A 12-month study was conducted to assess and monitor gastrointestinal tract nematodes and liver fluke in cohorts of cattle on a Scottish organic dairy farm. Various diagnostic markers for helminth parasites of cattle from different age groups were assessed monthly from April 2007 to March 2008. First season grazing stock were subjected to significant challenge from Ostertagia ostertagi nematodes as reflected in serum pepsinogen concentrations, which rose markedly in the second half of the grazing season. In addition, plasma albumin concentrations decreased and faecal egg counts (FEC) increased moderately, indicating exposure to both O ostertagi and probably Cooperia oncophora. Second season grazing animals had a peak FEC early in the grazing period, suggestive of a potential carry-over of Ostertagia species infection ('Type 2') during housing. All classes of cattle showed evidence of fluke (Fasciola hepatica) infection. Adult cow exposure to O ostertagi and fluke was estimated via the use of ELISA testing to detect antibodies to O ostertagi and F hepatica and the high levels detected suggested a significant exposure response. Despite low stocking densities and sympathetic grazing management, there was a significant challenge to all grazing stock from gastrointestinal nematodes and liver fluke.

The objective of the present study was to determine the prevalence and associated determinants (e.g., sex, age, on-farm management and husbandry) of gastrointestinal (GI) helminths in the domestic animals of district Toba Tek Singh, Punjab, Pakistan. For this purpose, 1,140 cattle, 1,140 buffaloes, 660 goats, 840 sheep, and 156 camels were randomly selected and their fecal samples were screened every other week for a year using a modified floatation technique. The samples positive for strongyle-type eggs had the parasite species identified using coproculture. It was found that the prevalence of GI helminths was significantly higher (P < 0.05) in sheep (44.17%; 371/840) than in other livestock. Sheep were followed in order by goats (40.15%; 265/660), buffaloes (39.82%; 454/1,140), and cattle (33.68%; 384/1,140). The important helminth species identified were Fasciola (F.) gigantica, Fasciola hepatica, Haemonchus contortus, Toxocara vitulorum, Trichostrongylus spp., Oesophagostomum spp., Ostertagia spp., Cooperia spp., Strongyloides spp., Moniezia spp., and Trichuris spp. The prevalence of GI helminths except F. hepatica and F. gigantica was significantly higher in grazing animals, females (P < 0.05) and young (P < 0.05) of all the host species when compared with stall-fed animals, males and adults, respectively. Using ponds and rivers/canals as drinking water were found to have significant influence (P < 0.05) on the prevalence of GI helminths. The results provide a baseline data for planning future research and control strategies against GI helminthes.

The seroprevalence of Fasciola hepatica infection in a population of commercial dairy herds in England and Wales was estimated using an ELISA that detected antibodies to F hepatica in bulk tank milk. A total of 3130 milk samples, obtained as convenience samples from two commercial milk-testing laboratories, were tested during the winter of 2006/07. Herds considered to be seropositive were categorised as low positive, medium positive or high positive. A geospatial map was drawn to show the distribution of infected herds and the seroprevalence of exposure at regional level, using the Nomenclature of Units for Territorial Statistics boundaries, and at a finer spatial level defined by postcode area. Overall, 76 per cent (95 per cent confidence interval [CI] 74 to 77 per cent) of herds carried antibodies to F hepatica; the seroprevalence in England was 72 per cent (95 per cent CI 70 to 74 per cent) and in Wales it was 84 per cent (95 per cent CI 82 to 86 per cent). The highest prevalences of exposure were found in north-west England, where more than 47 per cent of herds were in the high positive exposure category.

Helminth infections are an important constraint on the health and development of poor children and adults. Anthelmintic treatment programmes provide a safe and effective response, and increasing numbers of people are benefitting from these public health initiatives. Despite decades of clinical experience with anthelmintics for the treatment of human infections, relatively little is known about their clinical pharmacology. All of the drugs were developed initially in response to the considerable market for veterinary anthelmintics in high- and middle-income countries. In contrast, the greatest burden caused by these infections in humans is in resource-poor settings and as a result there has been insufficient commercial incentive to support studies on how these drugs work in humans, and how they should best be used in control programmes. The advent of mass drug administration programmes for the control of schistosomiasis, lymphatic filariasis, onchocerciasis and soil-transmitted helminthiases in humans increases the urgency to better understand and better monitor drug resistance, and to broaden the currently very narrow range of available anthelmintics. This provides fresh impetus for developing a comprehensive research platform designed to improve our understanding of these important drugs, in order to bring the scientific knowledge base supporting their use to a standard equivalent to that of drugs commonly used in developed countries. Furthermore, a better understanding of their clinical pharmacology will enable improved therapy and could contribute to the discovery of new products.

A study was carried out to compare anti-Fasciola hepatica IgG levels in blood serum and mammary secretions during the entire lactation period in dairy cows experimentally infected with different numbers of F. hepatica metacercariae. The kinetics of specific antibodies passively transferred to the offspring was also studied. The MM3-SERO ELISA, a specific and sensitive method of detecting antibodies against F. hepatica, was used to detect antibodies in milk and serum samples. The progress of infection was monitored by use of the MM3-COPRO ELISA, an immunoassay for detecting Fasciola antigens in faecal samples. The optical density of serum and milk from uninfected control cows remained low throughout the study. In the infected animals, a similar pattern of anti-F. hepatica IgG kinetics was observed in serum and milk throughout the entire observation period. This IgG response was characterized by the early appearance of high levels of specific antibodies in serum (detectable 1-4 weeks pi) and in milk (detectable at the beginning of lactation) and remained invariably high throughout the entire lactation period in cows infected with low-to-moderate infective doses (>/=50 metacercariae). However, in animals administered very low infective doses (</=25 metacercariae) the levels of specific antibodies were variable, and would be difficult to interpret if only sporadic analyses were carried out. The MM3-SERO ELISA proved to be highly sensitive for use with milk samples, as it enabled detection of antibodies in cows infected with very low infective doses (</=25 metacercariae) and therefore harbouring very few flukes (probably<10). Moreover, specific antibodies were able to be detected at any stage of lactation, in milk from cows infected with >/=50 metacercariae, even when samples were diluted al least 1:8. In newborn calves fed colostrum from infected dams, the levels of anti-Fasciola antibodies increased rapidly, then decreased sharply and were no longer detected in calves >12 weeks old. The results indicate that the detection of antibodies in milk samples may provide useful information about the status of F. hepatica infection in dairy herds if repeated analyses are carried out. Analysis of bulk samples may also be an inexpensive way of identifying herds infected with F. hepatica, provided highly sensitive tests are used.

A surface plasmon resonance (SPR) biosensor screening assay was developed and validated to detect 11 benzimidazole carbamate (BZT) veterinary drug residues in milk. The polyclonal antibody used was raised in sheep against a methyl 5(6)-[(carboxypentyl)-thio]-2-benzimidazole carbamate protein conjugate. A sample preparation procedure was developed using a modified QuEChERS method. BZT residues were extracted from milk using liquid extraction/partition with a dispersive solid phase extraction clean-up step. The assay was validated in accordance with the performance criteria described in 2002/657/EC. The limit of detection of the assay was calculated from the analysis of 20 known negative milk samples to be 2.7mugkg(-1). The detection capability (CCbeta) of the assay was determined to be 5mugkg(-1) for 11 benzimidazole residues and the mean recovery of analytes was in the range 81-116%. A comparison was made between the SPR-biosensor and UPLC-MS/MS analyses of milk samples (n=26) taken from cows treated different benzimidazole products, demonstrating the SPR-biosensor assay to be fit for purpose.

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.

The objectives of this paper are to provide an introduction to meta-analysis and systematic review and to discuss the rationale for this type of research and other general considerations. We highlight methods used to produce a rigorous meta-analysis and discuss some aspects of interpretation of meta-analysis drawing on examples from the animal and veterinary science literature. Meta-analysis is a rapidly expanding area of research that has been relatively underutilized in animal and veterinary science. It is a quantitative, formal, epidemiological study design used to systematically assess previous research studies to derive conclusions about that body of research. Outcomes from a meta-analysis may include a more precise estimate of the effect of treatment or risk factor for disease, or other outcomes, than any individual study contributing to the pooled analysis. The examination of variability or heterogeneity in study results is also a critical outcome. The benefits of meta-analysis include a consolidated and quantitative review of a large, and often complex, sometimes apparently conflicting, body of literature. Meta-analytic methods place less emphasis on dichotomous outcomes from null hypothesis significance testing and greater emphasis on determining the magnitude and the precision of an effect of interest. A substantial benefit of meta-analysis is the potential to investigate new hypotheses using existing data, both through the development of a priori hypotheses and by examination of the heterogeneity in study responses. The specification of the outcome and hypotheses that are tested is critical to the conduct of meta-analyses, as is a sensitive literature search. A failure to identify the majority of existing studies can lead to erroneous conclusions; however, there are methods of examining data to identify the potential for studies to be missing; for example, by the use of funnel plots. Many of the statistical methods to conduct meta-analysis are widely used. Bayesian methods are well suited to meta-analysis. The post-hoc methods used to evaluate heterogeneity and publication bias, which include the I (2) statistic, L'Abbé plots, Galbraith plots, Rosenthal's N, and influential study analysis are exclusively used in meta-analysis. Examples where meta-analyses have been repeated in animal science or veterinary medicine show good consistency in estimates of effect. Findings of studies to date have provided new understandings of rumen modifiers, milk fever, parasite control, mastitis, somatotropin, and reproductive manipulations. Rigorously conducted meta-analyses are useful tools to improve animal well-being and productivity. The need to integrate findings from many studies ensures that meta-analytic research is desirable and the large body of research now generated makes the conduct of this research feasible.

Sheep meat production in France is characterized by large flocks and a limited supply of labour. Digestive-tract strongyles are considered as one of the main health problems and control relies mostly on the use of anthelminthics, although resistance to at least the benzimidazoles is increasing. We conducted interviews on nine conventional and seven organic farms regarding whether an anthelmintic targeted selective treatment program could fit within the operations of the farms. In addition, necropsies of lambs were performed on three organic farms, and faecal egg counts and small lungworm counts were performed on all farms in autumn in ewes. Each interview consisted of an open discussion on sheep health and was terminated with comments on digestive-tract helminth infection as detected in parallel with the interview. Factors likely to affect the adoption of the targeted selective treatment approach were subjected to cluster analysis. Conventional farms were mostly advised by veterinarians and relied on systematic planning of anthelmintic treatments. The frequency of treatments was up to once a month for lambs and two to three times a year for ewes. The concept of selecting animals to be treated according to a scheme of targeted selective treatments based on phenotypic markers (e.g., anaemia, diarrhoea, weight gains) was not seen as feasible by these farmers. Conversely, organic farmers, with greater use of advisors and a restricted range of anthelmintic treatments were more susceptible to integrating phenotypic markers into their practices for controlling digestive-tract strongyles.

The present study reports the prevalence, effects of treatment and cost benefit analysis of bovine fasciolosis in five districts of Punjab Province viz Sargodha, Jhang, Muzaffargarh, Lodhran and Layyah. From each of the five districts, 80 animals were selected and fortnightly screened through standard coprological procedures for a period of one year for the presence of eggs of Fasciola species. Of 4800 faecal samples analyzed, 1222 (25.46%) were found positive for fasciolosis. The occurrence of Fasciola (F.) gigantica (22.40%) was higher (P<0.05) than F. hepatica (3.06%). Highest month-wise prevalence (P<0.05) of fasciolosis was found in winter (39.08%) followed in decreasing order by spring (29.50%), autumn (20.33%) and summer (12.92%). District-wise prevalence of fasciolosis was highest (P<0.05) in Sargodha (40.31%) and lowest in Layyah (11.77%) while other districts were having intermediate values of prevalence of fasciolosis. Species-wise prevalence of fasciolosis was found higher (P<0.05) in buffaloes (30.50%) as compared to cattle (20.42%). However, there were no age and sex-related differences (P>0.05) in prevalence of fasciolosis. A strong positive association of grazing (OR=1.81), mixed farming of small and large ruminants (OR=1.39), stagnant pond bathing (OR=2.24) and river/canal bathing (OR=2.06) was found with the prevalence of fasciolosis as compared to stall feeding, separate farming of small and large ruminants and rivers/canal/tap water bathing, respectively. Post-treatment average milk increase of 0.62 L per animal per day with 0.35% higher fat was observed in fasciolicide-treated animals with the cost benefit ratio of 3.9. The results provided significant data on the epidemiology of five districts of Punjab province which may be helpful for the planners and small holder dairy farmers for control of fasciolosis in the study districts.

The present study aimed to obtain data on the occurrence of Giardia duodenalis in calves in four major cattle rearing countries in Europe (Germany, UK, France and Italy), along with genotyping data and risk factors associated with these infections. A total of 2072 calves were sampled on 207 farms. The majority of the animals were Holstein dairy or mixed Holstein calves (n=1565 or 75.5%), and were female (n=1640 or 79.1%). The average age was 7.8 weeks (SD=4.1; median=7; range=2-16 weeks). All fecal samples were tested using a commercially available monoclonal antibody-based ELISA. The overall apparent prevalence of G. duodenalis for the four countries was 45.4%(n=942/2072) and the overall farm prevalence was 89.9%(186/207), with differences in both animal and farm prevalence between the four countries. The prevalence was significantly higher in animals up to 8 weeks (OR=1.88; P<0.001) compared to older calves, and several management factors including contact with the Dam, Frequency of cleaning of the Maternity Pens, and Disinfection of the Calf Housing were found to be associated with infection. Positive samples were withheld for genotyping using the β-giardin and triose phosphate isomerase gene: G. duodenalis assemblage E was most prevalent, although 43% of the isolates were typed as assemblage A, with differences in between countries. Furthermore, 32% of the examined samples was found to be a mixed assemblage A and E infection, which is consistent with previous reports. The results of the present study confirm previous findings in other European countries that G. duodenalis infections are common in calves. The infection especially occurs in animals younger than 2 months, and the proportion of positive animals gradually decreased with increasing age.

The parasitic mite Psoroptes ovis causes important economic losses in Belgian Blue cattle. Because mange problems vary significantly between farms, a cross-sectional questionnaire survey and subsequent farm visits were performed to identify potential risk factors for P. ovis infections on Belgian Blue farms in Flanders, Belgium. The questionnaire was sent to 1800 beef farms to evaluate the presence and severity of psoroptic mange in the herd and to assess farm management practices, including antiparasitic treatments. Subsequently, about 10% of the farms with a completed questionnaire were visited to validate the questionnaire and to retrieve supplementary information on additional management parameters, such as barn infrastructure and climate. Associations between parasitism and putative risk factors were assessed by logistic regression. Out of 1800 contacted farms, 680 (38%) completed questionnaires were received. Data were collected from 238 barns during 66 farm visits. The questionnaire results demonstrated a high farm prevalence of mange (74%; 95% CI (70.7-77.3)) and half of the farmers declared that the problem was difficult to control. Nevertheless, in only 14% of the barns a high scratching index was recorded and in most of the sampled animals (80%) the affected body surface was less than 10%. This indicates that despite the high prevalence and the difficulty to control the infection, clinical signs were often quite moderate. Logistic regression analyses of the questionnaire and the farm visit data suggested that heavily infested farms treat more intensively against mange. On most farms mange occurred the whole year round and more problems with mange were found on farms where a higher number of animals were purchased per year. In addition, the disease was more prevalent when the animals had a lower hygiene score. This score was strongly correlated with environmental hygiene, indicating that transmission of mites from the environment to the animals should not be underestimated. Conflicting results were obtained on the effect of supplementing minerals on the occurrence of mange. In this study, temperature, light intensity and relative humidity in the barns, ventilation systems, barn infrastructure, animal stocking rate and blood mineral levels were not indicated as risk factors for mange. In conclusion, maintaining a good animal hygiene and if possible, avoiding introduction of cattle may help to control psoroptic mange in Belgian Blue cattle.

The main objective of the present study was to evaluate the accuracy of the faecal egg count reduction test (FECRT) to assess the resistance status of ivermectin (IVM)-resistant isolates of the cattle nematodes Ostertagia ostertagi and Cooperia oncophora, using the controlled efficacy test (worm counts) as a reference. The second objective was to investigate whether both IVM-resistant isolates showed side-resistance against moxidectin (MOX) under controlled conditions. Thirty male Holstein calves were experimentally infected with 25,000 L3 of an IVM-resistant O. ostertagi isolate and 25,000 L3 of an IVM-resistant C. oncophora isolate. Twenty-eight days later the calves were randomly divided into 2 treatment groups and 1 untreated control group. Animals in groups 1 and 2 received MOX (Cydectin(®) 1%, Pfizer) and IVM (Ivomec(®) 1%, Merial) respectively, by subcutaneous injection at a dose rate of 0.2mg/kg bodyweight. Faecal samples were collected 7 and 14days after treatment and animals were necropsied 14/15days post-treatment. Both the FECRT and the controlled efficacy test demonstrated that the O. ostertagi and C. oncophora isolates were resistant against IVM, with efficacies below 90%. The IVM-resistant O. ostertagia isolate was still susceptible to MOX treatment, as shown by over 99% reduction in egg counts and worm burden. The FECRT suggested borderline resistance against MOX in the IVM-resistant C. oncophora isolate, with egg count reductions between 97%(95% CI: 76; 100) at day 7 and 86%(95% CI: 49; 96) at day 14. However, the controlled efficacy test clearly showed MOX-resistance, with a decrease of only 31%(95% CI:-12; 57) in C. oncophora worm numbers. After MOX treatment, a significantly lower number of eggs per female C. oncophora worms was counted compared to the control group (43% reduction). Due to this reduced fecundity, the FECRT may fail to detect MOX-resistance.

Parasitism by gastrointestinal nematodes is a health concern in New World Camelids (NWC) worldwide, and anthelmintic treatment is often needed for parasite control. Although anthelmintic resistance has been reported in ruminants worldwide, data in NWC are only scarce. In the present study, a case of suspected doramectin resistance in alpacas was examined. A field efficacy study was conducted for the evaluation of two different dosages of doramectin using a faecal egg count reduction test. A group of 8 alpacas was treated with a subcutaneous injection of doramectin at 0.2mg/kg bodyweight. Individual faecal samples were collected before treatment and 7 days after treatment. The faecal egg counts indicated a treatment efficacy of only 68%. To determine whether the treatment failure was caused by true anthelmintic resistance or suboptimal dosage in this animal species, a group of 4 alpacas was subsequently treated at 0.3mg/kg bodyweight. Faecal egg counts 7 days post treatment were reduced by only 41%, indicating that the treatment failure was more likely to be caused by the presence of resistant parasites on this farm. Coprocultures of faecal samples collected after treatment indicated the presence of 98.5% Haemonchus contortus and a small percentage of Cooperia oncophora (<1.5%). A controlled efficacy trial in sheep, for which the optimal dosage of doramectin is known, was conducted to ensure that this truly was a case of resistant parasites. Infective larvae collected from the faeces of these alpacas were used to infect eight nematode-free lambs. These lambs were assigned to one of two groups based on faecal egg counts post infection. One group was treated with doramectin injectable at 0.2mg/kg bodyweight, the other group served as a non treated control group. Pharmacokinetics indicated that the doramectin treatment was adequate, yet an efficacy of only 16% was determined on day 7 after treatment. Identification of the larvae after treatment revealed 100% H. contortus. On day 7 after treatment, H. contortus worm counts were only reduced by 8% in the treated lambs. The results of the present study report for the first time a case of doramectin resistance in alpacas, mainly in H. contortus.

Giardia duodenalis is a protozoan parasite known to infect animals and humans. Zoonotic transmission of G. duodenalis can occur by the consumption of drinking water produced from surface water that is contaminated by runoff from manure-laden fields or pastures. Although it was previously reported that storing solid cattle manure decreases G. duodenalis cyst viability, no data are available on cyst survival in slurry waste from cattle. In this study the number and the viability of G. duodenalis cysts was determined in cattle slurry for up to 90 days. G. duodenalis cysts were counted in 30 slurry samples with a quantitative direct immunofluorescence assay. The geometric mean number of cysts was reduced by 77% after 90 days (P<0.0014), although there was substantial variability between samples. A fluorogenic dye staining using 4',6'-di-amino-2-phenylindole and propidium iodide showed a decreased viability from 45 days onwards, and after 90 days incubation, only 3% of the cysts were viable. Gerbils and lambs were artificially infected with 50 day-old and 90 day-old cysts and faecal excretion of G. duodenalis was monitored between 5 and 7 days after infection. Seven days after infection the gerbils were euthanized for Giardia trophozoite counts. Although one cyst was found in the faeces of one of the gerbils after infection with 50 day-old cysts, no trophozoites were recovered from the intestines of any gerbil (n=8). Experimental infection of lambs with 10(5)50 day-old and 90 day-old slurry cysts caused low cyst excretion in one out of two and one out of three lambs, respectively. Together, these data show that storage of cattle slurry for 90 days greatly reduces the number and viability of G. duodenalis cysts.

Ivermectin (IVM) resistance is an emerging problem for the control of gastrointestinal nematodes of cattle such as Cooperia oncophora and Ostertagia ostertagi. Although there is still a poor understanding of the molecular basis of macrocyclic lactone (ML)-resistance, it is clear that IVM exerts its activity by binding to glutamate-gated chloride (GluCl) channels within the parasite's neuromuscular system. One of the GluCl genes (avr-14) encodes, via alternative splicing, two subunits, AVR-14A and AVR-14B; the latter is suggested to be the main target for IVM. The genomic DNA (gDNA) sequence of avr-14 in C. oncophora contains 21 exons separated by 20 introns and spans approximately 10 kb of gDNA. Intron 13 contains a sequence with high homology to a mammalian mariner transposase. The L256F polymorphism in the avr-14 gene, which was shown to be associated with IVM resistance in a UK isolate of C. oncophora, was not found in the IVM-resistant C. oncophora and O. ostertagi isolates investigated in this study. However, genetic analyses on C. oncophora indicated a loss in allelic diversity of the avr-14 gene in the resistant isolates compared with the susceptible isolate. This suggests that the avr-14 gene, or another genetically linked locus, is under selection in these Belgian C. oncophora isolates. Comparison of the full-length avr-14B coding sequence in the susceptible and resistant C. oncophora isolates did not show any polymorphisms specifically linked to IVM resistance, although a decrease in the number of avr-14B isoforms was observed in the resistant isolates compared with the susceptible one. Measuring the transcription levels of avr-14B in adult male and female C. oncophora and O. ostertagi worms showed significantly lower levels in resistant worms compared with susceptible ones. Whether the down-regulation of this IVM target actually contributes to the resistance mechanism in these worms remains unclear.

In this study we have used the faecal egg count reduction test (FECRT) to monitor the evolution of ivermectin resistance on a Belgian cattle farm between 2006 and 2009. The presence of ivermectin resistant Cooperia oncophora worms on this farm was first detected in 2006. During the following years, the FECRs on day 21 post-treatment decreased from 73%(95% CI: 8-99) in 2006, over 40%(95% CI: 0-89) in 2007, to 0%(95% CI: 0-41) in 2008. The ivermectin resistant C. oncophora showed side-resistance against moxidectin, indicated by a FECR of 83%, suggesting that the use of any type of ML is discouraged once ivermectin resistance has been detected. Benzimidazoles on the other hand were still fully effective on this farm. The resistant C. oncophora larvae collected in 2007 (CoIVR07) and 2008 (CoIVR08) were also used to evaluate a modified version of the larval migration inhibition assay (LMIA). The results indicated that it is possible with the LMIA to differentiate susceptible from ivermectin resistant C. oncophora isolates. The EC(50) values of CoIVR07 (542nM) and CoIVR08 (698nM) were, respectively, 4.5- and 5.8-fold higher than the value of a susceptible isolate (120nM). Furthermore, the results of the LMIA reflected the outcome of the FECRT, with the C. oncophora isolate collected in 2008 being more resistant than the isolate collected in 2007. However, the test should be further optimized, e.g. more isolates with different susceptibility to ivermectin and mixtures of species, in order to use the test in field conditions.

Anthelmintic resistant cattle nematodes have been reported in different regions around the world. However, in Western Europe the assessment of the problem relies largely on case reports and no prevalence data based on wide-scale surveys are available. Therefore, we performed a survey to (1) screen for reduced anthelmintic efficacy in Belgian and German cattle farms;(2) evaluate the usefulness of a simplified faecal egg count reduction test (FECRT), where efficacies are based on the mean FECs of 10 at random collected faecal samples pre- and post-treatment per farm and (3) identify possible risk factors for reduced anthelmintic efficacy. Of 88 farms included in this study, 84 farms used macrocyclic lactones (MLs). A FECR <95% was observed on 39% of these 84 farms. However, using a Markov chain Monte Carlo simulation analysis, to correct for the used McMaster FEC technique with a detection limit of 50epg, reduced efficacy could only be confirmed in 25% of the farms (21/84). Only Cooperia spp. were found in significant numbers in the coprocultures post-treatment. Reduced efficacy was significantly associated with farm type and with a lower efficacy in beef herds compared to dairy herds. Four farms were revisited and a standardized FECRT was performed to confirm anthelmintic resistance (AR). Surprisingly, macrocyclic lactone resistance against Cooperia oncophora was only confirmed in one of four farms. In conclusion, our results show that a reduced efficacy observed in a FECRT are not only caused by AR but that the detection limit of the FEC technique used and the (in)correct administration of the anthelmintic drugs are confounding factors of major importance.

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.

SUMMARYStool samples from Belgian patients suffering from abdominal pain and/or diarrhoea were examined for Cryptosporidium and Giardia. Cryptosporidium-positive samples were genotyped using the 70 kDa heat shock protein and the 60 kDa glycoprotein (GP60) genes: C. hominis was identified in 54.2% and C. parvum in 45.8% of the samples. Sequencing at the GP60 locus indicated that subgenotype IbA10G2 of C. hominis and subgenotype IIaA15G2R1 of C. parvum were the most prevalent, although several other subgenotypes were identified. For Giardia, sequencing at the beta-giardin, triose phosphate isomerase (TPI) and glutamate dehydrogenase (GDH) genes revealed assemblage B as the most prevalent (74.4%) in human patients. A high degree of heterogeneity was found, especially on the beta-giardin gene, and to a lesser extent on the GDH gene. Furthermore, using a novel species-specific PCR based on the TPI gene, mixed infections with both assemblage A and B were detected in a large number (32.4%) of human patients, which might have important epidemiological implications.

Liver flukes of animals are parasitic flatworms (Platyhelminthes: Digenea) of major socioeconomic importance in many countries. Key representatives, such as Fasciola hepatica and F. gigantica, cause "liver fluke disease"(= fascioliasis), which is of major animal health significance worldwide. In particular, F. hepatica is a leading cause of production losses to the livestock (mainly sheep and cattle) and meat industries due to clinical disease, reduced weight gain and milk production, and deaths. This parasite is also a major food-borne pathogen of humans throughout parts of the Middle East, Asia and South America. Currently, there is a significant focus on the development of new approaches for the prevention and control of fascioliasis in livestock. Recent technological advances in genomics and bioinformatics provide unique opportunities for the identification and prevalidation of drug targets and vaccines through a better understanding of the biology of F. hepatica and related species as well as their relationship with their hosts at the molecular level. Surprisingly, despite the widespread socioeconomic impact of fascioliasis, genomic datasets for F. hepatica are scant, limiting the molecular biological research of this parasite. The present article explores specifically the transcriptome of the adult stage of F. hepatica using an integrated genomic-bioinformatic platform. The analysis of the current data reveals numerous molecules of biological relevance, some of which are inferred to be involved in key biological processes or pathways that could serve as targets for new trematocidal drugs or vaccines. Improved insights into the transcriptome of F. hepatica should pave the way for future, comparative analysis of the transcriptomes of other developmental stages of this and related parasites, such as F. gigantica, cancer-causing flatworms (Clonorchis sinensis and Opisthorchis viverrini) and blood flukes (Schistosoma mansoni and S. japonicum). Prediction of the essentiality of genes and their products, molecular network connectivity of trematode genes as well as experimental exploration of function should also add value to the genomic discovery efforts in the future, focused on biotechnological outcomes.

A retrospective study was carried out to assess the possibility of using daily weight gain in first-season grazing cattle (FSG) as a marker for treatment decisions to prevent parasite-induced losses caused by gastrointestinal (GI) nematodes. This is intended as a proof of concept for using targeted selective treatments (TSTs) in the control of veterinary parasites. Historical data were combined from three independent grazing trials in Sweden, each of which was repeated over 2-3 years, in order to investigate the influences of parasites on the performance of FSG cattle subjected to different levels of parasite control. In general, the different trials and years produced congruent results. There was a good positive linear relationship between daily weight gains (Dwgt) registered around housing and those recorded in the middle of the grazing season (r(2)=0.54) but not between early-season Dwgt and housing Dwgt. The latter observation emphasizes that factors other than nematode infection influence the final weight of the cattle. However, significant differences in Dwgt ( approximately 0.2kg/day) were also observed depending on the nematode-control level achieved. At selected time points, the mean number of trichostrongylid eggs, serum pepsinogen concentration and Ostertagia antibody levels were significantly higher in animals with poor performance. ROC analyses showed that anthelmintic treatment of animals with a Dwgt of <0.75kg/day by mid-season had a sensitivity of approximately 70% and a specificity of approximately 50%. It thus seems feasible to base a targeted selective treatment for FSG cattle on Dwgt recorded approximately 4-8 weeks after turn-out, provided that it is accepted that some animals will be dewormed without indication. This now needs to be tested in controlled field trials.

T helper (Th) cells produce signature cytokine patterns, induced largely by intracellular versus extracellular pathogens that provide the cellular and molecular basis for counter regulatory expression of protective immunity during concurrent infections. The production of IL-12 and IFN-gamma, for example, resulting from exposure to many bacterial, viral, and protozoan pathogens is responsible for Th1-derived protective responses that also can inhibit development of Th2-cells expressing IL-4-dependent immunity to extracellular helminth parasites and vice versa. In a similar manner, concurrent helminth infection alters optimal vaccine-induced responses in humans and livestock; however, the consequences of this condition have not been adequately studied especially in the context of a challenge infection following vaccination. Demands for new and effective vaccines to control chronic and emerging diseases, and the need for rapid deployment of vaccines for bio security concerns requires a systematic evaluation of confounding factors that limit vaccine efficacy. One common albeit overlooked confounder is the presence of gastrointestinal nematode parasites in populations of humans and livestock targeted for vaccination. This is particularly important in areas of the world were helminth infections are prevalent, but the interplay between parasites and emerging diseases that can be transmitted worldwide make this a global issue. In addition, it is not clear if the epidemic in allergic disease in industrialized countries substitutes for geohelminth infection to interfere with effective vaccination regimens. This presentation will focus on recent vaccination studies in mice experimentally infected with Heligmosomoides polygyrus to model the condition of gastrointestinal parasite infestation in mammalian populations targeted for vaccination. In addition, a large animal vaccination and challenge model against Mycoplasma hyopneumonia in swine exposed to Ascaris suum will provide a specific example of the need for further work in this area, and for controlled field studies to assess the impact of other similar scenarios.

The interest in novel methods of controlling helminth infections in ruminants is driven primarily by the development of parasite resistance to currently available anthelmintics. While the purpose of anthelmintics is to achieve high efficacy, i.e.>90% reduction of adult and/or larval parasites in the target host animal, the purpose of novel parasite control methods is rather to assist in maintaining parasite infections below the economic threshold. The ability to maintain parasite levels below the economic threshold is related not only to the efficacy of the control method, but also to the epidemiology of the parasites, climatic conditions, the livestock management program, and integration in a sustainable parasite control program. Because of this fundamental difference, novel parasite control methods need to be evaluated using efficacy criteria different from that adopted for anthelmintics. Although the efficacy of novel parasite control methods may be demonstrated in classic dose-confirmation studies, the impact on livestock production parameters can only be evaluated when tested on-farm. In this paper, the rationale for evaluating novel methods differently from anthelmintics is reviewed, potential performance expectations are presented, and four novel parasite control methods (vaccines, nematophagous fungi, condensed tannins, and immunonutrition) are assessed based on the potential performance criteria.

The virtual reliance on anthelmintic drugs alone to control internal parasites of livestock is inappropriate and ultimately unsustainable. In the tropics and subtropics, widespread and high levels of anthelmintic resistance, particularly in nematode parasites of small ruminants, is rife. But more to the point, many farmers in these regions of the world are resource poor and cannot afford, or are reluctant to purchase drugs that may also be of dubious quality. As it is with any intervention, the benefits must outweigh the costs. This is not only in terms of conventional parameters such as reduced mortality and increasing productivity (meat, milk, fibre and traction power) of livestock, but also within the broad framework of helminths of veterinary/human importance, the aim should be a positive impact on reducing the threat of helminth zoonoses. However, understanding the issues involved and education of the end-users (farmers) is of fundamental importance, before any internal parasite control program should be promoted. Within the above context, we provide examples of how the "basket of options" approach could be adopted for the control of three quite disparate helminth problems in the tropics and subtropics, viz.: strongyle nematode infections of donkeys, the Taenia solium cysticercosis/taeniosis problem of pig and man and Haemonchus contortus infections in small ruminants. The "best practice" approaches can be defined as those "basket of options" that are practical, affordable, available and appropriate, whether to the commercial producer, or to the resource-poor farmer. Constraints that may restrict applying such options are accessibility to, and affordability of, suitable remedies and above all, the availability of information needed to make informed decisions in this regard.

Helminth infections are a major cause for reduced productivity in livestock, particularly those owned by the poor worldwide. Phytomedicine has been used for eons by farmers and traditional healers to treat parasitism and improve performance of livestock, and many modern commercial medicines are derived from plants. However, scientific evidence on the anti-parasitic efficacy of most plant products is limited, regardless of their wide ethnoveterinary usage. Scientific validation of the anti-parasitic effects and possible side-effects of plant products in ruminants is necessary prior to their adoption as a novel method for parasite control. A variety of methods has been explored to validate the anthelmintic properties of such plant remedies, both in vivo and in vitro. In vitro assays are useful as pre-screens of activity and are mainly performed with the free-living rather than parasitic stages of nematodes. Concentrations of potentially active substances used in vitro do not always correspond to in vivo bioavailability. Therefore, in vitro assays should always be accompanied by in vivo studies when used to validate the anthelmintic properties of plant remedies. In vivo controlled studies have shown that plant remedies have in most instances resulted in reductions in the level of parasitism much lower than those observed with anthelmintic drugs. Whether it is necessary or not to achieve very high efficacy in order for plant remedies to have a role in the control of parasitism depends on the determination of biologically important levels of reduction of parasitism and it will be required prior to the wide-scale use of plant products for parasite control. Similarly, standardisation of validation studies in reference to the numbers of animals required for in vivo studies to measure direct anthelmintic effects of a plant needs to be established. Although in many cases the active compounds in the herbal remedies have not been fully identified, plant enzymes, such as cysteine proteinases, or secondary metabolites, such as alkaloids, glycosides and tannins have shown dose-dependent anti-parasitic properties. However, as some of the active compounds may also have anti-nutritional effects, such as reduced food intake and performance, it is essential to validate the anti-parasitic effects of plant products in relation to their potential anti-nutritional and other side effects. A concerted effort on isolation, development, and validation of the effects of these herbal remedies will have to be undertaken before their wider acceptance.

Gastrointestinal nematode parasitism is arguably the most serious constraint affecting sheep production worldwide. Economic losses are caused by decreased production, the costs of prophylaxis and treatment, and the death of the infected animals. The nematode of particular concern is Haemonchus contortus, which can cause severe blood loss resulting in anemia, anorexia, depression, loss of condition, and eventual death. The control of nematode parasites traditionally relies on anthelmintic treatment. The evolution of anthelmintic resistance in nematode populations threatens the success of drug treatment programs. Alternative strategies for control of nematode infections are being developed, and one approach is to take advantage of the host's natural or acquired immune responses, which can be used in selection programs to increase the level of resistance in the population. Vaccination can also be used to stimulate or boost the host's acquired immunity. The induction of protective resistance is dependent on the pattern of cytokine gene expression induced during infection by two defined CD4+ T-helper cell subsets, which have been designated as Th1 or Th2. Intracellular parasites most often invoke a Th1-type response, and helminth parasites a Th2-type response. Breeds of sheep resistant to infection have developed resistance over a much longer term of host-parasite relationship than genetically selected resistant lines. The immune components involved in these different responses and types of host-parasite relationships will be reviewed. The potential for using vaccines has been investigated, with variable results, for several decades. The few successes and potential new antigen candidates will also be reviewed.

Parasites are linked with their host in a trophic interaction with implications for both hosts and parasites. Interaction stretches from the host's immune response to the structuring of communities and the evolution of biodiversity. As in many species sex determines life history strategy, response to parasites may be sex-specific. Males of vertebrate species tend to exhibit higher rates of parasites than females. Sex-associated hormones may influence immunocompetence and are hypothesised to lead to this bias. In a field study, we tested the prediction of male biased parasitism (MBP) in free ranging chamois (Rupicapra rupicapra rupicapra), which are infested intensely by gastrointestinal and lung helminths. We further investigated sex differences in faecal androgen (testosterone and epiandrosterone), cortisol and oestrogen metabolites using enzyme immunoassays (EIA) to evaluate the impact of these hormones on sex dependent parasite susceptibility. Non-invasive methods were used and the study was conducted throughout a year to detect seasonal patterns. Hormone levels and parasite counts varied significantly throughout the year. Male chamois had a higher output of gastrointestinal eggs and lungworm larvae when compared to females. The hypothesis of MBP originating in sex related hormone levels was confirmed for the elevated output of lungworm larvae, but not for the gastrointestinal nematodes. The faecal output of lungworm larvae was significantly correlated with androgen and cortisol metabolite levels. Our study shows that sex differences in steroid levels play an important role to explain MBP, although they alone cannot fully explain the phenomenon.

A general review of the epidemiology, significance and control of nematode parasitism of sheep, goats, cattle and deer in New Zealand, the emergence of anthelmintic resistance and its effects, and the search for parasite control strategies that reduce reliance on anthelmintic use, is provided. The research that has formed the basis for present levels of understanding of this complex and important topic is summarised and sources of further information are indicated. Aspects of nematode infections of horses, pigs, dogs and cats, and the history of the liver fluke, Fasciola hepatica, in New Zealand are also reviewed briefly.

AIMS To determine whether: a) using a controlled-release anthelmintic capsule (CRC) instead of a programme of 5 oral drenches administered at 3-4 week intervals, would delay the development of anti-parasite immunity in lambs; b) the use of ivermectin instead of albendazole, administered either as a CRC or as a programme of 5 oral drenches, would delay the development of anti-parasite immunity in lambs; c) lambs treated with CRCs would have higher liveweight gains than lambs drenched orally 5 times at 3-4 week intervals, and; d) delayed onset of anti-parasite immunity is associated with reduced liveweight gains in the period following anthelmintic treatment. METHODS Three field trials were conducted, 1 on a research farm and 2 on commercial sheep farms, in which groups of 30 lambs were treated with either a CRC containing albendazole, a CRC containing ivermectin, 5 oral drenches with albendazole, or 5 oral drenches with ivermectin, administered at 3-4 week intervals. Liveweights and faecal nematode egg counts (FECs) were recorded in all trials. Immunoglobulin-G (IgG) antibody levels to Ostertagia circumcincta and Trichostrongylus colubriformis adult and larval antigens were measured in Trials 1 and 3, and fleece weights and resistance of animals to nematode challenge infection were measured in Trial 1. RESULTS CRC-treated lambs had higher levels of antibodies to O. circumcincta infective-stage larvae (L3) than orally drenched lambs in Trial 3, but no other immunological differences due to mechanism of delivery were detected. Antibody levels were lower in lambs treated with ivermectin than albendazole, as a CRC or oral drench in Trial 1, but this was not associated with any measurable effects on FEC or productivity. No significant differences (p>0.05) were detected between drench types (albendazole vs ivermectin) or delivery mechanisms (CRC vs oral drenching) in any of the production parameters measured, in any of the trials. Albendazole-CRCs failed to control FECs in all 3 trials. CONCLUSIONS Although some differences between treatments in antibody levels were detected these were not associated with measurable differences in level of parasitism or productivity of lambs. CRC use did not appear to offer substantial gains in productivity over a structured programme of 5 oral drenches administered at 3-4 week intervals.