Contribution to the Knowledge of Gastrointestinal Nematodes in Roe Deer (Capreolus capreolus) from the Province of León, Spain: An Epidemiological and Molecular Study

A study of gastrointestinal nematodes in roe deer was carried out in the regional hunting reserves of Riaño and Mampodre, Province of León, Spain, to provide information on their prevalence and intensity of infection in relation to the sampling areas, age of the animals, and body weight. Through a regulated necropsy of the animals, all of them harbored gastrointestinal nematodes in their digestive tract, with a mean intensity of parasitism of 638 ± 646.1 nematodes/infected animal. Eleven genera were found and 18 species of gastrointestinal nematodes were identified, three of them polymorphic: Trichostrongylus axei, Trichostrongylus vitrinus, Trichostrongylus capricola, Trichostrongylus colubriformis, Haemonchus contortus, Spiculopteragia spiculoptera/Spiculopteragia mathevossiani, Ostertagia leptospicularis/Ostertagia kolchida, Ostertagia (Grosspiculopteragia) occidentalis, Teladorsagia circumcincta/Teladorsagia trifurcate, Marshallagia marshalli, Nematodirus europaeus, Cooperia oncophora, Capillaria bovis, Oesophagostomum venulosum, and Trichuris ovis. All of them have already been cited in roe deer in Europe, but Marshallagia marshalli, Capillaria bovis, and Ostertagia (Grosspiculopteragia) occidentalis are reported for the first time in Spain in this host. The abomasum was the intestinal section, where the prevalence (98.9%) and mean intensity (x¯ = 370.7 ± 374.4 worms/roe deer; range 3-1762) were significantly higher, but no statistically significant differences were found when comparing the sampling areas and age of animals. The animals with lower body weight had a higher parasite load than those in better physical condition, finding, in this case, statistically significant differences (p = 0.0020). Seven genera and 14 species were identified. In the small intestine, 88% of the animals examined presented gastrointestinal nematodes, with an average intensity of x¯ = 131.7 ± 225.6 parasites/infected animal, ranging between 4-1254 worms. No statistically significant differences were found when the three parameters studied were compared. Four genera and seven species were identified. In the large intestine/cecum, 78.3% of the examined roe deer presented adult worms, with an average intensity of 6.3 ± 5.5 worms/infected animal; range 1-26 worms. Only statistically significant differences were observed when considering the mean intensity of parasitism and the sampling area (p = 0.0093). Two genera and two species were identified. Several of the species found in the study were studied molecularly, and with the sequences obtained compared with those deposited in GenBank, phylogenetic trees were prepared to determine their taxonomic status. Using coprological techniques, the existing correlation in the shedding of gastrointestinal nematode eggs in roe deer was investigated with that of semi-extensive sheep farms in the same study area to verify the existence of cross-transmission of these parasites between wild and domestic animals. The high values found in the studied parameters show that northern Spain is an area of high-intensity infection for roe deer.

Antigen characterization from second instars of oestrid bot flies for the detection of anti-Cephenemyia stimulator antibodies by ELISA in roe deer (Capreolus capreolus)

A study to determine the most appropriate antigen for use in the serodiagnosis of Cephenemyia (Diptera: Oestridae) infestation in roe deer (Capreolus capreolus) was carried out using immunoenzymatic tests. Serum samples from 43 roe deer from northern Spain were obtained post-mortem and corresponding numbers of bot fly larvae established. Three antigen complexes were tested, including Cephenemyia stimulator Clark excretory/secretory antigens (CsES), C. stimulator somatic antigens (CsSA) and Oestrus ovis L. (Diptera: Oestridae) excretory/secretory antigens (OoES). In addition, the composition of each antigen was analysed using an electrophoresis system. Cephenemyia stimulator larvae were found in 25% of roe deer; the mean intensity of infection was 24.3 larvae per infested animal. In the antigen analysis, CsSA showed four exclusive bands of molecular weight (17-19, 62, 65 and 67-70 kDa). A positive correlation between immunoglobulin G (IgG) values and total number of larvae was found with CsES and CsSA. The highest sensitivity value, negative predictive value and negative likelihood ratio were obtained using CsES. The highest specificity value, positive likelihood ratio and kappa value were achieved with CsSA. The predictive values of the enzyme-linked immunosorbent assay (ELISA) using CsES and CsSA reached statistical significance and seroprevalence values were 26-44%. The use of ELISA with CsES and CsSA seems promising in the non-invasive diagnosis of Cephenemyia infestation in roe deer.

Gastrointestinal nematode infections in roe deer (Capreolus capreolus) from the NW of the Iberian Peninsula: assessment of some risk factors

Intestinal contents of 218 roe deer hunted in the northwest (NW) of the Iberian Peninsula during the 2008-2009 hunting seasons were examined in order to provide information on the gastrointestinal (GI) nematode prevalence and intensity of infection and the possible influence of some environmental and intrinsic factors such as climatic conditions, age and sex. All the animals studied harboured GI nematodes, and a total of 20 different species belonging to ten genera were identified. Spiculopteragia spiculoptera/Spiculopteragia mathevossiani, Ostertagia leptospicularis/Ostertagia kolchida and Nematodirus filicollis were the most common. This is the first citation for Chabertia ovina, Cooperia pectinata, Cooperia punctata, Cooperia oncophora, Haemonchus contortus, Nematodirus spathiger, Oesophagostomum venulosum, Teladorsagia trifurcata, Trichostrongylus capricola, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Trichuris capreoli in roe deer from the Iberian Peninsula. Prevalence and intensity were significantly higher in the abomasum, where infections with more than one GI nematode species were the most common; in the other intestinal segments infections with only one GI nematode species were the most prevalent. When considering the influence of the different risk factors on the prevalence of GI nematodes, the highest prevalence for most of the genera were observed in roe deer from coastal areas, where climatic conditions are more favourable for the development and survival of third stage larvae in the environment. Regarding the sex of the animals, the prevalence was, in general, higher in males than in females, probably due to behavioural and physiological sex-related differences. On the contrary, no differences were found in relation to the age of the animals. This study reveals that roe deer from the NW of the Iberian Peninsula are widely and intensely infected with gastrointestinal nematodes, which probably affect the health status of these ungulates.

Toxocara canis larvae viability after disinfectant-exposition

The effect of three routinely used disinfectants on the embryonary development of Toxocara canis eggs was evaluated both in vivo and in vitro. In the in vitro experiment, T. canis eggs were treated with the ethanol, sodium hypochlorite, and one commercial mix of benzalconium chloride and formaldehyde, and the embryonary development was assessed. After a period of 24 days incubation, ethanol was the best disinfectant because it prevented the development of the T. canis larvae 2 in the eggs, and sodium hypochlorite caused degeneration in 50% eggs. By using the commercial mix, 25% T. canis eggs developed to 2nd stage larvae. In the in vivo experiment, the embryonated eggs treated with the disinfectants were inoculated to mice, and their brain tissues were examined for larval presence on the 24th day postinfection. In addition, a control group was set up for comparison with the infected groups. No injury or T. canis larvae were observed in mice infected with sodium hypochlorite-treated eggs, opposite to that recorded in the animals infected with the commercial disinfectant-treated eggs. These results showed that both ethanol and sodium hypochlorite are very appropriate because of their full efficacy against infective T. canis eggs. Disinfection of kennels, animal shelters, cages, and veterinary clinics with one of these products to eliminate T. canis eggs and to avoid contamination is strongly recommended.

Larval development of Neostrongylus linearis (Nematoda, Protostrongylidae) in the mollusc Cochlicella barbara infected and maintained in a subhumid area (north-west Spain) and its possible influence on the infection of small ruminants

Twelve batches of 100 Cochlicella barbara (Mollusca, Helicidae) were deposited monthly, from January to December in plots (0.5 x 0.5 m) with faeces of sheep containing first-stage larvae of Neostrongylus linearis in order to be naturally infected, and another 12 batches acted as uninfected controls. Every 2 weeks dead molluscs were removed from the plots and three to five specimens were examined to study larval development in the snail. Infected and control snails did not differ in their mortality, which may be associated with the low rate of infection of snails. The highest number of molluscs that were infected and the maximum level of infection were observed in batches deposited in summer months. There was a positive correlation between the percentage of infected snails and temperature. Molluscs harboured higher number of infectious third-stage larvae (L3) from mid-spring to mid-autumn and especially in summer months; thus under these climatic conditions and periods small ruminants are more likely to get infected by N. linearis.

Efficacy of moxidectin 1% injectable and 0.2% oral drench against natural infection by Dictyocaulus filaria in sheep

Two separate trials (I and II) with 34 and 32 Churra ewes, respectively, and distributed into two groups, have been carried out to evaluate the efficacy of two different formulations of moxidectin at a dose rate of 0.2mg/kg body weight (b.w.) against natural infection by Dictyocaulus filaria in sheep. Trial I was designed to evaluate a 1% moxidectin injectable formulation, whereas in trial II a 0.2% moxidectin oral drench formulation was used. The efficacy was measured on the basis of the reduction of the faecal larval counts and of adult worm recoveries at slaughter. In each trial, a group of animals was treated on day 0 with moxidectin 1% injectable or moxidectin 0.2% oral drench and the other group acted as untreated control. When the faecal larval counts was compared within the treated groups, the efficacy was over 95% until day +13, and 100% at the remainder of the sampling dates after the application of injectable moxidectin, whereas in trial II, the larvae per gram (lpg) of faeces increased until the first sampling time post treatment (p.t.), day +6, and zero counts were recorded for all animals by the following days. On the basis of adult worm recoveries at necropsy, the efficacy of the treatment was 100% in both trials, however, adult worms were detected at slaughter for all control sheep. These results indicate that moxidectin 1% injectable and moxidectin 0.2% oral drench, administered at 0.2mg/kg b.w., were 100% effective against D. filaria infection in sheep. No adverse reactions to the treatments were observed in the animals.

Efficacy of moxidectin 1% injectable against natural infection of Sarcoptes scabiei in sheep

Thirty ewes naturally infected with Sarcoptes scabiei var. ovis, were allocated into three groups of 10 animals each. Animals in groups B and C were treated on day 0 and on days 0 and +10, respectively, with moxidectin 1% injectable at a dose of 0.2mg moxidectin/kg body weight (BW). Group A remained untreated. Seven days before treatment, the geometric mean of Sarcoptes scabiei var. ovis per square centimeter of skin in groups A, B and C were not significantly different. From the day of treatment to the end of the trial, the average number of mites/cm(2) increased in untreated animals and decreased in groups B and C, but these values were higher for group C. Active lesions produced by S. scabiei var. ovis consistently increased during the trial in the untreated animals; in group B the minimum count occurred on day +56 this reduction being more evident in group C (no lesions on days +49 and +56). Also in this group, the number of cured animals was 100%, therefore, the application of two treatments with moxidectin (group C) showed higher efficacy than a single treatment (group B). Body condition score decreased in the three experimental groups along the trial. All animals were individually weighed on days -1, +28 and at the end of the trial. No adverse reactions were observed in the animals treated with 0.2mg moxidectin/kg BW.

Bronchopulmonary helminths of roe deer (Capreolus capreolus) in the northwest of Spain

From 1993 to 1995, 148 hunter killed roe deer (Capreolus capreolus L.) from game reserves in Lugo (northwestern Spain) were examined for lungworm infection. The overall prevalence of infection was high (66.2%). Infections were comprised to two species, Varestrongylus capreoli and Dictyocaulus noerneri with a prevalence of 62.0 and 18.2%, respectively. Significant differences in the prevalence and larval burdens in lungs and faecal samples were observed between different locations. The highest overall prevalence of lungworm infection was observed in the large reserve at Ancares (78%) in comparison to that in smaller reserves (61.7%). Considering that the species recorded in this study are highly host-specific, it is unlikely that roe deer represent a significant reservoir of lungworm transmissible to domestic ruminants in northwestern Spain.

Dynamics of the antibody response in cattle infested by Hypoderma (Diptera: Oestridae) after a treatment with injectable and pour-on ivermectin

The dynamics of the anti-Hypoderma antibody response after a treatment with injectable and pour-on ivermectin against first instars of Hypoderma sp. were determined in naturally infested cows. Cattle were randomly assigned to three groups: group 1, which served as an untreated control; group 2, treated with pour-on ivermectin at a dose of 500 microg/kg of body weight, and group 3, which received 200 microg/kg of body weight of ivermectin by subcutaneous injection. Both ivermectins showed total efficacy against L-1 of Hypoderma sp. In untreated control animals, grubs became detectable in the 2 mo after treatment. Indirect enzyme-linked immunosorbent assay (ELISA) showed a significant increase in group 3 antibody levels 1 mo after treatment, whereas in group 2 the increase was not significant. Following the peak of anitibody activity in group 3, antibody levels declined at a faster rate than in those treated topically. In both treated groups, cattle remained serologically positive for 4 mo after ivermectin treatment. Thus, serological surveillance programs for cattle grubs conducted during this posttreatment period will not be influenced by treatment with ivermectin. The persistence of antibody levels after larval destruction makes the indirect ELISA unsuitable for the prediction of the efficacy of treatment.

Faecal egg output, contamination of pastures and serum pepsinogen concentrations in heifers with natural gastrointestinal nematode infections in north-west Spain

In 1988, 1989 and 1990 second year grazing heifers, naturally infected with gastrointestinal nematodes, were separated into two groups, one of which was treated orally with albendazole. In 1988 and 1989 treatment was administered immediately after parturition (February), and in 1990 during the last term of pregnancy (December). Both treated and control animals were grazed on separate plots in a rotational system. Maximum faecal egg counts were observed around parturition, except in 1990, when treatment was given at the end of gestation. The main genera identified were Cooperia, Trichostrongylus, Ostertagia and Oesophagostomum. The number of Ostertagia larvae in the treated groups increased from 1989 to 1990, while the others decreased. Pasture contamination with third stage larvae (L3) was lower on the plots grazed by treated heifers. Maximum numbers of L3 were found in autumn, at the end of winter, and at the beginning of spring. Mean serum pepsinogen concentrations were significantly higher in the untreated groups. This concurs with the pattern for L3 on pasture. The trial shows that if a single treatment against gastrointestinal nematodes is carried out, and the animals remain on contaminated pastures, the parasitic load tends to level out after 4-5 months under favourable climatic conditions. However, the percentages of nematode genera occurring in the new populations may differ from those in the original infection.