Helminths of sheep and goats in desert areas of south-west Mauritania (Trarza)

Rumen and Liver Fluke Infections in Sheep and Goats in Northern and Southern Germany

Simple Summary

Little is known about the distribution of rumen and liver flukes in sheep and goats in Germany or about the occurring rumen fluke species. These fluke infections can be detected by the parasite’s eggs in the host animal’s feces. Therefore, fecal samples from 223 sheep farms and 143 goat farms from northern and southern Germany were examined. The eggs of rumen flukes were detected on 2.2% of the samples, the eggs of common liver flukes on 2.7%, and the eggs of small liver flukes on 21.1% of the examined sheep farms. The rumen flukes were identified as the emerging species Calicophoron daubneyi. No rumen fluke eggs were detected on any of the goat farm samples, but common and small liver fluke eggs were detected in 5.6% and 7.0% of the goat herds, respectively. Differences in the geographical distribution of rumen and liver flukes between and within the two regions were identified. Rumen flukes were more frequently found in the north, while the two liver fluke species were more frequently found in the south of Germany. Sheep sharing the pasture with other ruminants were more likely to be infected with rumen flukes.

Abstract

Paramphistomidosis has recently been identified as an emerging parasitosis in Europe. This study estimated the prevalence of rumen flukes, Fasciola hepatica and Dicrocoelium dendriticum, in small ruminants in Germany and identified occurring rumen fluke species and potential predictors for fluke infections. Pooled fecal samples from 223 sheep farms and 143 goat farms in northern and southern Germany were examined by the sedimentation technique, and molecular species identification was performed on rumen-fluke-positive samples. In sheep, a flock prevalence of 2.2% was detected for rumen flukes. Calicophoron daubneyi was identified on four of five positive farms, while species identification failed in one flock. No rumen fluke eggs were detected in the examined goat herds. F. hepatica eggs were detected in 2.7% of the sheep flocks, while the herd prevalence was 5.6% in goats. Higher prevalence values of 21.1% (sheep) and 7.0% (goats) were observed for D. dendriticum. Mixed grazing with other ruminants and previously identified infections with rumen flukes and/or F. hepatica were identified as predictors for paramphistomidosis. The distribution of the three trematode species followed a geographical pattern associated with conditions favoring the relevant intermediate hosts. C. daubneyi is an established parasite in German sheep at a currently low prevalence.

Comparison of nematode infections of the gastrointestinal tract in Angora and dairy goats in a rangeland environment: relations with the feeding behaviour

A study was conducted in order to examine the possible influence of feeding behaviour on differences in the diversity and the intensity of nematode infections of the gastrointestinal tract between two breeds of goats placed in the same rangeland environment. Within the same flock bred on rangeland conditions, 10 Saanen dairy goats and 14 Angora goats were surveyed for 5 months (from May to September) and parasitological and behavioural parameters were measured. The level of nematode infection was estimated by monthly measurements of faecal egg counts whereas the feeding behaviour was assessed every fortnight. During the whole survey, nematode egg excretion was repeatedly higher in the Angora goats compared to the Saanen ones and significant differences were observed in May and September. This difference in egg excretion was related to major difference in feeding behaviour between the two breeds. In contrast with the Saanen does, Angora goats did not show any browsing and resting activities at any date of observation. Hence, Angora goats can be considered mainly as grazers whereas Saanen goats exhibit feeding activities close to browsers. The relative influence of feeding behaviour and host immune response on the susceptibility to gastrointestinal nematode infection in goats is discussed.

Ten years of research activities on tropical parasitology of dromedaries, cattle, and small ruminants in Mauritania

In the past, the essential part of the activity of the parasitology laboratory of the Centre National d'Elevage et de Recherches Vétérinaires (CNERV) was represented by diagnostic work that enabled the construction of an inventory of local parasitic fauna and a good collection of specimens. However, the small and irregular number of samples each year, led us to switch our activities in 1990 toward work that could better justify the existence of CNERV. We started work on applied research topics, such as tick-borne diseases, helminthology (nemathelminths and plathelminths), and trypanosomosis. These results were valorized through scientific publication and communication at international meetings. The most valuable information was conveyed to herders.

Ecological, morphological and genetic characterization of sympatric Haemonchus spp. parasites of domestic ruminants in Mauritania

The 4 species of ruminants (dromedary, zebu cattle, sheep and goat) in arid areas of Mauritania harboured Haemonchus spp. as the most frequent internal parasite. This was a rare situation where the 3 putative species, H. longistipes (dromedary), H. placei (zebu cattle) and H. contortus (sheep and goat) occurred sympatrically. The study was undertaken on hosts slaughtered at the Nouakchott abattoir, on the basis of monthly collection of worms. The environment was very unfavourable to H. placei and unfavourable to H. contortus, as intensity of infection remained low throughout the year, whereas infection in the dromedary was 10 to 20-fold higher. The survival strategies during the long, dry season were different: the surviving stages were either 4th-stage larvae in digesta (dromedaries), 4th-stage larvae either in digesta or mucosae (cattle), or 4th-stage larvae in mucosae and few adults (sheep and goats). The prolificacy of female worms, indicative of the potential to contaminate pastures, was similar for all Haemonchus spp. in the rainy season. H. longistipes behave differently during the pre-rainy season as no increase of prolificacy could be demonstrated as observed in the other species. Traits of vulvar morphology are considered as markers of ecological adaptation and were studied. The knobbed and smooth female morphs (in equal proportions) were the most frequent in H. longistipes, the knobbed morph out-numbered the other morphs in H. placei, and all 3 morphs were present in sheep and goats with the linguiform form being predominant. Genetic characterization of the 3 species was performed by means of Random Amplified Polymorphic DNA (RAPD). Three groups were obtained from analysis of these data: 1 group with individuals of H. contortus, 1 group with individuals of H. placei, and 1 group with individuals of H. longistipes. This indicated that, although the 3 species were valid, H. contortus and H. placei were more similar. Intraspecific variability was 2-fold higher in H. contortus than in the 2 other species. The ecological, morphological and genetical studies showed that H. longistipes, H. placei and H. contortus could be arranged in increasing order of variability.

Dry areas: an example of seasonal evolution of helminth infection of sheep and goats in southern Mauritania

A total of 647 faecal egg counts and 53 necropsies were performed on sheep and goats originating from three sites of a Sahelian region of Mauritania (Gorgol) over a period of 2 years (1990-1992). Haemonchus contortus, Oesophagostomum columbianum and Stilesia globipunctata were the most prevalent species. The seasonal pattern was characterized by long survival of adults and high percentages of arrested fourth-stage larvae in the dry season, suggesting that two different strategies were used to survive from one rainy season to the next. Sheep and goats were equally infected, except for Stilesia globipunctata, which was found more often in sheep. The influence of age was limited, although kids and lambs born in the beginning of the dry season did not become infected until their first grazing in the rainy season.