning HD-OCT system in patients with neovascular age-related macular degeneration and describes new evaluation functions that aid in obtaining more precise assessment of treatment effect and its impact on the retinal ultrastructure. The results of this study clearly show that development of high-resolution OCT systems in conjunction with development of novel treatment options for exudative diseases offers promising perspectives.

Prevalence of erectile dysfunction among middle-aged men in a metropolitan area in Germany.

The comparison of results of previous studies on the prevalence of erectile dysfunction is hampered due to differences in study design and research instruments including definitions used. The aim of the study was to determine the prevalence of erectile dysfunction/erectile disorder (ED) using different definitions. An epidemiological cross-sectional study was conducted between May and November 2002 in Berlin, Germany. A total of 6000 men between 40 and 79 years of age were randomly selected by the Berlin Office of Vital Statistics and were sent a questionnaire by mail. The prevalence of ED was determined using five different methods. A total of 1915 questionnaires were eligible for analysis. The five different definitions yielded age-adjusted ED prevalence rates between 18 and 48%. Age was strongly correlated with all five definitions (P<0.001). These results indicate the need for standardized criteria when conducting future studies on ED and may aid in designing public health and clinical management strategies.

Challenges and constraints to vaccination in developing countries.

The challenges and constraints to vaccinating poultry in areas where adequate infrastructure and human resources are lacking are addressed in both a technical and a socioeconomic framework. The key issues discussed are: (1) selection of an appropriate vaccine and vaccination technique, including the advantages and disadvantages of a combined vaccine against highly pathogenic avian influenza (HPAI) and Newcastle disease and addressing the differences between endemic disease and emergency disease control; (2) vaccine conservation and distribution; (3) evaluation of the flocks to be vaccinated in terms of their disease status, immunocompetence and production systems; (4) design of effective information, education and communication materials and methods with and for veterinary and extension staff as well as commercial and smallholder producers and community vaccinators in rural areas; (5) evaluation and monitoring systems for technical and socioeconomic factors that affect vaccination; (6) support and coordination of and by relevant public and private agencies; (7) the role of simultaneous implementation of other control activities in addition to vaccination; (8) the importance of assessing the costs and cost-effectiveness of various approaches to the control of HPAI, including the prevention of other endemic killer diseases and options for cost-sharing; (9) evaluation of the incentives for poultry-holders, vaccinators and vaccine producers to contribute to and participate in effective vaccination campaigns; and (10) policy development and the organizational framework for short- and long-term implementation and communication to decision-makers.