Linking monitoring and data analysis to predictions and decisions for the range-wide eastern black rail status assessment

The US Fish and Wildlife Service (USFWS) has initiated a re-envisioned approach for providing decision makers with the best available science and synthesis of that information, called the Species Status Assessment (SSA), for endangered species decision making. The SSA report is a descriptive document that provides decision makers with an assessment of the current and predicted future status of a species. These analyses support all manner of decisions under the US Endangered Species Act, such as listing, reclassification, and recovery planning. Novel scientific analysis and predictive modeling in SSAs could be an important part of rooting conservation decisions in current data and cutting edge analytical and modeling techniques. Here, we describe a novel analysis of available data to assess the current condition of eastern black rail Laterallus jamaicensis jamaicensis across its range in a dynamic occupancy analysis. We used the results of the analysis to develop a site occupancy projection model where the model parameters (initial occupancy, site persistence, colonization) were linked to environmental covariates, such as land management and land cover change (sea-level rise, development, etc.). We used the projection model to predict future status under multiple sea-level rise and habitat management scenarios. Occupancy probability and site colonization were low in all analysis units, and site persistence was also low, suggesting low resiliency and redundancy currently. Extinction probability was high for all analysis units in all simulated scenarios except one with significant effort to preserve existing habitat, suggesting low future resiliency and redundancy. With the results of these data analyses and predictive models, the USFWS concluded that protections of the Endangered Species Act were warranted for this subspecies.

Environmental factors associated with Dictyocaulus viviparus and Fasciola hepatica prevalence in dairy herds from Costa Rica

Dictyocaulosis and fasciolosis are parasitic diseases that cause considerable economic losses for owners of farm animals worldwide, with special relevance on fasciolosis because it is an emerging zoonosis. Indirect diagnosis of these diseases through analyses of bulk milk tank samples has allowed carrying out large-scale prevalence studies, while the use of geographical information systems has helped to visualize and determine those variables that affect distribution of these pathogens. This study is intended to describe the spatial distribution of Dictyocaulus viviparus and Fasciola hepatica in dairy herds from Costa Rica, as well as their associated environmental factors. Bulk milk tank samples from 526 dairy herds in the three most important dairy regions of Costa Rica were analyzed using enzyme immunoassays. Results from the farms were subjected to spatial analyses using Holdridge's life zones, relief and soil type environmental layers. Of the total bulk milk tank samples analyzed, 3.8% (n=20) and 3.6% (n=19) were positive for D. viviparus and F. hepatica, respectively. Moran's I analysis revealed the existence of potential cluster (Moran's I=1.789, z=12.726 p<0.05) for D. viviparus. Consequently, Getis-Ord General G analysis showed that the spatial distribution of positive farms in the dataset was clustered (Observed General G=0.015, variance=0.000001, z=12.823, p<0.05). No significant positive spatial autocorrelation (Moran's I=0.038, z=0.286, p>0.0.5) was observed for F. hepatica. Furthermore, a significant difference was detected in the spatial locations of both parasites (latitude p<0.05, longitude p<0.05), and about the spatial distribution of both D. viviparus negative and positive farms (latitude p<0.05, longitude p<0.05), as well as in F. hepatica negative and positive farms regarding on latitude (p<0.05), but not on longitude (p>0.05). In the case of environmental factors, significant differences were found for D. viviparus and F. hepatica with respect to types of soil, precipitation, altitudinal belts, life zones, biotemperature, and elevation.

Vaccination with recombinant paramyosin against the bovine lungworm Dictyocaulus viviparus considerably reduces worm burden and larvae shedding

Background

The lungworm Dictyocaulus viviparus, causing parasitic bronchitis in cattle, induces a temporary protective immunity that prevents clinical disease. A radiation-attenuated larvae based vaccine is commercially available in a few European countries, but has the disadvantages of a live vaccine. As a recombinant subunit vaccine would overcome these disadvantages, the parasite’s muscle protein paramyosin (PMY) was tested as a recombinant vaccine antigen.

Methods

D. viviparus-PMY was recombinantly expressed in Escherichia coli as a glutathione-S-transferase (GST)-fused protein. Emulsified in adjuvant Saponin Quil A, the protein was given intramuscularly into calves. Two independent recombinant PMY (rPMY) vaccination trials with negative control groups (first trial: adjuvant only; second trial: non-fused GST) as well as an additional positive control group in the second trial, using the Bovilis^©Dictol live vaccine to verify vaccination results, were performed. To determine the vaccination success, shedding of larvae as well as worm burden and worm sizes were analyzed. Additionally, ELISA-based determination of development of immunglobulins IgM, IgA, IgE, IgG as well as the subclasses IgG1 and IgG2 was performed. To analyze PMY localization in the bovine lungworm, immunohistochemical staining of adult worms was carried out.

Results

Immunohistochemical staining revealed that PMY is part of the bovine lungworm’s pharyngeal and body wall muscles. Vaccination with rPMY resulted in 47% [geometric mean: 67%] and 57% (geometric mean: 71%) reduction of larvae shedding in the first and second vaccination trial, respectively. Worm burden was reduced by 54% (geometric mean: 86%) and 31% (geometric mean: 68%), respectively, and worms of rPMY-vaccinated cattle were significantly shorter in both trials. Furthermore, ELISAs showed a clear antibody response towards rPMY with exception of IgE for which titers could not be detected. After challenge infection, rPMY antibodies were only exceptionally elevated among study animals indicating PMY to be a hidden antigen.

Conclusions

Even though vaccination with the attenuated live vaccine was with 94% (geometric mean: 95%) reduction in larvae shedding and 93% (geometric mean: 94%) reduction in worm burden superior to rPMY vaccination, results using the latter are promising and show the potential for further development of a recombinant PMY-based vaccine against the bovine lungworm.

Neurotoxocarosis: marked preference of Toxocara canis for the cerebrum and T. cati for the cerebellum in the paratenic model host mouse

Background

Infective larvae of the worldwide occurring zoonotic roundworm T. canis exhibit a marked affinity to the nervous tissues of paratenic hosts. In humans, most cases of neurotoxocarosis are considered to be caused by larvae of T. canis as T. cati larvae have rarely been found in the CNS in previous studies. However, direct comparison of studies is difficult as larval migration depends on a variety of factors including mouse strains and inoculation doses. Therefore, the present study aims to provide a direct comparison of both roundworm species in mice as a model for paratenic hosts with specific focus on the CNS during the acute and chronic phase of disease to provide a basis for further studies dealing with neurotoxocarosis.

Methods

C57Bl/6J mice were infected with 2000 embryonated T. canis and T. cati eggs, respectively as well as Balb/c mice infected with T. cati eggs only. On 8 time points post infection, organs were removed and microscopically examined for respective larvae. Special focus was put on the CNS, including analysis of larval distribution in the cerebrum and cerebellum, right and left hemisphere as well as eyes and spinal cord. Additionally, brains of all infection groups as well as uninfected controls were examined histopathologically to characterize neurostructural damage.

Results

Significant differences in larval distribution were observed between and within the infection groups during the course of infection. As expected, significantly higher recovery rates of T. canis than T. cati larvae were determined in the brain. Surprisingly, significantly more T. canis larvae could be found in cerebra of infected mice whereas T. cati larvae were mainly located in the cerebellum. Structural damage in brain tissue could be observed in all infection groups, being more severe in brains of T. canis infected mice.

Conclusions

The data obtained provides an extensive characterization of migrational routes of T. canis and T. cati in the paratenic host mouse in direct comparison. Even though to a lesser extent, structural damage in the brain was also caused by T. cati larvae and therefore, the potential as pathogenic agents should not be underestimated.

Lungworm Infections in German dairy cattle herds--seroprevalence and GIS-supported risk factor analysis

In November 2008, a total of 19,910 bulk tank milk (BTM) samples were obtained from dairy farms from all over Germany, corresponding to about 20% of all German dairy herds, and analysed for antibodies against the bovine lungworm Dictyocaulus viviparus by use of the recombinant MSP-ELISA. A total number of 3,397 (17.1%; n = 19,910) BTM samples tested seropositive. The prevalences in individual German federal states varied between 0.0% and 31.2% positive herds. A geospatial map was drawn to show the distribution of seropositive and seronegative herds per postal code area. ELISA results were further analysed for associations with land-use and climate data. Bivariate statistical analysis was used to identify potential spatial risk factors for dictyocaulosis. Statistically significant positive associations were found between lungworm seropositive herds and the proportion of water bodies and grassed area per postal code area. Variables that showed a statistically significant association with a positive BTM test were included in a logistic regression model, which was further refined by controlled stepwise selection of variables. The low Pseudo R² values (0.08 for the full model and 0.06 for the final model) and further evaluation of the model by ROC analysis indicate that additional, unrecorded factors (e.g. management factors) or random effects may substantially contribute to lungworm infections in dairy cows. Veterinarians should include lungworms in the differential diagnosis of respiratory disease in dairy cattle, particularly those at pasture. Monitoring of herds through BTM screening for antibodies can help farmers and veterinarians plan and implement appropriate control measures.

Treatment of third-stage larvae of Toxocara cati with milbemycin oxime plus praziquantel tablets and emodepside plus praziquantel spot-on formulation in experimentally infected cats

Toxocara cati is the most prevalent gastrointestinal helminth in cats worldwide, with cats of all ages at risk of infection. An anthelminthic treatment that not only affects the gut-dwelling stages of this parasite but is also effective against developmental stages in the tissue has the advantage that the pathology caused by migrating larvae is minimized and the need for repeated treatments is reduced. This study was conducted to evaluate the efficacy of milbemycin oxime/praziquantel tablets (Milbemax®, Novartis) against third-stage larvae of T. cati in comparison to a spot-on formulation of emodepside and praziquantel (Profender®, Bayer). Twenty-four kittens were experimentally infected with T. cati and randomly allocated to three study groups. Treatments were performed at the minimum therapeutic dosage 5 days after the experimental infection. The development of patent infections was monitored and all cats were dewormed 50 days post-infection. Efficacies were calculated based on counts of excreted worms in the treated groups compared to a negative control group. Seven of the eight cats in the negative control group developed a patent T. cati infection and all cats were excreting worms at the end of the study (geometric mean worm count 18.1). No efficacy could be observed for the milbemycin oxime-treated animals. All cats developed a patent infection and excreted worms (geometric mean worm count 27.7). The treatment with Profender® was 98.5 % effective against L3 of T. cati. One cat developed a patent infection and was excreting worms at the end of the study (geometric mean worm count 0.3). No adverse reactions were noted in either treatment group.

Bulk milk-estimated seroprevalence of Fasciola hepatica in dairy herds and collecting of risk factor data in East Frisia, northern Germany

The liver fluke Fasciola (F) hepatica is one of the most important trematodes in cattle farming worldwide. Fasciolosis in dairy cows is leading to production losses due to decreased milk yield, liver condemnation and impaired reproduction. The treatment of dairy cows is unsatisfactory, because available drugs are either effective against adult flukes only or have long withdrawal times or in some countries may not be used at all. In the present study the prevalence of F. hepatica in dairy farms located in East Frisia, which is part of the federal state Lower Saxony, was investigated. East Frisia is considered a high risk area for Fasciola hepatica infections, because of its coastal location, high precipitation and moist pastures. About 750 bulk milk samples were collected in January and November 2006 and analysed for F. hepatica antibodies using the Pourquier ELISA. In addition, questionnaires, which were answered by 260 of the participating farmers, were evaluated to analyse management-related factors associated with fasciolosis. In January and November, 52.1% and 53.6% of the bulk milk samples, respectively, showed positive results. Thereby, 88.1% of the examined farms showed an unchanged infection status, whereas 6.2% of the farms became seropositive during the grazing season and 5.8% of the dairy herds turned seronegative. Statistical analysis revealed a significant negative association between average annual milk production and the frequency of infections with F. hepatica.

Rickettsia spp. and coinfections with other pathogenic microorganisms in hard ticks from northern Germany

Rickettsia species are the causative agent of different forms of spotted fever and thus, monitored in a number of prevalence studies. The current study examined the status of ticks from the city of Hanover, Northern Germany, regarding the presence of Rickettsia spp. and coinfections with Borrelia burgdorferi sensu lato (sl) and Anaplasma phagocytophilum. In total, 1,089 questing Ixodes ricinus L. ticks were analyzed using quantitative real time polymerase chain reaction. A duplex quantitative real time polymerase chain reaction for simultaneous detection of Rickettsia spp. and Ixodes spp.-DNA as positive control for successful DNA-isolation was established. Rickettsia spp. were detected in 363 (33.3%) of the 1,089 investigated ticks. Quantification of Rickettsia showed that larvae contained up to 50,000 bacteria, nymphs up to 85 million and adults up to 200 million per tick. Species differentiation was possible in 178 out of 363 Rickettsia positive samples and resulted in a predominant occurrence of R. helvetica (98.9%, 176/178), whereas R. monacensis was rarely found (1.1%, 2/178). Besides detection of Rickettsia, positive ticks were compared with results from previous studies to examine coinfections with B. burgdorferi sl and A. phagocytophilum. The resulting coinfection rates were 9.1% (99/1,089) for B. burgdorferi sl and 2.8% (11/391) for A. phagocytophilum. Triple-infection with Rickettsia spp., B. burgdorferi sl, and A. phagocytophilum occurred in 5 (1.3%) out of 391 ticks. The current study is the first presenting quantitative data concerning the load of Ixodes ticks with Rickettsia individuals.

Genes of the bovine lungworm Dictyocaulus viviparus associated with transition from pasture to parasitism

Genes necessary to enable nematode parasitic life after free-living larval life are of substantial interest to understand parasitism. We investigated transcriptional changes during transition to parasitism in the bovine lungworm Dictyocaulus viviparus, one of the most important parasites in cattle farming due to substantial economic losses. Upregulated transcripts in either free-living, developmentally arrested L3 or parasitic immature L5 were identified by suppression subtractive hybridization (SSH) followed by differential screening and subsequent virtual Northern blot verification. From 400 sequenced clones of parasitic L5, 372 (93.0%) upregulated high quality ESTs were obtained clustering into 30 contigs and 38 singletons. Most conceptual translated peptides were SCP/TAPS "family" members also known as pathogenesis-related protein (PRP) superfamily (28.5% of total ESTs), cysteine proteases (24.5%), and H-gal-GP orthologues (9.9%). These proteins are predicted to play key roles in fundamental biological processes such as nutrition and development but also parasite-host interactions and immune defense mechanisms. Increased energy requirement of the rapidly developing L5 lungworm stage was obvious in a proportion of 12.2% upregulated ESTs being components of the respiratory chain. From the developmentally arrested L3 stage sequencing of 200 clones resulted in 195 high quality ESTs (97.0%) clustering into 7 contigs and 3 singletons only. Besides a hypothetical protein (70.1% of total ESTs) most transcripts encoded the cleavage stimulation factor subunit 2 (17.5%), which is a component of the poly(A(+)) machinery and found to be involved in gene silencing. Obtained data provide the basis for future fundamental research into genes associated with parasitic lifestyle but also applied research like vaccine and/or drug development.

Strongyloides papillosus: changes in transcript levels of lysozyme and aspartic protease 2 in percutaneously migrated larvae

The infection of the host is the crucial event in the life-cycle of parasites. To understand the molecular mechanisms of this important step, different methods are used in present studies. For analysis of changes in transcript levels the most sensitive method is the quantitative real-time PCR (qPCR). For an accurate analysis the evaluation of a set of adequate reference genes is necessary. The present study aimed to analyse the transcriptional levels of two genes of interest, the putative aspartic protease Spa-asp-2 and the putative lysozyme Spa-lys, in infective, free-living larvae of Strongyloides papillosus at different ages and from long-term and short-term infections and percutaneously migrated ("parasitic") larvae. Percutaneously migrated larvae were collected using the PERL chamber system and ovine skin in vitro. Reference genes identified as most suitable for transcriptional analysis according to geNorm analysis were genes for the eukaryotic translation elongation factor 1 alpha (Spa-eft-2), actin variation 2 (Spa-act-v2) and beta tubulin (Spa-tbb-1). Transcriptional analysis of the genes in percutaneously migrated larvae showed an upregulation of Spa-asp-2, while Spa-lys was downregulated. Data from the presented study provide a first glance into the changes of transcript levels of S. papillosus induced by percutaneous migration.

Borrelia burgdorferi sensu lato and Rickettsia spp. infections in hard ticks (Ixodes ricinus) in the region of Hanover (Germany)

In a total of 605 Ixodes (I.) ricinus ticks collected in the spring-months March, April and May 2005, quantitative real time PCR (qPCR) revealed 26.6% Borrelia (B.) burgdorferi sensu lato (sl)-positive ticks, i. e. divided by sex and stage into 31.9% positive adults (34.8% females and 29.0% males) and 18.5% positive nymphs. Mono-infections with genospecies from the B. burgdorferi sl-complex were found in over two thirds of the positive individuals, whereas almost one third showed double- or even triple-infections. Genospecies-specific conventional PCR determined B. afzelii as the most frequent genospecies followed by B. garinii, B. spielmanii, B. valaisiana and B. burgdorferi sensu stricto (ss). Rickettsia spp. were found in 34.2% of the collected ticks, divided into 37.6% adults (42.5% females and 32.8% males) and 29.0% nymphs. Co-infections of Rickettsia-positive ticks with B. burgdorferi sl spirochaetes were present in 10.1% of the ticks. Thereby, adult ticks exhibited a co-infection rate of 13.4% (15.5% females and 11.3% males) and nymphs of 5.0%. Independently of the above mentioned study, 3939 Ixodes ticks, sent in between 2006 and 2010 for B. burgdorferi sl-diagnostic, were examined by qPCR exclusively for B. burgdorferi sl. The resulting B. burgdorferi sl prevalence was 23.1% and 24.4% in 2006 and 2007, respectively, followed by a continuous decrease to 12.8% in 2010. To analyse whether this observed decrease in infection frequency is due to sampling bias, in a current study randomly sampled ticks collected from defined sites equally distributed over the city of Hanover are investigated in a statistically relevant sample size.

Prevalence of Anaplasma phagocytophilum and coinfection with Borrelia burgdorferi sensu lato in the hard tick Ixodes ricinus in the city of Hanover (Germany)

The castor bean tick Ixodes ricinus has been found to be the main vector for Lyme borreliosis spirochetes and Anaplasma phagocytophilum in Central Europe. 1646 I. ricinus ticks from Hanover, a city located in Northern Germany, were examined for infection with A. phagocytophilum and coinfection with Borrelia burgdorferi sensu lato (sl) to obtain so far missing prevalence data for this region. The total A. phagocytophilum infection rate was 3.2% (52/1646 ticks), divided into 4.1% (32/777) adults and 2.3% (20/869) nymphs. Coinfections with B. burgdorferi sl were found in 0.9% of all tick stages. The detected genospecies were B. afzelii, B. garinii, B. burgdorferi sensu stricto (ss), and B. garinii, which was the most frequent species in coinfected ticks.

In vitro studies on the sexual maturation of the bovine lungworm Dictyocaulus viviparus during the development of preadult larvae to adult worms

The bovine lungworm Dictyocaulus viviparus is one of the most important parasites in grazing cattle. However, not much is known about morphology and molecular aspects of sexual maturation occurring during development of preadult larvae (L5) to adults. Since studies in the pulmonary compartments are infeasible, an in vitro cultivation method was established. The study was conducted with L5 during in vitro cultivation, assessing longitudinal growth and sexual maturation. Best results were achieved with RPMI-1640 medium with L-glutamine, 50% fetal bovine serum, amphotericin B (0.25 mg/ml), penicillin (10,000 U/ml), and streptomycin (10 mg/ml) at 39°C and 5% atmospheric CO₂. During cultivation, individuals grew from an average length of 4.64 to 9.88 mm independent of their density per setup. Regarding sexual maturation, female individuals started to lay eggs, whereas the testes of male individuals were filled with spermatozoa. Consequently, adult female and adult male worms developed. However, no copulation was observable and eggs did not embryonate. Development was further investigated by quantitative real-time PCR transcriptional analysis of major sperm protein (msp) and vitellogenin (vit) representing male and female sexual development, respectively. Male msp transcription peaked after 5 days of cultivation [corresponding to 20 days post infection (dpi)] and decreased gradually afterwards. Female vit transcription showed the highest rate after 15 days of cultivation (30 dpi), however it never reached the transcription rate in female adults isolated from the host. All in all, the present study gives not only insights into morphological differentiation but provides data lightening molecular aspects of sexual maturation in D. viviparus.

Dynamics of distribution and efficacy of different spot-on permethrin formulations in dogs artificially infested with Dermacentor reticulatus

BACKGROUND

Varying reports concerning the duration and reliability of different permethrin preparations' efficacy can be found in the literature. The aim of this study was to investigate the dynamics of the distribution and efficacy of four different spot-on formulations with permethrin as the active ingredient formulated with different solvents. To examine the influence of these solvents on the speed of distribution and the acaricidal activity of permethrin in the coat, an in vivo study under laboratory conditions was performed. Six dogs per test period were treated with the recommended dose and 1, 14 and 28 days after treatment dogs were infested with Dermacentor reticulatus ticks: a) on the back, near the application site, and b) on the hind leg, the greatest possible distance from the application site. Efficacies were determined 6 hours after tick infestation to examine the repellent effect and the speed of kill of the products which plays an important role in the context of tick transmitted diseases.

RESULTS

After six hours of exposure, a significant acaricidal efficacy (p < 0.001) could be observed in all treated groups over the whole duration of the study, regardless of which product was used. While the arithmetic mean of attached ticks was < 3 on Day 1, numbers increased over the course of the study to a mean of > 9 on Day 28. However, most of these ticks were dead even 28 days after treatment, as the mean of live attached ticks was still < 2. Significant differences could neither be found between the different permethrin spot-on formulations, nor between the two parts of the body (p > 0.05).

CONCLUSIONS

All products were able to kill ticks within six hours following infestation from Day 1 to Day 28 after treatment. Additionally, no significant difference between the tick numbers on the back and the hind leg could be found at any time, which implies a homogenous distribution of permethrin over the body. The efficacy of all four products was comparable during the whole study period, showing that the different solvents do not significantly affect the dynamics of distribution.

Larval migration in PERL chambers as an in vitro model for percutaneous infection stimulates feeding in the canine hookworm Ancylostoma caninum

Background

Ancylostoma caninum third-stage larvae are the non-feeding infective stage of this parasite and are able to infect potential hosts via different infection routes. Since percutaneous infection is one of the most important routes and skin penetration is the first step into parasitic life, an existing in vitro model for percutaneous migration was modified and evaluated. The main parameter used to evaluate migration was the migration ratio (migrated larvae as a percentage of total number of larvae recovered). Additionally, the skin lag was calculated, expressing the percentage of larvae remaining in the skin and therefore not being recovered. Since initiation of feeding is proposed to be an important step in the transition from free-living to parasitic A. caninum larvae, feeding assays were performed with in vitro percutaneously migrated larvae. Additionally, infective larvae of A. caninum were activated via serum-stimulation and feeding behaviour was analysed and compared between percutaneously migrated and serum-stimulated larvae.

Results

Maximum skin migration levels of infective larvae were observed at temperatures above 32°C when larvae were placed on the epidermal side of skin for more than 12 hours. The medium beneath the skin had no effect on migration ratio, and no significant difference between the migration ratios through fresh and frozen/thawed skin was observed.

Maximum feeding levels of 93.2% were observed for percutaneously migrated larvae after 48 h incubation, whereas serum-stimulated larvae reached the maximum of 91.0% feeding larvae after 24 h.

Conclusions

The PERL chamber system was optimised and standardised as an in vitro model for percutaneous migration. The larvae recovered after percutaneous migration showed characteristic signs of activation similar to that of serum-stimulated larvae. The observed difference in time course of resumption of feeding indicates that percutaneously migrated larvae are not identical to serum-stimulated larvae, which are currently representing the model for early parasitic stages.

Occurrence of Bartonella henselae and Borrelia burgdorferi sensu lato co-infections in ticks collected from humans in Germany

Bartonella (B.) henselae is the zoonotic agent of cat scratch disease. B. henselae has been associated with therapy-resistant Lyme disease in humans suggesting that B. henselae and Borrelia burgdorferi sensu lato might be transmitted concurrently by ticks. In the present study we found that 16 (6.9%) of 230 Ixodes ricinus collected from humans harboured DNA of Bartonella spp. Fifteen positive ticks were infected with B. henselae and one tick with B. clarridgeiae. Twenty-five percent of the 16 Bartonella positive ticks were co-infected with Borrelia burgdorferi sensu lato. Our data show that B. henselae is present in Ixodes ricinus and that ticks may serve as source of infection for humans.

Larval development of Toxocara canis in dogs

The parasitic roundworm Toxocara canis is present in dog populations all over the world. Due to its zoonotic potential, this roundworm is of special interest not only for veterinarians, but also for medical practitioners. In the present review, current knowledge of infection routes and the subsequent development of larvae within the canine host is summarised. Furthermore, information about the clinical, pathological, enzymatic, haematological and histopathological changes was collected, giving a broad overview of current knowledge of the infection. Although the data collected over the years give an idea of what happens during the larval development of T. canis, many questions remain open. Nevertheless, it is important that we continue our efforts to further understand the biology of this versatile and compelling parasite and try to improve and optimise strategies to prevent the infection in dogs and thereby to protect humans from this infection.

Seroprevalence of Taenia saginata cysticercosis in the federal state of Lower Saxony in Germany

Based on ELISA results from randomly selected serum samples taken from 128 cattle from different administrative and urban districts in the federal state of Lower Saxony in Germany a seroprevalence estimate of Taenia saginata cysticercosis in this area was derived. This estimate was subsequently used to calculate the sample size required in an epidemiological study to determine the actual prevalence of this infection in the cattle population (n = 2 604 767) in this federal state. The sample size was calculated as 1518 and the samples were collected according to the distribution of cattle among the 48 administrative and urban districts in Lower Saxony. The samples were tested with an evaluated antibody ELISA. The results showed a positive antibody titre rate of 8.83% from the total tested samples.

Giardia in symptomatic dogs and cats in Europe--results of a European study

The percentage of Giardia infection in dogs and cats with gastrointestinal signs presenting to clinics was examined across Europe using the IDEXX SNAP Giardia Test (IDEXX Laboratories). Veterinary practices were asked to identify diarrheic and/or vomiting dogs and cats and to use the test on fecal samples from these animals. A selection for "asymptomatic" testing was also available on the data collection sheet for testing that occurred outside the target "symptomatic" population. Results from 8685 dogs and 4214 cats were submitted during the sampling period from 2005 to 2006. Analysis of the data showed 24.78% of the samples positive for Giardia among tested dogs and 20.3% among tested cats. The younger the dog or the cat, the higher the risk of being positive, peaking in the category below 6 months. The main clinical symptom, diarrhoea, also showed a higher risk of being positive, OR's of acute diarrhoea were almost double of those of the category "asymptomatic" for dogs or cats, the same range was calculated for chronic diarrhoea. Differences in participating countries were also seen. The risk of being positive was half or less in UK, Spain, Netherlands, Italy compared to Germany, and only in Belgium it showed to be higher. The results of this study show that Giardia is a common enteric agent among dogs and cats with gastrointestinal signs in Europe.

Treatment and prevention of vertical transmission of Toxocara cati in cats with an emodepside/praziquantel spot-on formulation

This study aimed to determine the efficacy of emodepside 2.14%/praziquantel 8.58% topical solution (Profender, Bayer) in the prevention and treatment of lactogenic Toxocara cati infections. Eight pregnant cats were orally infected with T. cati eggs during late pregnancy. Four queens were treated on day 60 post conception and four queens were left untreated. The kittens of two untreated queens were treated 28 days after birth. The two other negative control litters were left untreated. The efficacy of emodepside was determined by faecal egg counts. While faecal samples of queens and litters in the control group became positive for T. cati, egg shedding was completely prevented in all four treated queens, in their litters and in the kittens from the two litters which were treated four weeks after birth. The untreated mothers of the latter stayed also coproscopically negative, which might be explained by an oral uptake of emodepside through grooming. The treatment was well tolerated by pregnant queens as well as by four-weeks-old kittens.To our knowledge, this is the first publication that focuses on the prevention of lactogenic transmission of T. cati.

Putative G protein-coupled receptors in parasitic nematodes--potential targets for the new anthelmintic class cyclooctadepsipeptides?

Parasitic nematodes cause major problems in livestock animals. Resistances to the most commonly used drugs are arising. The cyclooctadepsipeptide emodepside belongs to a new class of anthelmintics. A receptor for emodepside, Hc110-R, was previously identified in Haemonchus contortus. We have identified the complete coding sequences of putative orthologues in Cooperia oncophora and Ostertagia ostertagi, tri-chostrongyles in cattle. The putative receptors were named depsiphilins. The deduced amino acid sequence of C. oncophora depsiphilin has a similarity of 91% to the O. ostertagi sequence. The similarity of both the C. oncophora and O. ostertagi depsiphilin to Hc110-R is 89%, based on the amino acid sequence. The depsiphilins share 46% identity with the latrophilin-like protein 1 in Caenorhabditis elegans and 47% identity with a hypothetical protein in Caenorhabditis briggsae. Hc110-R and the latrophilin-like proteins of C. elegans were previously reported to be putative G protein-coupled receptors (GPCRs) and to be related to mammalian latrophilins. A seven transmembrane domain, a GPCR proteolytic site, and other conserved domains characteristic of receptors of the latrophilin group were identified within the depsiphilins. Therefore it seems reasonable to allocate the depsiphilins to the previously described latrophilins and latrophilin-like proteins.

Efficacy of toltrazuril as a metaphylactic and therapeutic treatment of coccidiosis in first-year grazing calves

A multicentric, placebo–controlled, randomised, blinded and blocked field study was conducted to evaluate the efficacy and safety of toltrazuril (Baycox^®, Bayer AG, Leverkusen, Germany) in the treatment of coccidiosis in first–year grazing calves naturally infected with Eimeria spp. Three–hundred and thirty–one calves were enrolled in the study and allocated to one of two treatments at a ratio of 1:1. One hundred and sixty–seven animals were treated once orally with 15 mg/kg toltrazuril, and 164 animals served as placebo–treated controls. Two treatment regimes were compared, a metaphylactic (treatment on the day, or 1 day after, turn out) and a therapeutic treatment (4 or 7 days after turn out). During an observation period of 14 days after treatment the animals were clinically examined for diarrhoea and faecal samples were regularly assessed for Eimeria oocysts. Other possible causes of diarrhoea were excluded on the basis of microbiological and virological examination. Animals were predominantly infected with Eimeria alabamensis. Number of days with diarrhoea in animals treated with toltrazuril was significantly lower compared to the placebo–treated group (therapeutic treatment: P=0.0024; metaphylactic treatment: P<0.0001). Furthermore, the number of animals with diarrhoea during the observation period for a minimum of at least 3 days, the number of animals positive for Eimeria oocysts, and the number of animals with both diarrhoea for a period of at least 3 days and positive for Eimeria oocysts, were signiflicantly lower (P<0.01), in the toltrazuril– compared to the placebo–treated animals. Body weight in the toltrazuril–treated animals significantly exceeded that of the placebo–treated animals at the end of the observation period. Mean difference in body weight was higher in the metaphylactic (+7.3 kg) compared to the therapeutic treatment group (+3.4 kg). No adverse reactions were observed. The results indicate that toltrazuril is highly efficacious and safe in the metaphylactic and therapeutic treatment of coccidiosis caused by E. alabamensis in first–year grazing calves.

The use of bulk-tank milk ELISAs to assess the spatial distribution of Fasciola hepatica, Ostertagia ostertagi and Dictyocaulus viviparus in dairy cattle in Flanders (Belgium)

Fasciola hepatica, Ostertagia ostertagi and Dictyocaulus viviparus are helminth parasites with a wide distribution and an important economic impact in cattle in temperate climates. This paper describes the spatial distribution of F. hepatica, O. ostertagi and D. viviparus in dairy herds in Flanders (Belgium). One thousand eight hundred herds were selected at random from the Flemish dairy population (n=7002), stratified on community level to obtain a sample representative for the entire study area. From each herd, a bulk milk sample collected in autumn 2006 was analysed with previously described antibody-ELISAs in order to identify herds where the parasite infection level is likely to cause production loss (F. hepatica and O. ostertagi) (defined as economic infections) or where patent infections have been present over the past grazing season (D. viviparus). The herd prevalence of economic infections with F. hepatica and O. ostertagi was 37.3% (95% Confidence Interval (CI): 35.1-39.7) and 59.1% (95%CI: 56.8-61.4), respectively. The herd prevalence of D. viviparus was 19.6% (95%CI: 17.7-21.6). On 28.9% (CI 26.8-31.3) of the herds, low levels of infection were observed for all three of the helminths. The presence of clustering of (economic) infections was studied using Moran's I, whereas the location and size of the clusters were studied using the spatial scan statistic, the Local Indicator of Spatial Association and Kernel density plotting. A marked clustering in the spatial distribution of F. hepatica and a mild clustering in the spatial distribution of O. ostertagi were observed. D. viviparus infections were spread evenly over Flanders. Knowledge of locations of high risk areas can lead to increased awareness and may be the start of the development of regionally adapted control measures.

Stage-dependent transcriptional changes and characterization of paramyosin of the bovine lungworm Dictyocaulus viviparus

The bovine lungworm Dictyocaulus viviparus is of major economic importance in cattle farming in the temperate zones. The invertebrate protein paramyosin is one of the main components of muscle thick filaments but can also exhibit immunomodulatory functions. It represents a promising vaccine candidate in parasitic helminths. In this study, D. viviparus paramyosin (DvPmy) was characterized on the transcriptional as well as genomic level. The identified genomic sequence comprises 19 introns compared to only 10 introns in the Caenorhabditis elegans orthologue. Quantitative real time PCR transcriptional analysis revealed paramyosin transcription throughout the whole parasite's life cycle with the highest transcription rate in the agile moving first-stage larvae and the lowest in motionless hypobiosis induced third stage larvae. Recombinantly expressed DvPmy was found to bind collagen and IgG. Thereby the present study is the first showing that nematode paramyosin has the capability for immunomodulation and thus may be involved in host immune defence.

Molecular characterization and real-time PCR transcriptional analysis of Dictyocaulus viviparus major sperm proteins

Major sperm proteins (MSPs) represent a protein family occurring in nematodes only. Identification of the 3' and 5' untranslated region (UTR) completed the so far partial msp complementary DNA sequences of the bovine lungworm Dictyocaulus viviparus. The full-length transcript contains sequence tracts consistent with the Kozak and polyadenylation consensus sequence. On genomic level, three full-length sequences differing in three nucleotides were determined containing a 65-bp phase zero intron. Conceptual translation inferred two MSP isoforms due to one substitution within the 126-amino acid polypeptide. Bioinformatic analysis predicted that bovine lungworm MSP folds into an immunoglobulin-like seven-stranded beta sandwich as known for Caenorhabditis elegans and Ascaris suum. Furthermore, bovine lungworm MSP is confidentially predicted to be N-terminal-acetylated and secreted via a non-classical pathway. Quantitative real-time polymerase chain reaction analysis using ten developmental lungworm stages showed that msp is transcribed mainly in adult male parasites and in some degree in hypobiotic L5. However, marginal msp transcription was detectable in all of the investigated developmental lungworm stages.

Evaluation of reference genes for quantitative real-time PCR to investigate protein disulfide isomerase transcription pattern in the bovine lungworm Dictyocaulus viviparus

Quantitative real-time PCR (qPCR) is the most sensitive technique for transcript quantification provided that gene transcription patterns are normalized to an evaluated reference gene. For Dictyocaulus viviparus, the housekeeping genes beta-tubulin, beta-actin, elongation factor 1alpha (ef-1alpha), glyceraldehyde-3-phosphatase dehydrogenase (gapdh), and 60S ribosomal protein L37a (60S rpL37a) were characterized and evaluated. Evaluation using the geNorm software revealed ef-1alpha and beta-tubulin as the most suitable reference genes, whereas the coefficient of variation approach resulted in ef-1alpha and 60S rpL37a as transcripts with the least variation among 12 developmental lungworm stages. The critical influence of reference genes on qPCR data analysis, with the possible consequence of erroneous, misleading results due to inappropriate reference genes used for data normalization, is shown for protein disulfide isomerase 2 (pdi-2) transcription patterns. Proper normalization of pdi-2 transcription using ef-1alpha and beta-tubulin as reference genes resulted in a more than 7-fold enriched pdi-2 transcription in L1 compared to that in eggs, and a dramatic decrease in L3. Following an increase in the L5 stage there is again a decrease of pdi-2 transcription in adult lungworms. These fluctuations in the transcription levels reflect the requirement of cuticule collagen during bovine lungworm development.

Comparative efficacy of imidacloprid, selamectin, fipronil-(S)-methoprene, and metaflumizone against cats experimentally infested with Ctenocephalides felis

Four active ingredients--imidacloprid selamectin, fipronil-(S)-methoprene, and metaflumizone--were tested to assess the speed of flea kill against existing flea infestations and subsequent reinfestations. Thirty flea-infested cats were allocated to four treatment groups and one untreated control group. Flea counts were performed 6, 18, and 48 hours after treatment (day 0) and 2, 4, and 24 hours after weekly flea reinfestations. Cats were also reinfested with fleas after the 6- and 18-hour counts on day 0 and after the 2- and 4-hour counts on subsequent count days. Imidacloprid provided significantly greater flea kill at diverse time points. At the 24-hour counts, all compounds showed expected and similar high efficacies. On study day 34, imidacloprid showed the highest efficacy at 24 hours after reinfestation, with 90.8% flea reduction compared with 55.7% to 67.4% in the other treatment groups. A single topical application of imidacloprid provided a high efficacy in the early elimination of adult fleas, limiting the risk of pathogen transmission and flea allergy dermatitis.

Prevalence of Toxocara spp., Toxascaris leonina and ancylostomidae in public parks and beaches in different climate zones of Costa Rica

This epidemiological study was conducted in different regions of Costa Rica to determine the prevalence of the developmental stages of potential zoonotic intestinal helminths of dogs and cats in public places. Samples were collected within three main climate zones including rural and urban areas during both the rainy and the dry season. Faecal and environmental samples were taken from 69 parks and beaches. Of the faecal samples 3% contained Toxascaris spp. eggs, 7% Toxocara spp. eggs and 55% contained ancylostomidae eggs. Of the soil samples, 2% contained ancylostomidae eggs and 0.8% contained ascarid eggs. Significant differences in the presence of parasites were found in faecal samples of dry, moist and wet climate zones and between the dry and rainy seasons. Significant differences in the presence of eggs and larvae were also found in the grass samples in the dry, the moist and the wet climate zones and between the different seasons. No significant differences were found between rural and urban areas.

A transcriptomic analysis of the adult stage of the bovine lungworm, Dictyocaulus viviparus

Background

Lungworms of the genus Dictyocaulus (family Dictyocaulidae) are parasitic nematodes of major economic importance. They cause pathological effects and clinical disease in various ruminant hosts, particularly in young animals. Dictyocaulus viviparus, called the bovine lungworm, is a major pathogen of cattle, with severe infections being fatal. In this study, we provide first insights into the transcriptome of the adult stage of D. viviparus through the analysis of expressed sequence tags (ESTs).

Results

Using our EST analysis pipeline, we estimate that the present dataset of 4436 ESTs is derived from 2258 genes based on cluster and comparative genomic analyses of the ESTs. Of the 2258 representative ESTs, 1159 (51.3%) had homologues in the free-living nematode C. elegans, 1174 (51.9%) in parasitic nematodes, 827 (36.6%) in organisms other than nematodes, and 863 (38%) had no significant match to any sequence in the current databases. Of the C. elegans homologues, 569 had observed 'non-wildtype' RNAi phenotypes, including embryonic lethality, maternal sterility, sterility in progeny, larval arrest and slow growth. We could functionally classify 776 (35%) sequences using the Gene Ontologies (GO) and established pathway associations to 696 (31%) sequences in Kyoto Encyclopedia of Genes and Genomes (KEGG). In addition, we predicted 85 secreted proteins which could represent potential candidates for developing novel anthelmintics or vaccines.

Conclusion

The bioinformatic analyses of ESTs data for D. viviparus has elucidated sets of relatively conserved and potentially novel genes. The genes discovered in this study should assist research toward a better understanding of the basic molecular biology of D. viviparus, which could lead, in the longer term, to novel intervention strategies. The characterization of the D. viviparus transcriptome also provides a foundation for whole genome sequence analysis and future comparative transcriptomic analyses.

Dynamics of infections with gastrointestinal parasites and Dictyocaulus viviparus in dairy and beef cattle from Costa Rica

A longitudinal survey was carried out to determine and describe the prevalence and intensity of gastrointestinal parasite infections and Dictyocaulus viviparus in a dairy and a beef cattle farm of two different ecological zones in Costa Rica. The influence of anthelmintic treatment, age and meteorological factors (rainfall, minimum and maximum temperatures) on gastrointestinal nematodes and D. viviparus counts was determined. Calves were subjected to monthly sampling of feces and blood between April 2002 and March 2003. Coprological techniques were used to detect gastrointestinal helminthes, protozoan and D. viviparus. Blood samples were analyzed for antibodies to D. viviparus by ELISA. The most prevalent gastrointestinal parasites detected on both farms (dairy cattle, A; beef cattle, B) were Eimeria spp. (94.7%, 93.7%), Strongylidae (75.0%, 81.4%), Buxtonella sulcata (38.0%, 21.6%) and Strongyloides papillosus (29.8%, 31.7%), whereas Moniezia benedeni (4.8%, 9.1%), Trichuris spp. (7.3%, 13.2%), Toxocara vitulorum (0.0%, 1.8%) and Entamoeba bovis (2.5%, 1.1%) were less prevalent. Mean fecal egg counts (FEC) showed highest values of Strongylidae in April, May and July (>335.3 eggs/g feces) on farm A, and April, May and August (>304.3 eggs/g feces) on farm B. S. papillosus presented low FEC throughout the year on farm A, on farm B the highest values were obtained in April (303.0 eggs/g feces). Trichuris spp. presented maximum FEC values in May (328.6 eggs/g feces) on farm A and in June (157.5 eggs/g feces) on farm B. Treatment and age had significant influence on infection intensity of Strongylidae (farms A and B), S. papillosus (farms A and B) and Trichuris spp. (farm A). Rainfall had significant effect on S. papillosus (farms A and B) and Trichuris spp. (farm B). Maximum temperature showed significant effect on S. papillosus (farm A) and Trichuris spp. (farms A and B). Minimum temperature had significant influence on Strongylidae (farm A), S. papillosus (farms A and B) and Trichuris spp. (farm B). Haemonchus spp. (57%, 66%) and Cooperia spp. (30.0%, 30.7%) were the most prevalent genera identified by coproculture on both farms, in contrast, Trichostrongylus spp. and Oesophagostomum spp. were less frequent. Patent lungworm infections were low on both farms (10.8%, 1.8%). On farm A, high prevalence of antibodies against D. viviparus was determined only at the beginning of the study, in contrast, on farm B the seroprevalence fluctuated throughout the year. Treatment, age and maximum temperature had significant effect on D. viviparus counts on farm A, but not on farm B.

Evaluation of the transcription level of the protein disulfide isomerase in different stages from Ancylostoma caninum with a real-time PCR assay

The protein disulfide isomerase (PDI) is a ubiquitous protein, which contributes in building disulfide bridges. In the work presented here, the expression of the PDI in different stages of the canine hookworm Ancylostoma caninum was investigated. Third-stage larvae (L3), adults, as well as serum-stimulated and hypobiotic L3 were used. For quantification of the PDI gene transcription, a real-time PCR was used establishing a hybridization probe (TaqMantrade mark probes) for detection of PDI copy numbers in different populations. 18S ribosomal ribonucleic acid (rRNA) was used as a housekeeping gene for normalization. The results show differences in the transcription level of the investigated A. caninum populations: The serum-stimulated larvae representing the switch to parasitism showed the highest PDI expression. The hypobiotic larvae representing a resting stage showed the lowest expression level. Male adults showed an elevated expression compared to female adult worms. The L3 expression level was just below the serum-stimulated population. This work confirms the upregulated gene expression of PDI during host penetration and invasion.

Genetic regulation of arrested development in nematodes: are age-1 and daf-gene orthologs present in Dictyocaulus viviparus?

In opposite to the free-living soil nematode Caenorhabditis elegans, the genetic regulation of hypobiosis or inhibited or arrested development in parasitic nematodes is completely unknown. In C. elegans, the daf-genes or the age-1 gene are of major importance in signaling pathways regulating arrested development. To investigate if orthologs of these genes are present in the bovine lungworm Dictyocaulus viviparus, a PCR analysis with gene-specific primer combinations was performed. No orthologs of the age-1 or daf-genes could be identified in D. viviparus. The possible differences in the role of the daf-genes concerning arrested development in parasitic and free-living nematodes will be discussed.

Cases of reduced cyathostomin egg-reappearance period and failure of Parascaris equorum egg count reduction following ivermectin treatment as well as survey on pyrantel efficacy on German horse farms

In 2003 and 2004, on a total of 63 different German horse farms, a survey using the faecal egg count reduction (FECR) test was performed to investigate the efficacy of ivermectin (IVM, Ivomec) and pyrantel (PYR, Banminth) treatment against gastro-intestinal nematodes in a total of 767 horses. IVM treatment resulted in 100% reduction of the cyathostomin egg production 14 and 21 days post-treatment (d.p.t.) on 37 farms. On the remaining five farms, the mean faecal egg count reduction ranged between 97.7 and 99.9%. The mean cyathostomin FECR following PYR treatment ranged between 92.2 and 100% on the 25 farms tested. Therefore, based on the 90% FECR threshold suggested for detection of anthelmintic resistance in horses, neither IVM nor PYR anthelmintic resistance was detected. However, if the thresholds recommended for the detection of resistance in small ruminants were applied, on one and four farms signs of reduced IVM and PYR efficacy, respectively, were observed. In 2005, to further investigate these findings, the cyathostomin egg-reappearance period (ERP) following IVM treatment was examined on six selected farms, two of which were found to show less than 99.8% FECR in the previous survey. On these two latter farms, the ERP was less than 5 weeks, while on the other four it was at least 8 weeks. Earlier investigations described IVM cyathostomin ERP of at least 9 weeks. The efficacy of IVM to reduce Parascaris equorum egg excretion was also studied. On one farm in 2 consecutive years, IVM treatment did not lead to a significant reduction in P. equorum faecal egg counts in one and five young horses, respectively.

Differential gene expression in hypobiosis-induced and non-induced third-stage larvae of the bovine lungworm Dictyocaulus viviparus

Hypobiosis is of particular importance in overwintering of the bovine lungworm Dictyocaulus viviparus. However, in parasitic nematodes there is no information available on the genetic mechanisms of hypobiosis. Suppression subtractive hybridisation was performed to identify upregulated transcripts of hypobiosis-induced and non-induced third-stage D. viviparus larvae, respectively. Subtracted libraries containing 105 clones of the hypobiosis-induced and 104 clones of the non-induced larvae were generated. By differential screening and Southern dot blot, 26 clones of the hypobiosis-induced and 22 clones of the non-induced larvae were confirmed to be differentially expressed. Sequencing of rapid amplification of cDNA ends (RACE) and spliced-leader-1 PCR products was performed to further characterise selection of the differentially regulated gene transcripts. The genes encoding an N-methyltransferase and a superoxide dismutase were upregulated in the hypobiosis-induced and non-induced larvae, respectively. The expression patterns of these genes were validated by quantitative real-time PCR. This revealed differential gene expression, particularly for the N-methyltransferase.

Evaluation of a serological method for the detection of Taenia saginata cysticercosis using serum and meat juice samples

Two peptides, HP6-2 and Ts45S-10, were used as antigens for the detection of antibodies against Taenia saginata cysticercosis in serum and meat juice samples using enzyme-linked immunosorbent assay (ELISA). Positive control samples were obtained from animals experimentally infected (serum) and from animals naturally infected (meat juice). The two peptides and a pooled preparation of both peptides were evaluated, and their cut-off points with both sample categories were calculated. ELISA results from these different peptides were compared. Sensitivity and specificity of HP6-2 using serum were calculated as being 100 and 98%, respectively, showing to be higher than the values for the other antigens used. The average optical density (OD) value for negative samples was 0.646, whereas it was 1.702 for the positive control samples. This peptide was used to examine serum samples from animals with cysts and random field serum samples. For meat juice samples the pooled peptides showed the highest sensitivity and specificity, as they were 100 and 95%, respectively. The average OD values for the negative and the positive reference meat juice samples were 0.379 and 1.291, respectively. The optimal dilution of the meat juice samples for the ELISA was very low, as it was 1:20 using the pooled peptides, compared with 1:800 serum dilution using HP6-2. To the authors' knowledge, this is the first report of a successful testing for T. saginata cysticercosis using meat juice.