The efficacy of four anthelmintics against Calicophoron daubneyi in naturally infected dairy cattle.

The paramphistomicidal activity of four anthelmintics in dairy cattle naturally infected by Calicophoron (Paramphistomum) daubneyi was evaluated. Seventy Friesian adult cows were treated at drying-off (19 albendazole; 23 netobimin; 13 closantel and 15 oxyclozanide), and 21 remained untreated as controls. The anthelmintic efficacy was determined by estimating the faecal egg count reduction (FECR) values for each of the anthelmintics. The reduction in the number of cows shedding eggs in the faeces was also estimated. The C. daubneyi egg-output was not fully suppressed following the administration of any of the parasiticides. The FECR values ranged from 0% to 26% in the cows receiving albendazole or netobimin, with 11-39% of cattle becoming negative after therapy. Better results were achieved with closantel and oxyclozanide, with FECR values of 97-99% and CPCR (cattle positive by coprology reduction) percentages of 85-93%. The observation of a similar efficacy with closantel and oxyclozanide against C. daubneyi led us to recommend the administration of closantel in those countries where oxyclozanide is not available.

Ability of the fungus Duddingtonia flagrans to adapt to the cyathostomin egg-output by spreading chlamydospores.

The analysis of the capability of the nematode trapping-fungus Duddingtonia flagrans to adapt to the cyathostomin egg-output in horses was evaluated. Fecal samples from 196 pasturing autochthonous Pura Raza Galega horses were collected from the rectum and then divided according to the egg-output into three groups: ≤ 300, 310-800 and >800 eggs per gram feces. Four doses of chlamydospores (0.1, 0.2, 0.4 and 0.8 × 10(6)/100g feces) were directly spread onto fecal pats on the ground, remaining one without treatment as control. Fecal pats confirmed the presence of gastrointestinal nematode larvae belonging to strongylid cyathostomins (Cyathostomum and Gyalocephalus spp). An overall 94% (95% CI 91, 97) percentage of reduction was obtained, and an increase in the activity of the trapping-fungi simultaneously to the rising in the number of cyathostomin eggs and larvae in the coprocultures was detected. A significantly highest reduction of the cyathostomin L3 in the coprocultures with more than 800 EPG was found, which indicates that Df trapping activity is larvae nematode density-dependant. The present research showed the high biological activity of D. flagrans against nematode larvae can adjust to the cyathostomin egg-output, and underlines its efficacy as a practical method for the control of these parasites in grazing horses.

A novel second instar Gasterophilus excretory/secretory antigen-based ELISA for the diagnosis of gasterophilosis in grazing horses.

We have developed a novel enzyme-linked immunosorbent assay (ELISA) based on excretory/secretory antigens of second instar Gasterophilus for the diagnosis of gasterophilosis in grazing horses. Between January 2007 and January 2009, two experiments were carried out on free-ranging horses in northwest Spain. During the first year, monthly blood samples were collected from a herd of 25 horses. In the second year, a monthly serological survey was conducted for a total of 398 different horses. All the sera were analyzed by ELISA using excretory/secretory antigens from Gasterophilus intestinalis (GphiL2ES) and Gasterophilus nasalis second-stage larvae (GphnL2ES). Climatic data were collected between January 2007 and January 2009 from local meteorological automated stations to establish the weather pattern in the study area. Observations of Gasterophilus eggs on the horses' hair and third instars passed in the faeces were also done. The kinetics of IgG response decreased against GphiL2ES from January to July, increased slowly from August and rose up to January. After a slight decrease in January, the absorbances against GphnL2ES reduced from April to August, when the lowest values were observed. The IgG values rose until the end of the study in January. Third instars were observed in the faeces in March to May, and Gasterophilus eggs were seen on the horses' hair from June to September. The highest IgG seroprevalences were achieved in winter (January-February; 100%) against both antigens. The lowest percentages of seropositivity were observed in June (3%) to the GphiL2ES, and in July (9%) to the GphnL2ES. The use of antigens from G. intestinalis second-stage larvae was shown to be suitable for diagnosing infestation by G. intestinalis or G. nasalis. We concluded that under oceanic climate conditions, the egg-laying period occurs from late spring, and eggs and first instars are found in the mouth in early summer. During summer the second instars move into the stomach and intestine, where the third-stage larvae remain until the end of winter, when pupation takes place. The adult horse bot fly emerges in the spring. Two treatments for the control of gasterophilosis are suggested: a curative in the summer to eliminate the first instars and a preventive in the autumn to suppress the second instars.

Application of the analysis of serum antibodies (immunoglobulins M and G) to estimate the seroprevalence of ovine oestrosis and to evaluate the effect of chemotherapy.

The analysis of immunoglobulin (Ig) M and IgG serum isotypes as indicators of the presence of Oestrus ovis developmental stages was carried out. A serological survey to discover the seasonal variations in the prevalence of oestrosis in sheep from an oceanic climate area was developed. Six hundred and sixty-nine blood samples were analyzed for the presence of IgM and IgG using an enzyme-linked immunosorbent assay and O. ovis second-stage larvae excretory/secretory antigens. In addition, the effect of an ivermectin-based treatment on the humoral immune response was measured. The percentage of positive animals was 54% for IgM and 55% for IgG. The highest percentages of sheep positive to IgM were recorded in the winter and to IgG in the summer. No animals positive to IgM were detected in the ivermectin-treated sheep. These results seem to underline that oestrosis is a parasitic disease to keep watch for in regions with an oceanic climate. A noninvasive evaluation of the success of chemotherapy seems possible by analyzing the serum IgM response.

An approach of the laboratory to the field: assessment of the influence of cattle management on the seroprevalence of fascioliasis by using polyclonal- and recombinant-based ELISAs.

A cross-sectional study was conducted to assess the seroprevalence of fascioliasis by immunoenzymatic probes in an endemic area (northwestern Spain). Blood samples were collected from 1,034 cattle (crossbred, Rubia Gallega, and Friesian breeds), and the diagnosis of fascioliasis was carried out by determining both the occurrence of antigenemia and the presence of specific IgG antibodies against a Fasciola hepatica recombinant protein (FhrAPS). The IgG seroprevalence was 65% (95% CI, 62-68) by the FhrAPS-ELISA, and 32% (29-35) exhibited antigenemia; the lowest percentages occurred in the Friesians, and the highest percentages were found in the crossbreds. These results confirm an elevated seroprevalence of fascioliasis that is unexpected considering that most of the cattle livestock (Friesian and Rubia Gallega) receive fasciolicide treatment. The lack of adequate measures on the environment and erratic chemotherapy seem to be responsible for the fact that control of fascioliasis has not improved in the last 10 yr in the area of study.

Clinical trial of efficacy of ivermectin pour-on against gastrointestinal parasitic nematodes in silvopasturing horses.

The aim of this study was to assess, by a clinical trial, the efficacy of an ivermectin-based pour-on treatment against gastrointestinal parasitic nematodes in naturally infected horses using 2 groups of mature indigenous Pura Raza Galega grazing mares. Faecal and blood samples were collected individually over a 21 week period. Faeces were analysed by the coprological flotation, sedimentation and migration techniques. Changes in circulating blood cells were monitored over the study period. The administration of the ivermectin suppressed the egg-elimination of ascarids and pinworms throughout the study and no strongyle-eggs were observed in the treatment group between the 3rd and 10th weeks. The numbers of red cells increased significantly after the anthelmintic therapy, and a statistical reduction in circulating leucocytes was recorded. No side effects were observed. The pour-on ivermectin formulation was highly successful against gastrointestinal nematodes and appears to be a useful therapeutic routine for large groups of horses.

Silvopastoralism and autochthonous equine livestock: analysis of the infection by endoparasites.

Two groups of autochthonous Pura Raza Galega (PRG) horses, one comprising 483 animals under a silvopasturing regime, and the other comprising 72 PRG horses managed in farms, were used to analyse the effect of silvopasture on infection by endoparasites. Results were considered according to the age and the sex of the horses. Faecal samples were individually collected from each animal and analysed by the coprological flotation, sedimentation and migration techniques. Coprocultures were also done to identify the main strongylid genera affecting the horses. Eggs from the gastrointestinal nematoda Parascaris equorum, strongyles and Oxyuris equi were the only endoparasites observed in the faeces of the horses. Larvae of Trichonema and Cyalocephalus spp. (small strongyles) and Strongylus and Triodontophorus (large strongyles) were identified in the coprocultures. The silvopasturing horses had the highest prevalence of the helminth parasites. The percentage of horses passing ascarid eggs was significantly higher in pasturing horses younger than 3 years. The prevalence of strongyles was statistically greater in the oldest grazing equines. Mares reached the highest prevalence of helminth egg output. Our results showed that native horses kept under silvopasture had the highest prevalence of the ascarids, strongyles and oxyurids, possibly due to their exposure to contaminated grazing areas, lack of appropriate feeding and control of their health status. We conclude that silvopasture increases the presence of infection by gastrointestinal nematoda in wild horses, especially by strongyles. Suitable measures to control parasitic diseases affecting horses in silvopasture should be considered in those systems.

Intrinsic Factors Influencing the Infection by Helminth Parasites in Horses under an Oceanic Climate Area (NW Spain).

A coprological survey to determine the influence of some intrinsic factors (breed, age, and sex) on the infection by helminth parasites in equine livestock (n = 418) under an oceanic climate area (NW Spain) was conducted. Faecal samples were individually collected and analyzed by the coprological techniques. The main strongylid genera identified were Trichonema and Cyalocephalus spp (small strongyles) and Strongylus and Triodontophorus (large strongyles). The prevalence of gastrointestinal nematode was 89% (95% CI 86, 92) and 1% cestoda (0, 2). The percentage of horses with strongyloid parasites was 89% (86, 92), 11% (8, 14) for Parascaris, and 3% (1, 5) for Oxyuris. The highest prevalence for ascariosis was observed in the youngest horses (<3 years), for oxyurosis in the >10 years animals, and for strongylosis in the 3-10 years ones. Females were significantly more parasitized than males. A negative correlation between the age and the egg-excretion of ascarids and strongyles was recorded. The autochthonous and the English Pure Blood horses were the most parasitized. We concluded that the infections by helminths, especially the strongyloids, are significantly common in the region, so that greater importance should be given to this situation.