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The prevalence and aetiology of natural paramphistomosis was investigated in cattle slaughtered in the Castilla y León region (Spain) over a 3 year-period. The overall prevalence of positive animals was 6.20%. The parasite burden per animal ranged from 8 to 8005 (median=144) and the ruminal atrium had the highest parasite burden whereas the ruminal dorsal sac the lowest. The prevalence and parasite burden increased with age while these parameters were lower in cattle under intensive management. Calicophoron daubneyi was the only Paramphistomidae species identified using morphoanatomical, histological and molecular methods in the studied animals., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: In the present study we studied and updated the prevalence of the infections caused by gastrointestinal nematodes (GIN) and Fasciola hepatica in grazing sheep in the northwest (NW) of Spain for the last six years (2006-2011), and its relationship with the current climatic conditions., Methods: We analyzed faecal samples from 110 flocks located in four different provinces of the Autonomous Community of Castilla y León: 76.4% of them were situated in León, 12.7% in Zamora, 9.1% in Palencia and 1.8% in Valladolid., Results: The prevalence of GIN was 100% and the mean of eggs per gram (epg) in faeces was 237.2 (± 375.9) per flock. Regarding climatic conditions, we found a direct relationship between the GIN infection level and the maximum humidity (p<0.05) but inverse with the degree of solar radiation (p<0.05). The prevalence of fasciolosis was 59.3%, with a mean epg of 17.5 (± 33.9) per flock; these values were correlated with the minimum humidity and precipitations (p<0.05). Comparing our results in León with previous studies during the early 1990s, the mean epg of GIN was increased slightly (134.3 epg); regarding fasciolosis, the prevalence rose significantly, from 26.7% to 60.5%. Since the 1990s we observed that the maximum temperature is nowadays 0.45°C higher (17.0°C) and the minimum 0.5°C lower (5.2°C); the rainfall values were very similar in both decades but at the present time the humidity is higher (75.9%)., Conclusions: We found that the prevalence of GIN and F. hepatica infections was directly influenced by the humidity and also by precipitations in the case of F. hepatica. Comparing the current prevalence with studies carried out in the same area for the early 1990s, we observed that nowadays the mean epg of GIN is higher with a possible cause being the differences in climatic conditions depending on the sampling year. Regarding F. hepatica infection, its prevalence rose significantly probably favoured by an increase in irrigated areas in the area of study.

The transmission, control and the relationship between Dicrocoelium dendriticum and its definitive (sheep and cattle) and intermediate (molluscs and ants) hosts under natural and experimental conditions are described. Eleven species of molluscs and four of ants were found infected with larval D. dendriticum in León province, north-west Spain. Infected ants were observed between April and November and in tetania at 7.5-26.9 degrees C. The highest shedding of eggs by sheep and cattle was detected in winter. Two treatments applied in November and January were the most effective. In experimentally infected molluscs, the parasite was not visible under the stereomicroscope, at least until 50 days post-infection (p.i.). The prepatent period in experimentally infected lambs was 49-79 days p.i. The number of eggs per gram increased with the days p.i. and the parasite burden. The aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, leukocyte and neutrophil values of infected lambs increased, but those of lymphocytes decreased. Using the enzyme-linked immunosorbert assay technique, the IgG antibody response to excretory-secretory and somatic antigens of D. dendriticum was positive from day 30 p.i., although the maximum antibody levels were observed on day 60 p.i. The number of worms per lamb ranged between 30 and 2063. Cholangitis and cholangiectasia of the septal bile and hepatic ducts were observed. The best enzymatic systems for adult and larval D. dendriticum characterization were lactate dehydrogenase, glucose phosphate isomerase and phosphoglucomutase. Genetic variability of adult D. dendriticum was high using the random amplified polymorphic DNA technique.

An epidemiological study on dicrocoeliosis caused by Dicrocoelium dendriticum was carried out on sheep, molluscs and ants in the mountains of León province (NW Spain) between 1987-1991. The results concerning the intermediate hosts and a review of some aspects of dicrocoeliosis are summarized. Mollusc collection for the helminthological study was random throughout the study area at fortnightly intervals. Twenty-nine Gastropoda species were identified. D. dendriticum infection was only detected in 2.98%, of the 2084 Helicella itala examined and in 1.06% of 852 H. corderoi. The highest infection prevalence was detected in H. itala in September and in H. corderoi in February. Daughter sporocysts with well-developed cercariae predominated in spring and autumn. Infection prevalence increased with mollusc age and size. Ants were collected from anthills or plants to which they were attached. The behaviour of ants in tetania was followed. Twenty-one Formicidae species were identified, but only the following harboured D. dendriticum: Formica cunicularia (1158 examined specimens, 0.69% infection prevalence, 2-56 metacercariae per ant); F. sanguinea (234, 1.28%, 2-63); F. nigricans (1770, 4.97%, 1-186); F. rufibarbis (288, 6.59%, 2-107). In a flat area close to León town, 95.39% of the 2085 F. rufibarbis specimens collected in tetania contained metacercariae (1-240) in the abdomen. These were used for parasite characterization by isoelectric focusing and to infect lambs and hamsters. Only one brainworm per ant was found.

Water soluble extracts of 3131 adult specimens of Dicrocoelium dendriticum from cattle, sheep and goats, mainly from León province, were analysed by isoelectric focusing in thin-layer polyacrylamide gels. Activity of the following enzymes was studied: lactate dehydrogenase (LDH, EC 1.1.1.27), glucose phosphate isomerase (GPI, EC 5.3.1.9), phosphoglucomutase (PGM, EC 2.7.5.1), acid phosphatase (AcP, EC 3.1.3.2), alpha-glycerophosphate dehydrogenase (alpha-GPDH, EC 1.1.1.8), hydroxybutyrate dehydrogenase (HBDH, EC 1.1.1.30) and malate dehydrogenase (MDH, 1.1.1.37). Five distinct enzyme types were recognized for LDH (pH range 6.30-7.13), GPI (pH 6.13-6.80) and PGM (pH 6.20-6.60) whereas AcP showed three different patterns (pH 5.70-5.92). Weak and diffuse activity was detected for MDH (pH 4.8-6.2) and no activity was observed for alpha-GPDH and HBDH. In general, little phenotypic variation was observed between worms recovered from a single host, between those from hosts of the same species and between those from hosts of different species, although some enzyme types were found in some animals but not others. Nevertheless, it must be taken into account that most parasites came from sheep and also from a relatively small area in north-west Spain.

To study the distribution of Lymnaea truncatula in the Porma river basin (León, NW Spain) and its helminth fauna, malacological samplings were carried out at 66 points in the basin and the presence of these molluscs was detected in 31. To trace the dynamics of this mollusc population and the prevalence and intensity of its infection by trematodes, malacological samplings were made at fortnightly intervals over two years at five locations, situated in the upper and middle regions of the river Porma basin. To confirm the identity of the larval stages found in the molluscs, second intermediate and/or definitive hosts, depending on the trematode species, were experimentally infected to complete the life cycles. Two different species of Plagiorchiidae and one of Notocotylidae were identified. The infection prevalence of Plagiorchis elegans for the 6291 specimens of L. truncatula examined was 2.8% and infection was observed in snails collected in 7 of the 31 sample localities. This parasite was found in all months of the year, with the highest prevalence observed in July and October. When the corrected frequency values were considered, a slightly positive relationship was observed between the infection prevalence and the latter months. The highest percentages of snails harbouring immature sporocysts were detected in March and June-July, while the highest percentages with sporocysts containing mature cercariae were observed in spring and at the end of summer-autumn, and cercarial shedding in the latter. Of the 6291 L. truncatula examined 0.3% were infected by sporocysts of Opisthioglyphe ranae.(ABSTRACT TRUNCATED AT 250 WORDS)

Dicrocoelium dendriticum egg output in cattle from five locations of the Porma river basin (León Province, Northwest Spain) was studied at monthly intervals between March 1986 and March 1987. We found D. dendriticum eggs in 37.64% of the 1251 samples examined, and the number of eggs per gram (epg) ranged from 10 to 1000 (average, 41.65 +/- 2.73). The main egg-elimination period, for prevalence, was autumn-winter. The average epg values were quite similar during all months except March, when the maximum was detected. The infection prevalence increased in cattle aged up to 2 years and then a slight, gradual decrease was observed with increasing host age. The average epg values ranged from 40.08 +/- 3.24 to 48.33 +/- 12.42 in all age groups except the oldest animals, for which the figures were lower. The rate of egg elimination was higher in animals that came from locations situated at a greater altitude.

In the present study, Diplectanum laubieri was redescribed from material obtained from wild and cultured fish. The population dynamics of D. aequans and D. laubieri under culture conditions was studied. The prevalence and mean intensity (average number of worms per parasitized fish) were 80.64% and 112 for D. aequans and 67.74% and 59.61 for D. laubieri, respectively. Both Diplectanidae exhibited seasonal variations, with maximal infection levels occurring in winter, suggesting continuous parasites recruitment, and infection levels tended to increase with host age. Male hosts were more heavily infested than females. The apparent positive association between D. aequans and D. laubieri was not confirmed statistically. The Diplectanidae showed definite and different patterns of gill distribution. Histopathological gill damage mainly consisted of hyperplasia of the epithelium, fusion of branchial lamellae and the presence of hemorrhagic and inflammatory foci with leucocytic infiltration. The results demonstrated the pathological importance of both Diplectanidae for the cultivation of sea bass.