A cross-sectional coprological survey of liver flukes in cattle and sheep from an area of the southern Italian Apennines

A cross-sectional coprological survey of liver flukes (Fasciola hepatica and Dicrocoelium dendriticum) was conducted on 81 bovine farms and 197 ovine farms with animals pasturing in an area (3971 km(2)) of the southern Italian Apennines. The farms were selected to be uniformly distributed throughout the study area using geographical information system (GIS) software. Between June 1999 and March 2000, faecal samples were collected from 975 cattle and 3940 sheep and examined using a modified McMaster technique. The results were subjected to statistical analysis and point distribution maps (PDMs) were drawn by GIS.Cattle of 9 of the 81 (11.1%) farms were positive for F. hepatica and of 43 (53.1%) for D. dendriticum. Sheep of 8 of the 197 (4.1%) farms were positive for F. hepatica and of 133 (67.5%) for D. dendriticum. Co-infection was found in cattle of 2 (2.5%) farms, and in sheep of 8 (4.1%) farms.The findings of the present survey show that D. dendriticum was the predominant liver fluke found in cattle and sheep with respect to egg count numbers for both farms and animals. In addition, the general trends of the PDMs show that D. dendriticum was widely and homogeneously spread throughout the study area, whereas F. hepatica was present only in a few concentrated zones of the study area that had both positive bovine and positive ovine farms.     

Use of remote sensing and geographical information systems to identify environmental features that influence the distribution of paramphistomosis in sheep from the southern Italian Apennines

A geographic information system (GIS) was constructed using remote sensing (RS) and landscape feature data together with Calicophoron daubneyi positive survey records from 197 georeferenced ovine farms with animals pasturing in a 3971 km(2) area of the southern Italian Apennines. The objective was to study the spatial distribution of this rumen fluke, identify environmental features that influence its distribution, and develop a preliminary risk assessment model. The GIS for the study area was constructed utilizing the following environmental variables: normalized difference vegetation index (NDVI), land cover, elevation, slope, aspect, and total length of rivers. These variables were then calculated for "buffer zones" consisting of the areas included in a circle of 3 km diameter centered on 197 farms. The environmental data obtained from GIS and RS and from data taken by the veterinarians on the field (stocking rate and presence of streams, springs and brooks on pasture) were analyzed by univariate (Spearman and ANOVA) and multivariate (discriminant) statistical analyses using the farm coprological status (positive/negative) as the dependent variable. Sheep on 32 of the 197 (16.2%) farms, were positive for C. daubneyi, with an average intensity of 52 epg. A multivariate stepwise discriminant analysis model was developed that included moors and heathland, sclerophyllous and coniferous forest vegetation, autumn-winter NDVI and presence of streams, springs and brooks on pasture. The variables entered in the model were also correlated with C. daubneyi positive farms in the univariate tests and are consistent with the environmental requirements of C. daubneyi and its snail intermediate host.     

Infection of Lymnaea truncatula and Lymnaea glabra by Fasciola hepatica and Paramphistomum daubneyi in farms of central France

Natural infection of Lymnaea glabra and Lymnaea truncatula by Fasciola hepatica and/or Paramphistomum daubneyi was studied at two periods of risk (June-July and September-October) in 11 French farms known for their high prevalences of F. hepatica infection in ruminants. A total of 1,778 L. truncatula and 2,396 L. glabra measuring 6 mm or more in height were collected to determine the prevalence of natural infection with F. hepatica and P. daubneyi. The role of four factors, i.e. season, snail co-infection (F. hepatica-P. daubneyi), ruminant host and the existence of single or mixed intermediate host communities, was investigated. There were no differences in prevalences between the two risk periods. Co-infections in L. glabra were more frequent than expected. The prevalences of infection with F. hepatica or P. daubneyi in L. glabra were higher in farms rearing sheep than in farms rearing cattle. A similar finding was also noted for L. truncatula infected with P. daubneyi only. L. glabra was a much better intermediate host for F. hepatica and P. daubneyi when it was the only available snail, possibly indicating an adaptation of parasites to their less usual host in local conditions. The two trematodes preferably developed in L. truncatula rather than in L. glabra when both host species lived in the same places.     

Assessment of climatic and orographic conditions on the infection by Calicophoron daubneyi and Dicrocoelium dendriticum in grazing beef cattle (NW Spain)

From February 2003 to March 2004, 1148 faecal samples from autochthonous Rubia Gallega cattle breed were collected in 170 farms from Lugo (NW Spain), in order to find out the prevalence and intensity of egg-excretion by Calicophoron daubneyi and Dicrocoelium dendriticum, and the possible influence of external factors as annual mean temperature and rainfall, altitude and mean slope. Twenty-six percent (95% CI 19%, 33%) and the 18% (12, 24) of the farms were infected with rumen and lancet flukes. C. daubneyi egg-output (Me=24) was found in 13% (11, 15) of the individual samples. Six percent (5, 7) of the animals in the study had low D. dendriticum eggs (Me=8). By estimating the odds ratio values it was shown that the highest probability of infection by C. daubneyi was in pastures with a mean slope of less than 13% (OR=1.9) and situated under 600 m (OR=1.6). Annual mean rainfall and temperature were not identified as risk factors for the infection with rumen flukes. Mountainous pastures with a mean slope of higher than 25% (OR=5.8) and situated over 600 m (OR=24.6) where precipitation was high (>1000 mm; OR=7) and temperature low (<11 degrees C; 2.8) had involved the highest risk of infection by D. dendriticum. Because of the prevalences found in this study, employment of suitable management practices with strategic treatments with efficacious anthelmintics are needed to reduce the presence of both trematodes and to increase the health status of grazing beef cattle.     

Prevalence and significance of gastrointestinal helminths and protozoa in South American Camelids in Switzerland

A cross sectional study was conducted to determine the prevalence and significance of endoparasitic infections in South American Camelids (SAC) in Switzerland. Qualitative and quantitative coproscopic examinations were performed in 38 farms during the grazing period. Management practices with possible interference with parasitic infections were analyzed. On the farm level prevalences of endoparasitic infections were: trichostrongyles 87%; Trichuris sp. 74%; Capillaria sp. 68%; Nematodirus battus 63%; Nematodirus sp. 53%; Dicrocoelium dendriticum 34%; Moniezia sp. 8%; Fasciola hepatica 5%; protostrongylids 5%; Eimeria macusaniensis 68%. The level of helminth egg excretion was generally low. The highest values were recorded for trichostrongyles with an average of all investigated farms of 53 eggs per gram of faeces. The mean trichostrongyle egg output was approximately three-fold in SAC on farms that also kept sheep and/or goats, although this difference was not significant (P = 0.11). Clinical trichostrongylidosis was not reported from any of the farms. The low infection level with gastrointestinal nematodes is attributed to the defaecation behaviour of the SAC depositing their faeces focally on small spots on pasture. As a consequence, pasture infectivity is largely restricted to the area adjacent to the dung piles. Dicrocoeliosis is regarded as the most relevant parasitic infection of llamas and alpacas in Switzerland causing severe clinical symptoms and death in untreated animals. Sixteen per cent of the owners regularily treated their herds against dicrocoeliosis using praziquantel at a dose of 50 mg/kg body weight orally.     

The survival of nematodes and cestodes of sheep in the pasture during the winter in eastern Norway

Using 21 worm-free lambs in paddocks on old sheep pastures on 4 farms near Oslo, it was found that Nematodirus spp., Ostertagia spp. and Moniezia spp. were the only helminths which could survive the winter in the pasture in great numbers. A few Teladorsagia davtiani, Chabertia ovina, Trichuris ovis, Cooperia onchophora and Skrjabinema ovis survived the winter. Trichostrongylus axei, T. vitrinus and Oesophagostomum venulosnm showed a negligible ability to survive the winter in the pasture. The following species were never found to survive: Haemonchus contortus, Trichostrongylus colubriformis, Bunostomum trigonocephalum, Cooperia curticei and Strongyloides papillosus.     

Liver flukes promote cholelithiasis in sheep

The main objective of this study was to investigate whether cholelithiasis in sheep is related to parasitism or other commonly observed disorders such as liver abscesses. Additionally, the features of the observed biliary calculi are described. The livers of 254 randomly selected clinically healthy adult dairy sheep were used. All visible concretions in the bile were considered as stones. Based on the macroscopical examination, 60 livers were normal, 40 were parasitized with Fasciola hepatica, 42 were parasitized with Dicrocoelium dendriticum, 28 were parasitized with both D. dendriticum and F. hepatica, 40 livers had abscesses and 44 had hydatid cysts. Biliary calculi were detected in 40 livers. Twenty livers had pigment stones and 20 livers had cholesterol stones. The percentage of cholelithiasis was significantly higher in livers parasitized with flukes compared with the others (P<0.05) and the parasitoses with F. hepatica and D. dendriticum were proven to be significant risk factors (P<0.05) for the presence of cholelithiasis in sheep.     

Helminth parasitisms among intermingling insular populations of white-tailed deer, feral cattle, and feral swine.

Helminth infections among free-ranging, intermingling populations of white-tailed deer (Odocoileus virginianus), cattle (Bos taurus), and swine (Sus scrofa) on an island off the Georgia coast were studied. Of 39 species of helminths collected, 19 were found in deer, 17 in cattle, and 13 in swine. Of 28 species of helminths recovered from ruminants, 8, viz, Capillaria bovis, Cooperia punctata, Dictyocaulus viviparus, Gongylonema pulchrum, G verrucosum, Haemonchus contortus, Moniezia benedeni, and Trichostrongylus axei, occurred in both deer and cattle. Common liver flukes (Fasciola hepatica) infected cattle and swine but not deer. Only 1 helminth, G pulchrum, infected deer, cattle, and swine. The findings suggested that helminths harbored by the host species are distinct, with little exchange occurring.     

The possibilities and limitations of evasive grazing as a control measure for parasitic gastroenteritis in small ruminants in temperate climates

Between 1999 and 2003 studies were done at Utrecht University on the population dynamics of gastrointestinal nematodes and the potential to use evasive grazing for the control of nematode infections in small ruminants. On most pastures grazed in May and June it took at least 3 weeks before high pasture infectivity levels for Haemonchus contortus developed while it took at least 2 weeks on pastures grazed in July, August and September. Occasionally, larvae emerged earlier on pasture when high temperatures coincided with rain. Pasture infectivity levels for H. contortus subsequently increased and the highest levels were found between 5 and 9 weeks on pastures grazed in May-June and between 3 and 9 weeks on pastures grazed in July, August and September. Pasture infectivity usually had decreased again to low levels after approximately 3 months. Larvae of the other trichostrongylids emerged later on pasture. However, patterns of Teladorsagia circumcincta, Trichostrongylus spp. and Cooperia curticei were basically similar to H. contortus. Strongyloides papillosus larvae emerge within 2 weeks on pasture and survival is short. On the other hand Nematodirus larvae took a lot longer to emerge on pasture than the other trichostrongylids. The results imply that only on a small proportion of farms (mixed dairy cattle/sheep farms; some organic dairy goat farms) evasive grazing can be recommended as only control measure for parasitic gastroenteritis. However, the present data offer possibilities to combine evasive grazing with other methods in an integrated control scheme.     

Overview of helminth problems in domestic ruminants in Switzerland

Potent anthelmintics were introduced into the Swiss market several decades ago. Despite this, gastrointestinal nematodes (GIN), lungworms and the large liver fluke (Fasciola hepatica) can successfully inhabit Swiss ruminant farms. This is mainly due to a high reproductive capacity as well as very efficient survival strategies. In addition some species readily develop anthelmintic resistance. GIN-infections in young cattle are under comparatively good control. However, prophylactic measures are compromised where adult stock is also affected due to incomplete development of immune protection. Under these circumstances control measures must include all age groups. This results in fewer helminths in refugia thus may accelerate the development of anthelmintic resistance. This review aims to present a synopsis of the significance of the major helminth infections obtained on pasture by large and small ruminants in Switzerland. Currently available strategies for strategic helminth control are summarized and an outlook is given on new developments which might expand the spectrum of control measures relevant for veterinary practice in the future.     

The influence of different food sources on cercarial production in Lymnaea truncatula experimentally infected with Digenea

Experimental infections of Lymnaea truncatula with a digenean species (Fasciola gigantica, F. hepatica, or Paramphistomum daubneyi) were performed under laboratory conditions to study the effect of four sources of food (microalgae, romaine lettuce, wheat germs, or modified Boray diet) on cercarial production. The mean number of F. hepatica, F. gigantica, or P. daubneyi cercariae was significantly greater when snail food was microalgae or Boray diet. The lowest cost prices for 100 metacercariae of F. hepatica (9.7-10.1 euros) were noted when algae of Boray diet were used as food for snails. In contrast, the highest prices (18.0-18.5 euros) were found in lettuce-reared snails. The choice of a source of food for breeding the intermediate hosts of F. hepatica and collecting metacercariae must take into account the importance of the commercial demand for metacercariae and will depend on the strategy the producer wishes to develop.     

The epidemiology of abomasal nematodes of sheep in Sweden, with particular reference to over-winter survival strategies

In May 2002, studies on the seasonal patterns of nematode infection of sheep were undertaken on four commercial sheep farms in southern Sweden, which had previously reported problems with nematode parasitism, especially due to Haemonchus contortus. One farm was used for intensive investigation. This entailed the establishment of two replicate groups of sheep, each consisting of 20 ewes and their lambs, on adjacent pasture paddocks. The seasonal patterns of nematode infection were followed by regular (approximately monthly) sampling of both ewes and lambs for nematode faecal egg counts and larval differentiation, and the sequential use of replicate groups of tracer lambs. H. contortus and Teladorsagia circumcincta were the most abundant nematode species, with the former most prevalent in the post-parturient faecal egg counts of ewes. Tracer worm counts showed almost 100% arrested development in the early fourth larval stage for H. contortus as early as mid-summer and the numbers of parasites progressively increased during the season. T. circumcincta also showed high levels of arrested development, but not as early, or as absolute, as for H. contortus. Tracers allocated to the paddocks at the time of turn-out following winter in May 2003, showed virtually a total absence of H. contortus in contrast to exceedingly high infections with T. circumcincta. Results of the three additional monitoring flocks supported these findings. It can be concluded that under Swedish sheep farming conditions, H. contortus has evolved to survive the long, cold winters entirely within the host as the arrested larval stage, relying on the lambing ewe to complete its life cycle. The peri-parturient relaxation of resistance in the ewes triggers the resumption of development to the adult egg-laying parasites to result in pasture contamination and the completion of just one parasite generation/year. In contrast, T. circumcincta can survive well over-winter, both on pasture and within the host.     

Cross-sectional study of risk factors for the clinical expression of ovine Johne's disease on New South Wales farms

OBJECTIVE: To explore the environmental and management risk factors that promote the clinical expression of ovine Johne's disease on farms in New South Wales. DESIGN: Cross-sectional study. PROCEDURE: A questionnaire about the farm, flock and their management was mailed to all farmers known to keep infected sheep in the area zoned residual for ovine Johne's disease in New South Wales. The resultant data were analysed by multivariate statistical methods, specifically examining the factors associated with farmers reporting some mortality due to ovine Johne's disease; the reported annual incidence of ovine Johne's disease-associated mortality; the youngest age at which sheep die from ovine Johne's disease; whether scouring was a feature of the disease; and the season of peak mortality from ovine Johne's disease. RESULTS: Fine wool Merino sheep were more likely to die from ovine Johne's disease than other sheep types. Mortality was higher on farms with light sandy soils and those with a high proportion of improved pastures containing subterranean clover. Winter shearing was also associated with clinical expression. The time that the infection had been present on a farm was not strongly associated with mortality. Higher stocking density, high rainfall and access to open water, factors that are believed to aid transmission, were not found to be influential. CONCLUSION: Clinical expression appears to be principally associated with light infertile soils and their associated pastures and pasture improvement practices which may lead to micronutrient deficiencies or imbalances. Genetic effects are also important and are likely to be exacerbated by physiological stressors, such as winter shearing.     

Studies on the pathology of dicrocoeliasis and fascioliasis in the goat. 3. The histochemistry of mast cells and globule leucocytes

Comparative studies were made on the structure and histochemistry of mast cells and globule leucocytes in dicrocoeliasis and fascioliasis of the goat. Investigations showed that D. dendriticum and F. hepatica infections in the goat produce an increase in the number of hepatic mast cells and frequent occurrence of globule leucocytes in the epithelium of the bile ducts. The only difference between these infections was that globule leucocytes were more frequent in small bile ducts in dicrocoeliasis than in fascioliasis.Histochemical methods showed the presence of sulphomucins in the granules of mast cells, while both neutral mucins and carboxymucins were revealed in the globules of globule leucocytes. The acidity of the mucosubstances could not be shown to result from hyaluronic acid, chondroitin-4 and -6-sulphates, or sialic acid. The globules of globule leucocytes also contained histochemically identifiable highly basic proteins.Keyword: Dicrocoelium dendriticum, Fasciola hepatica, liver, bile ducts, mast cell, globule leucocyte     

Prevalence of Paramphistomum daubneyi infection in cattle in central France

Investigations at the slaughterhouse of Limoges (Central France) were performed in 1994-1996 to determine the prevalence of Paramphistomum daubneyi infection in cattle. In 1994/1995, higher prevalences of P. daubneyi were recorded in May, October, and January. In 1996, smaller variations were recorded, and prevalence in April and May was higher. The prevalence of P. daubneyi in summer was lower. Breed and age of cattle were not significantly associated to P. daubneyi infection, but females were significantly more infected than males. P daubneyi infection was related to that of Fasciola hepatica, but not to that of Dicrocoelium lanceolatum.     

Husbandry management, worm control practices and gastro-intestinal parasite infections of sows in pig-breeding farms in Münsterland, Germany

A cross-sectional survey was performed on 144 farms randomly selected from 3 breeding organisations in Münsterland, Germany, to obtain representative data on husbandry management, worm control practices and their possible associations with gastro-intestinal parasite infections in sows. Straw bedding was provided in the majority of gestation units; lactating sows were frequently kept strawless. Pasturing of gilts and non-lactating sows were performed in 37% of the farms. Sows were treated with anthelmintics (mainly benzimidazoles, ivermectin or levamisole) in 98% of the farms. The proportions of farmers performing the 'targeted' (mainly prefarrowing) or 'non-targeted' treatment strategy (treatment of all animals several times per year) were similar. Piglets were anthelmintically dosed in only 19% of the farms. Patent infections of sows with Oesophagostomum spp., Ascaris suum, Trichuris suis and Eimeria spp. were detected in 79%, 7%, 8% and 29% of all the farms, respectively. Hyostrongylus rubidus infections were only found in farms with pasturing. The within-farm prevalences of both the strongylid and Eimeria infections were negatively correlated with the herd size but positively with the weaning age. Risk factors for strongylid infections were straw bedding in pens and pasturing. Pasturing was a risk factor for Eimeria infections too. There was a positive association between the time interval to last deworming of sows and strongylid egg counts. However, neither the treatment strategy nor the anthelmintic class used was associated with nematode infections. No relations were found between different cleaning methods in stables and endoparasite infections.     

Relationship between helminth species diversity, intensity of infection and breeding management in dairy goats

Helminth infection, species diversity (proportion of each species in the community), species number, intensity of infection and anthelmintic resistance were investigated in 16 dairy-goat farms of south-western France. The aim of the study was to estimate which breeding management factors may affect diversity and intensity of infection. Anthelmintic resistance was investigated because this factor may modify composition of nematode communities. Farm history and breeding management were recorded by means of a questionnaire. Natural and experimental infections were compared to determine which strategy was the best to estimate diversity index and number of species from nematode community of a whole herd. A total of 17 species of helminths, among which 14 nematodes, one cestode (Moniezia spp.) and two trematodes (Paramphistomum daubneyi and Dicrocoelium lanceolatum) were recovered in the 26 necropsied culled goats. One culled goat worm burden represented conveniently species number but not species diversity (Shannon index) of parasite community harboured in the whole herd. Experimental sheep infection with larvae from pooled faeces of 15 goats was the best strategy to estimate species diversity in farms. Diversity could be predicted from the number of farms from which goats originated at constitution of the herd, the duration of goat winter withdrawal from pastures, and intensity of infection. Anthelmintic resistance was correlated with the number of farms of origin, area of permanent pastures and intensity of infection. The strategy adopted for the herd constitution was a critical step as species diversity and risk of anthelmintic resistance increased with the number of farms of origin. Intensity of infection was negatively correlated with species diversity. This suggested that more diverse communities were better controlled by the host, in agreement with the widespread statement that diversity would beget stability.     

Spatial Relative Risk Mapping of Pseudorabies‐Seropositive Pig Herds in an Animal‐Dense Region

This paper describes a new approach for spatial relative risk mapping as a tool for geographical risk assessment. The spatial epidemiological analysis is based on geographically referenced data about pseudorabies (Aujeszky's disease) virus infections at farm level in a region of high animal density in Germany at the beginning of the national eradication project. On the basis of serological findings 186 farms were classified as positive out of a total of 482 investigated farms listed in veterinary administrative registers. Geographical cluster analysis was used to identify two areas of high risk (RR = 2.4 and 3.3). Non‐parametric density estimation was used to estimate the proportion of infected farms per square kilometre. Furthermore, the spatial relative risk function was approximated through the prevalence ratio defined by the ratio of the local prevalence and the overall prevalence of the farms outside the cluster regions. The corresponding approximated relative risk map indicates and quantifies a clear spatial pattern of disease frequency.     

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

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