Genotypic characterisation of monepantel resistance in historical and newly derived field strains of Teladorsagia circumcincta

Recent reports of monepantel (MPTL) resistance in UK field isolates of Teladorsagia circumcincta has highlighted the need for a better understanding of the mechanism of MPTL-resistance in order to preserve its anthelmintic efficacy in this economically important species. Nine discrete populations of T. circumcincta were genotypically characterised; three MPTL-susceptible isolates, three experimentally selected MPTL-resistant strains and three field derived populations. Full-length Tci-mptl-1 gene sequences were generated and comparisons between the MPTL-susceptible isolates, MPTL-resistant strains and one field isolate, showed that different putative MPTL-resistance conferring mutations were present in different resistant isolates. Truncated forms of the Tci-mptl-1 gene were also observed. The genetic variability of individual larvae, within and between populations, was examined using microsatellite analyses at 10 'neutral' loci (presumed to be unaffected by MPTL). Results confirmed that there was little background genetic variation between the populations, global FST <0.038. Polymorphisms present in exons 7 and 8 of Tci-mptl-1 enabled genotyping of individual larvae. A reduction in the number of genotypes was observed in all MPTL-resistant strains compared to the MPTL-susceptible strains that they were derived from, suggesting there was purifying selection at Tci-mptl-1 as a result of MPTL-treatment. The potential link between benzimidazole (BZ)-resistance and MPTL-resistance was examined by screening individual larvae for the presence of three SNPs associated with BZ-resistance in the β-tubulin isotype-1 gene. The majority of larvae were BZ-susceptible homozygotes at positions 167 and 198. Increased heterozygosity at position 200 was observed in the MPTL-resistant strains compared to their respective MPTL-susceptible population. There was no decrease in the occurrence of BZ-resistant genotypes in larvae from each population. These differences, in light of the purifying selection at this locus in all MPTL-resistant isolates, suggests that Tci-mptl-1 confers MPTL-resistance in T. circumcincta, as in Haemonchus contortus, but that different mutations in Tci-mptl-1 can confer resistance in different populations.

A New Species of Bidigiticauda (Nematoda: Strongylida) from the Bat Artibeus Planirostris (Chiroptera: Phyllostomidae) in the Atlantic Forest and a Molecular Phylogeny of the Molineid Bat Parasites

The nematode genus Bidigiticauda has 2 species (Bidigiticauda vivipara and Bidigiticauda embryophilum), which are parasites of bats from the Neotropical region. The present paper describes a new species of Bidigiticauda from a male Artibeus planirostris specimen collected in the Pratigi Environmental Protection Area in Bahia state, Brazil. The new species, Bidigiticauda serrafreirei n. sp., differs from B. embryophilum by having longer spicules, rays 5 and 6 arising from a common trunk and bifurcating in its first third, rays 3 and 4 emerging slightly separated from each other, and dorsal rays reaching the margin of the caudal bursa. The new species also differs from B. vivipara by the dorsal ray bifurcating at the extremity of the trunk. A molecular phylogenetic analysis was conducted to determine the evolutionary affinities of Bidigiticauda serrafreirei n. sp. within the Strongylida, which identified a clade that grouped Bidigiticauda with the other members of the Anoplostrongylinae. However, the molineid subfamilies did not group together, indicating that the family Molineidae is polyphyletic. Further analyses, which include additional taxa and genetic markers, should elucidate the complex relationships within the Molineidae, in particular its subfamilies and the evolution of the traits that define these groups.

First Evidence of Teladorsagia circumcincta Infection in Sheep from Egypt

Trichostrongylid nematodes are a common cause of gastroenteritis in sheep. Despite its worldwide distribution, Teladorsagia circumcincta has not been included in reports listing the various trichostrongyles infecting sheep from Egypt. Herein, we describe the presence of 2 T. circumcincta haplotypes infecting small ruminants from Egypt. For this study, fresh fecal samples were collected from 340 sheep and 115 goats reared at 5 districts in Dakahlia governorate and its surroundings, Egypt. Trichostrongyle eggs were harvested from the samples, and then subjected to DNA isolation and analysis. Polymerase chain reaction (PCR) amplification was carried out for the second internal transcribed spacer of ribosomal DNA (ITS2 rDNA). Purified PCR products of T. circumcincta were sequenced, and the revealed sequences were subjected to the nucleotide and phylogenetic analysis. A relatively high prevalence of trichostrongyles eggs was identified in sheep (33.2%) and a lower prevalence was found in goats (14.7%). Molecular analysis revealed, for the first time, 2 sheep herds from Egypt that were infected with T. circumcincta. Both infected herds were raised by the Bedouins in rural areas of El Mahalla El Kubra city. No T. circumcincta infections were found in any of the goats. Nucleotide sequence analysis revealed 2 haplotypes (Te1 and Te2) from 7 successfully sequenced samples (5 from the first and 2 from the second herd). Te1 was the major haplotype in both herds, and Te2 was retrieved from a single sample. Phylogenetic analysis displayed that the Te1 haplotype clustered with one from Cyprus, which might have been introduced to Egypt via goats imported from Cyprus due to a program to improve meat and milk production in Egypt. The present results could be beneficial in understanding the epidemiology of T. circumcincta and other trichostrongyles in Egypt, and have implementations in the effective control strategies used in this region.

Adaptations and phenotypic plasticity in developmental traits of Marshallagia marshalli

Despite the economic, social and ecological importance of the ostertagiine abomasal nematode Marshallagia marshalli, little is known about its life history traits and its adaptations to cope with environmental extremes. Conserved species-specific traits can act as exaptations that may enhance parasite fitness in changing environments. Using a series of experiments, we revealed several unique adaptations of the free-living stages of M. marshalli that differ from other ostertagiines. Eggs were isolated from the feces of bighorn sheep (Ovis canadensis) from the Canadian Rocky Mountains and were cultured at different temperatures and with different media. Hatching occurred primarily as L1s in an advanced stage of development, morphologically very similar to a L2. When cultured at 20 °C, however, 2.86% of eggs hatched as L3, with this phenomenon being significantly more common at higher temperatures, peaking at 30 °C with 28.95% of eggs hatching as L3s. After hatching, free-living larvae of M. marshalli did not feed nor grow as they matured from L1 to infective L3. These life history traits seem to be adaptations to cope with the extreme environmental conditions that Marshallagia faces across its extensive latitudinal distribution in North America and Eurasia. In order to refine the predictions of parasite dynamics under scenarios of a changing climate, basic life history traits and temperature-dependent phenotypic behaviour should be incorporated into models for parasite biology.

Zygocaulus nagoensis n. gen. and n. sp. (Trichostrongyloidea: Dictyocaulidae), a Peculiar Bursate Nematode Collected from an Alien Frog, Polypedates leucomystax, in Nago, Okinawa Island, Japan

A peculiar bursate nematode, Zygocaulus nagoensis n. gen. and n. sp. (Trichostrongyloidea: Dictyocaulidae: Mertensinematinae), was described from an alien frog, Polypedates leucomystax (Anura: Rhacophoridae), collected on Okinawa Island, Japan. It is related to Mertensinema and Borrellostrongylus, the only hitherto known genera of Mertensinematinae, but is readily distinguished from them by having only 2 pairs of lateral rays and simple distal ends of the dorsal ray branches.

Molecular marker sequences of cattle Cooperia species identify Cooperia spatulata as a morphotype of Cooperia punctata

The genus Cooperia includes important parasites of ruminants and currently contains 34 accepted species. However, even for those species infecting livestock, there is a considerable lack of molecular information and many species are only identifiable using subtle morphological traits. The present study aimed to provide molecular data to allow diagnosis of Cooperia species infecting cattle. Partial sequences of two mitochondrial (cytochrome oxidase 2, 12S rRNA gene) and two nuclear genes (isotype 1 β tubulin gene including two introns, internal transcribed spacers (ITS) were obtained from morphologically identified specimens of Cooperia pectinata, Cooperia punctata and Cooperia spatulata as well as from larvae of pure Cooperia oncophora and C. punctata laboratory isolates. Pairwise identity of ITS-2 sequences was very high and it was the only region able to identify a specimen as Cooperia sp. However, the ITS-2 was unreliable for diagnosis at the species level. All other marker sequences could not unequivocally be allocated to the genus Cooperia but allowed clear species identification with the exception of the pair C. punctata/C. spatulata for which no significant differences were found for any marker sequence. Maximum-likelihood phylogenetic analyses of individual genes as well as a multi-locus analysis covering all four sequences confirmed that specimen identified as C. spatulata were randomly distributed throughout the C. punctata cluster and formed no group of their own. In contrast, the other Cooperia species formed clearly separated and statistically supported clusters. These data indicate that C. spatulata is most likely only a morphotype of C. punctata and the name should be considered a synonym. Combinations of nuclear and mitochondrial markers should be used to identify morphotypes or cryptic species to benefit from excellent barcoding properties of the latter but allowing proper phylogenetic analyses and controlling for lineage sorting that might occur for mitochondrial genotypes within a species.

Diversity of gastrointestinal helminths in Dall's sheep and the negative association of the abomasal nematode, Marshallagia marshalli, with fitness indicators

Gastrointestinal helminths can have a detrimental effect on the fitness of wild ungulates. Arctic and Subarctic ecosystems are ideal for the study of host-parasite interactions due to the comparatively simple ecological interactions and limited confounding factors. We used a unique dataset assembled in the early seventies to study the diversity of gastrointestinal helminths and their effect on fitness indicators of Dall’s sheep, Ovis dalli dalli, in the Mackenzie Mountains, Northwest Territories, Canada. Parasite diversity included nine species, among which the abomasal nematode Marshallagia marshalli occurred with the highest prevalence and infection intensity. The intensity of M. marshalli increased with age and was negatively associated with body condition and pregnancy status in Dall’s sheep across all the analyses performed. The intensity of the intestinal whipworm, Trichuris schumakovitschi, decreased with age. No other parasites were significantly associated with age, body condition, or pregnancy. Our study suggests that M. marshalli might negatively influence fitness of adult female Dall’s sheep.

Host immunity, nutrition and coinfection alter longitudinal infection patterns of schistosomes in a free ranging African buffalo population

Schistosomes are trematode parasites of global importance, causing infections in millions of people, livestock, and wildlife. Most studies on schistosomiasis, involve human subjects; as such, there is a paucity of longitudinal studies investigating parasite dynamics in the absence of intervention. As a consequence, despite decades of research on schistosomiasis, our understanding of its ecology in natural host populations is centered around how environmental exposure and acquired immunity influence acquisition of parasites, while very little is known about the influence of host physiology, coinfection and clearance in the absence of drug treatment. We used a 4-year study in free-ranging African buffalo to investigate natural schistosome dynamics. We asked (i) what are the spatial and temporal patterns of schistosome infections; (ii) how do parasite burdens vary over time within individual hosts; and (iii) what host factors (immunological, physiological, co-infection) and environmental factors (season, location) explain patterns of schistosome acquisition and loss in buffalo? Schistosome infections were common among buffalo. Microgeographic structure explained some variation in parasite burdens among hosts, indicating transmission hotspots. Overall, parasite burdens ratcheted up over time; however, gains in schistosome abundance in the dry season were partially offset by losses in the wet season, with some hosts demonstrating complete clearance of infection. Variation among buffalo in schistosome loss was associated with immunologic and nutritional factors, as well as co-infection by the gastrointestinal helminth Cooperia fuelleborni. Our results demonstrate that schistosome infections are surprisingly dynamic in a free-living mammalian host population, and point to a role for host factors in driving variation in parasite clearance, but not parasite acquisition which is driven by seasonal changes and spatial habitat utilization. Our study illustrates the power of longitudinal studies for discovering mechanisms underlying parasite dynamics in individual animals and populations.

Abomasal dysfunction and cellular and mucin changes during infection of sheep with larval or adult Teladorsagia circumcincta

This is the first integrated study of the effects on gastric secretion, inflammation and fundic mucins after infection with L3 T. circumcincta and in the very early period following transplantation of adult worms. At 3 months-of-age, 20 Coopworth lambs were infected intraruminally with 35,000 L3; infected animals were killed on Days 5, 10, 15, 20 and 30 post-infection and 6 controls on either Day 0 or 30 post-infection. Another 15 Romney cross lambs received 10,000 adult worms at 4-5 months-of-age though surgically-implanted abomasal cannulae and were killed after 6, 12, 24 and 72 hours; uninfected controls were also killed at 72 hours. Blood was collected at regular intervals from all animals for measurement of serum gastrin and pepsinogen and abomasal fluid for pH measurement from cannulated sheep. Tissues collected at necropsy were fixed in Bouin's fluid for light microscopy, immunocytochemistry and mucin staining and in Karnovsky's fluid for electron microscopy. Nodules around glands containing developing larvae were seen on Day 5 p.i., but generalised effects on secretion occurred only after parasite emergence and within hours after transplantation of adult worms. After L3 infection, there were maximum worm burdens on Days 10-15 post-infection, together with peak tissue eosinophilia, inhibition of gastric acid secretion, hypergastrinaemia, hyperpepsinogenaemia, loss of parietal cells, enlarged gastric pits containing less mucin and increased numbers of mucous neck cells. After adult transplantation, serum pepsinogen was significantly increased after 9 hours and serum gastrin after 18 hours. Parallel changes in host tissues and the numbers of parasites in the abomasal lumen suggest that luminal parasites, but not those in the tissues, are key drivers of the pathophysiology and inflammatory response in animals exposed to parasites for the first time. These results are consistent with initiation of the host response by parasite chemicals diffusing across the surface epithelium, possibly aided by components of ES products which increased permeability. Parietal cells appear to be a key target, resulting in secondary increases in serum gastrin, pit elongation, loss of surface mucins and inhibition of chief cell maturation. Inflammation occurs in parallel, and could either cause the pathology or exacerbate the direct effects of ES products.

Differential expression of genes in fetal brain as a consequence of maternal protein deficiency and nematode infection

Maternal dietary protein deficiency and gastrointestinal nematode infection during early pregnancy have negative impacts on both maternal placental gene expression and fetal growth in the mouse. Here we used next-generation RNA sequencing to test our hypothesis that maternal protein deficiency and/or nematode infection also alter the expression of genes in the developing fetal brain. Outbred pregnant CD1 mice were used in a 2×2 design with two levels of dietary protein (24% versus 6%) and two levels of infection (repeated sham versus Heligmosomoides bakeri beginning at gestation day 5). Pregnant dams were euthanized on gestation day 18 to harvest the whole fetal brain. Four fetal brains from each treatment group were analyzed using RNA Hi-Seq sequencing and the differential expression of genes was determined by the edgeR package using NetworkAnalyst. In response to maternal H. bakeri infection, 96 genes (88 up-regulated and eight down-regulated) were differentially expressed in the fetal brain. Differentially expressed genes were involved in metabolic processes, developmental processes and the immune system according to the PANTHER classification system. Among the important biological functions identified, several up-regulated genes have known neurological functions including neuro-development (Gdf15, Ing4), neural differentiation (miRNA let-7), synaptic plasticity (via suppression of NF-κβ), neuro-inflammation (S100A8, S100A9) and glucose metabolism (Tnnt1, Atf3). However, in response to maternal protein deficiency, brain-specific serine protease (Prss22) was the only up-regulated gene and only one gene (Dynlt1a) responded to the interaction of maternal nematode infection and protein deficiency. In conclusion, maternal exposure to GI nematode infection from day 5 to 18 of pregnancy may influence developmental programming of the fetal brain.

Guerrerostrongylus marginalis n. sp. (Trichostrongyloidea: Heligmonellidae) from the Guianan arboreal mouse (Oecomys auyantepui) from French Guiana

Based on the number and arrangement of cuticular ridges and configuration of the dorsal ray, nematode specimens collected from the small intestine of eight Guianan arboreal mice, Oecomys auyantepui (Rodentia: Sigmodontinae), in French Guiana are herein described and characterized. Guerrerostrongylus marginalis n. sp. (Heligmosomoidea: Heligmonellidae) shows a synlophe consisting of more than 40 ridges and a unique bursal arrangement with ray 8 (externo-dorsal) extending to the edge of the bursal margin, and appearing more prominent than the dorsal ray. This bursal arrangement is common in members of Hassalstrongylus Durette-Desset, 1971, but uncommon in the other four species in Guerrerostrongylus Sutton & Durette-Desset, 1991. The placement of the new species in Guerrerostrongylus is based on the number and nature of cuticular ridges and the ray arrangement and symmetry of the caudal bursa. Diagnostic characteristics of Guerrerostrongylus marginalis n. sp. include the length of ray 8 relative to bursal margin, the relative size of the spicules and vestibule, and the number of eggs in the uterus. We propose an amendment to the generic diagnosis of Guerrerostrongylus to modify the characters of the long rays 6 (postero-lateral), rays 8 (externo-dorsal), and dorsal ray as diagnostic, since at least ray 6 appears to be short in two different species in the genus, namely G. ulysi Digiani, Notarnicola & Navone, 2012 and G. marginalis n. sp.

Selection for anthelmintic resistant Teladorsagia circumcincta in pre-weaned lambs by treating their dams with long-acting moxidectin injection

Administration of long-acting anthelmintics to pregnant ewes prior to lambing is a common practice in New Zealand. Today, most of these products contain macrocyclic lactone (ML) actives, which because of their lipophilic nature, are detectable in the milk of treated animals and in the plasma of their suckling offspring. This study was conducted to confirm the transfer of ML actives to lambs in the ewe's milk, and to assess whether this could result in selection for ML resistant nematodes in the lamb. Ninety, twin bearing Romney ewes were treated before lambing with a long-acting injectable formulation of moxidectin, a 100-day controlled release capsule (CRC) containing abamectin and albendazole, or remained untreated. After lambing, seven ewes from each treatment group were selected for uniformity of lambing date and, along with their twin lambs, relocated indoors. At intervals, all ewes and lambs were bled, and samples of ewe's milk were collected, for determination of drug concentrations. Commencing 4 weeks after birth all lambs were dosed weekly with 250 infective larvae (L3) of either an ML-susceptible or –resistant isolate of Teladorsagia circumcinta. At 12 weeks of age all lambs were slaughtered and their abomasa recovered for worm counts. Moxidectin was detected in the plasma of moxidectin-treated ewes until about 50 days after treatment and in their lambs until about day 60. Abamectin was detected in the plasma of CRC-treated ewes until the last sample on day 80 and in the plasma of their lambs until about day 60. Both actives were detectable in milk of treated ewes until day 80 after treatment. Establishment of resistant L3 was not different between the treatment groups but treatment of ewes with moxidectin reduced establishment of susceptible L3 by 70%, confirming the potential of drug transfer in milk to screen for ML-resistance in the suckling lamb.

•

Long-acting anthelmintics were administered to pregnant ewes.

•

Moxidectin and abamectin were detected in ewe's milk for >60 days.

•

Moxidectin and abamectin were detected in plasma of lambs for >60 days.

•

Abamectin treatment had not effect on establishment of larvae in the lambs.

•

Moxidectin treatment reduced establishment of susceptible, but not resistant larvae.

A new species of Torrestrongylus (Trichostrongylidae, Anoplostrongylinae) from Macrotus waterhousii (Chiroptera: Phyllostomidae) in Central Mexico

A new species of nematode, Torrestrongylus tetradorsalis n. sp., is described herein, based on specimens recovered from the small intestine of the leaf-nosed bat, Macrotus waterhousii, from the Biosphere Reserve "Sierra de Huautla" in the state of Morelos, Mexico. The new species is included in Torrestrongylus because it features a bursa of the type 3 - 2, a divided cephalic vesicle with an anterior half in the shape of an umbrella, and a posterior widened half. The new species can be distinguished from the only other congener T. torrei Pérez-Vigueras, 1935 by four key features: first, by the absence of cervical alae in both males and females; second, by the relatively longer second half of the cephalic cap; third, by the configuration of the dorsal ray, that does not have a medial terminal ray, and finally, by the structure of the spicules. This is the second species in the genus, previously known from bats of the families Phyllostomidae and Molossidae in Cuba, and now in Mexico.

Proteomic analysis of Mecistocirrus digitatus and Haemonchus contortus intestinal protein extracts and subsequent efficacy testing in a vaccine trial

BACKGROUND

Gastrointestinal nematode infections, such as Haemonchus contortus and Mecistocirrus digitatus, are ranked in the top twenty diseases affecting small-holder farmers' livestock, yet research into M. digitatus, which infects cattle and buffalo in Asia is limited. Intestine-derived native protein vaccines are effective against Haemonchus, yet the protective efficacy of intestine-derived M. digitatus proteins has yet to be determined.

METHODOLOGY/PRINCIPAL FINDINGS

A simplified protein extraction protocol (A) is described and compared to an established method (B) for protein extraction from H. contortus. Proteomic analysis of the H. contortus and M. digitatus protein extracts identified putative vaccine antigens including aminopeptidases (H11), zinc metallopeptidases, glutamate dehydrogenase, and apical gut membrane polyproteins. A vaccine trial compared the ability of the M. digitatus extract and two different H. contortus extracts to protect sheep against H. contortus challenge. Both Haemonchus fractions (A and B) were highly effective, reducing cumulative Faecal Egg Counts (FEC) by 99.19% and 99.89% and total worm burdens by 87.28% and 93.64% respectively, compared to the unvaccinated controls. There was no effect on H. contortus worm burdens following vaccination with the M. digitatus extract and the 28.2% reduction in cumulative FEC was not statistically significant. However, FEC were consistently lower in the M. digitatus extract vaccinates compared to the un-vaccinated controls from 25 days post-infection.

CONCLUSIONS/SIGNIFICANCE

Similar, antigenically cross-reactive proteins are found in H. contortus and M. digitatus; this is the first step towards developing a multivalent native vaccine against Haemonchus species and M. digitatus. The simplified protein extraction method could form the basis for a locally produced vaccine against H. contortus and, possibly M. digitatus, in regions where effective cold chains for vaccine distribution are limited. The application of such a vaccine in these regions would reduce the need for anthelmintic treatment and the resultant selection for anthelmintic resistant parasites.

Teladorsagia circumcincta antibodies in serum and milk samples in experimentally infected lactating ewes

The aim of this study was to evaluate the IgG activity in serum and milk samples of experimentally infected lactating ewes with the nematode Teladorsagia circumcincta as well as its relationship to the degree of infection. In a previous study 28 pregnant ewes were divided into two homogeneous groups, with high (H) and low (L) level of parasitism, respectively. Blood and milk samples were taken weekly after lambing until the end of the lactation, 126 days post-partum (pp). IgG against T. circumcincta were measured by means of an indirect ELISA. The kinetic of the immunoglubulins in serum samples showed a very low activity at the beginning but gradually increased throughout the lactation; H group showed higher values most of the sampled days than L group. Contrary, IgG in milk samples remained high during the first month pp, then decreased around 38% and by the end of the study rose again. Antibodies in both samples were correlated and especially during the second month of lactation (r=0.3; p<0.001). With the aim to correlate the immune response and the degree of infection we found an inverse relationship (r=-0.2; p<0.05) during the second month of lactation between eggs and IgG in serum. However the correlation with immunoglobulins in milk was positive, mainly, on the last third of lactation (r=0.2; p<0.01). As a conclusion, the individual detection of total IgG antibodies against T. circumcincta in lactating ewes is highly dependent on the stage of lactation. Therefore, these associations should be confirmed under field conditions.

Phylogenetic relationships of three species within the family Heligmonellidae (Nematoda; Heligmosomoidea) from Japanese rodents and a lagomorph based on the sequences of ribosomal DNA internal transcribed spacers, ITS-1 and ITS-2

Nematodes of the family Heligmonellidae (Heligmosomoidea; Trichostrongylina) reside in the digestive tracts of rodents and lagomorphs. Although this family contains large numbers of genera and species, genetic information on the Heligmonellidae is very limited. We collected and isolated adult worms of three species in Japan that belong to the family Heligmonellidae, namely Heligmonoides speciosus (Konno, 1963) Durette-Desset, 1970 (Hs) from Apodemus argenteus, Orientostrongylus ezoensis Tada, 1975 (Oe) from Rattus norvegicus and Lagostrongylus leporis (Schulz, 1931) (Ll) from Pentalagus furnessi, and sequenced the entire internal transcribed spacer regions, ITS-1 and ITS-2 of ribosomal DNA. ITS-1 of Hs, Oe and Ll was 426, 468 and 449 bp in length, and had a G+C content of about 41, 41 and 37 %, respectively. ITS-2 of Hs, Oe and Ll was 297, 319 and 276 bp in length and had a G+C content of about 38, 40 and 28%, respectively. The data of Hs, Oe and Ll were compared with those of two other known species within the family Heligmonellidae, Calorinensis minutus (Dujardin, 1845) (Cm) and Nippostrogylus brasiliensis (Travassos, 1914) (Nb), and with those of two species of Heligmosomidae (Heligmosomoidea), Heligmosomoides polygyrus bakeri and Ohbayashinema erbaevae. Phylogenetic analysis placed Hs, Oe and Ll in the same clade with Cm and Nb, forming a Heligmonellidae branch in both ITS-1 and ITS-2, separate from the Heligmosomoidea branch. These results demonstrated that the ITS-1 and ITS-2 sequences are useful for differentiating the Heligmonellidae nematode species. This study is the first to describe the ITS-1 and ITS-2 sequences of Hs, Oe and Ll.

Pathological lesions in European bison (Bison bonasus) with infestation by Ashworthius sidemi (Nematoda, Trichostrongylidae)

Asworthius sidemi Schulz, 1933 is a blood sucking gastrointestinal nematode, primarily typical for Asiatic deer. It was found for the first time in Poland in European bison in 1997. To estimate the level of invasion of A. sidemi and histopathological changes connected with the presence of the parasite in the years 2004-2007 parasitological and histopathological examinations of 54 European bison from Białowieza Forest were carried out. Parasitological examination was carried out by the sedimentation method and A. sidemi were diagnosed under a binocular microscope. Samples for histological examination were collected from the abomasum and duodenum walls as well as from regional lymph nodes. Tissue samples were then fixed with 10% buffered formalin, embedded in paraffin, cut in to 5 microm thick sections and stained with hematoxylin and eosin (H&E). Parasitological examinations showed the presence of fourth stage larvae and juvenile forms of A. sidemi. The maximal intensity of invasion rose systematically from 4470 A. sidemi nematodes in 2004/2005 to 44310 in 2006/2007. Histopathological examinations showed infiltrations of inflammatory cells in the walls of abomasa and duodena at various levels of intensity (mainly lymphoid cells and eosinophils), hyperemiae, oedemae and lesions of mucosa and proliferation of lymphatic follicles. In individual cases of dysplasia of epithelial cells, atrophy or hyperplasia of glands and the presence of parasites in the lumen or walls of the abomasum/duodenum were observed. In one case, parasitic nodules were found. In regional lymph nodes proliferation of lymphatic follicles, presence of eosinophils and desolation of reproduction centers were observed. Intensification of histopathological changes was connected to a considerable degree with the developmental stage of A. sidemi as shown by parasitological examination.

[Sheep trichostrongylidosis in Van province]

This study was performed in the Van Municipality Slaughterhouse from January to December 2001. Abomasums and small intestines from a total of 104 sheep were transported to the parasitology laboratory of the Veterinary Faculty of Yüzüncü Yil University for parasitological examination. The abomasums and small intestines of the animals were opened with appropriate technique in the laboratory, and male nematodes were collected from the contents of the abomasums and small intestines using a sampling method, and then these parasites were identified. Gastrointestinal nematodes were encountered in 87.5% out of 104 sheep. Marshallagia marshalli (85%), Teladorsagia circumcincta (75%), Nematodirus oiratianus (75%), N. spathiger (65%), Haemonchus contortus (40%), Tel. occidentalis (36%), Trichostrongylus axei (33%), N. abnormalis (19%) and T. probolurus (19%), Tel. davtiani (15%), Tel. trifurcate (10%), and Camelostrongylus mentulatus (1%) were detected. Among the parasites, the species encountered most often were Tel. circumcincta (45.23%) in abomasums and N.oiratianus (65.73%) in small intestines. The highest rate of parasites in both abomasums and small intestines occurred in August, September and October. It was found that the young animals have a parasite density higher than the adults and the females have parasite density higher than the males.

Ashworthius sidemi (Nematoda, Trichostrongylidae) in wild ruminants in Białowieza Forest

Between 2003-2007, abomasa of 91 European bison (Bison bonasus), 4 red deer (Cervus elaphus) and 2 roe deer (Capreolus capreolus) shot in the Białowieza Primeval Forest (Poland) were examined for worms presence. All the animals examined were infected with nematodes A. sidemi with an exception of one bison, that was shot in year 2003. There was much higher average intensity of invasion in bison (5529), than in red deer (85) and in roe deer (1837). The animals were shot in a period from December to March, and the nematodes found in them were fourth stage larvae and immature adult specimens. In the following years of examinations, a gradual increase in average intensity of infection was observed. In 2007, it reached in bison 10814 nematodes. Maximum intensity of invasion was found in this year as well and it reached 44310 nematodes in one bison. Pathological changes such as an oedema, hyperaemia and effusion in the abomasum and duodenum mucosa were most clearly seen in the calves that were highly infected. These changes probably lead to chronic diarrhoea, deterioration and deaths of young animals.

Parasite loss and inhibited development of Teladorsagia circumcincta in relation to the kinetics of the local IgA response in sheep

Groups of yearling sheep, which had been trickle infected with Teladorsagia circumcincta for 8 weeks and then drenched, were challenged with 50 000 T. circumcincta larvae together with groups of worm-free controls. Fewer parasites and a greater proportion of early fourth stage larvae were recovered from previously infected sheep compared to controls. Worm loss and arrested development were evident by 5 days after challenge whereas growth retardation of developing worms was observed by day 10. In the previously infected sheep a secondary IgA response was observed in the efferent gastric lymph from 5 days post-infection. Western blot analysis showed the lymph IgA to be predominantly dimeric and nonsecretory in nature and that the somatic antigens recognized were predominantly in the 100-250 kDa range. The concentration of IgA in lymph was always higher than in blood and in the previously infected sheep increased fivefold 8 days post-challenge in contrast to blood where IgA levels were unchanged. The timing of the response suggested that it occurred too late to have been the cause of worm loss or arrested development, though it may have retarded the growth of developing parasites.

Individual administration of three tanniferous forage plants to lambs artificially infected with Haemonchus contortus and Cooperia curticei

We investigated direct anthelmintic effects associated with the feeding of fresh tanniferous forages against established populations of Haemonchus contortus and Cooperia curticei in lambs. Twenty-four parasite naive lambs were inoculated with a single dose of infective larvae of these two parasites 27 days prior to the start of the feeding experiment. Lambs were individually fed with either chicory (Cichorium intybus), birdsfoot trefoil (Lotus corniculatus), sainfoin (Onobrychis viciifolia) or a ryegrass/lucerne mixture (control) for 17 days. Animals where then united to one flock and subjected to control feeding for another 11 days to test the sustainability of potentially lowered egg excretion generated by tanniferous forage feeding. When compared to the control, administration of all tanniferous forages was associated with significant reductions of total daily faecal egg output specific to H. contortus (chicory: 89%; birdsfoot trefoil: 63%; sainfoin: 63%; all tests P<0.05) and a tendency of reduced H. contortus worm burden (chicory: 15%; birdsfoot trefoil: 49% and sainfoin: 35% reduction). Irrespective of the condensed tannin (CT) containing fodder, no anthelmintic effects were found against C. curticei. Cessation of CT-feeding followed by non-CT control feeding did not result in a re-emergence of faecal egg counts based on faecal dry matter (FECDM) in any group, suggesting that egg output reductions are sustainable. The moderate to high concentrations of CTs in birdsfoot trefoil (15.2 g CTs kg(-1) dry matter (DM)) and sainfoin (26.1 g CTs kg(-1) DM) were compatible with the hypothesis that the antiparasitic effect of these forages is caused by their content of CTs. For chicory (3 g CTs kg(-1) DM), however, other secondary metabolites need to be considered. Overall, birdsfoot trefoil and in particular sainfoin seem promising candidates in contributing to an integrated control strategy against H. contortus not only by mitigating parasite related health disturbances of the host but also by a sustained reduction of pasture contamination.

Some observations on immunologically mediated inhibited Teladorsagia circumcincta and their subsequent resumption of development in sheep

Two similar experiments were conducted with groups of yearling sheep which had been trickle infected with Teladorsagia circumcincta for 6 weeks, treated with anthelmintic then challenged with a single dose of 50,000 larvae. Ten days after challenge these sheep contained significantly fewer worms and a significantly higher proportion of arrested early fourth stage larvae than controls which had not received the trickle infection. However, by 19 or 23 days after challenge most of the arrested worms had resumed development, a process which was accelerated in a group treated with corticosteroids. It was concluded that under these conditions arrested development of Teladorsagia was a short-lived, immunologically mediated phenomenon which could be reversed by immuno-suppressing the sheep.

Trichostrongylina (Nematoda) from Malagasy Muridae. III--description of a new species of Heligmonoides Baylis, 1928 (Heligmonellidae) parasitic in Mus musculus

Heligmonoides variabilis n. sp. (Heligmosomoidea, Nippostrongylinae) a parasite of Mus musculus from Madagascar is related to H. afghanus (Tenora, 1969), H. ikeharai Hasegawa, 1990 and H. josephi (Wertheim & Durette-Desset, 1976), all having the dorsal ray divided anterior to the arising of rays 8. H. ikeharai a parasite of Tokudaia muenninki (Muridae) from Japan is the most closely related species with rays 8 arising at mid-length along the dorsal ray. It is differentiated from the new species by very long spicules (almost half of body length) and by the length of the vestibule (almost one millimeter). A new definition of the genus Heligmonoides Baylis, 1928 is proposed with a dichotomic key of the species. The biogeographic distribution and the host spectrum of the genus are described.

Resistance of trichostrongyles to benzimidazoles in Italy: a first report in a goat farm with multiple and repeated introductions

Anthelmintic resistance is widely distributed in small ruminants throughout the world. The extension of resistance seems lower in southern European countries and has not been reported previously in Italy. In the present study, resistance to benzimidazoles, levamisole and ivermectin was evaluated in a multi-breed goat farm of southern Italy. The farm had a history of repeated goat introductions from other flocks and a moderate regimen of anthelmintic treatments using alternatively the three above-mentioned drugs. Resistance of gastrointestinal strongyles was studied on the basis of faecal egg counts, egg hatch assay and necropsies. Resistance to anthelmintics was evidenced for benzimidazoles only, and Trichostrongylus colubriformis was the only resistant strongyle species. Single drug and single species resistance suggest that resistance is on its beginning and that measures for reducing the spread of resistance are of interest and should be promoted.

Histopathological changes during experimental infections of calves withCooperia punctata

Eleven male two-month-old Holstein calves were used to determine the pathological changes induced by aCooperia punctatainfection. After weaning, ten calves received a single oral dose of 45,000C. punctatainfective larvae. One calf remained as a non-infected control. Groups of two calves were killed on days 7, 14, 21, 28 and 35 post-infection (p.i.) for determination of worm burdens and histopathological evaluation. The small intestine was sub-divided into three sections of approximately equal length, and representative samples of mucosa were fixed in 10% formalin, cut, and stained with haematoxylin-eosin. Samples of intestinal contents and mucosal digests were taken and fixed in 10% formalin for an estimation of total worm burdens. An increase in the number of adult parasites and a decrease in the number of larvae were observed with time (P<0.001). A higher concentration of worms was found in the first segment of the small intestine during the five weeks of observation. Histology showed larvae in the intestinal mucosa on day 7 p.i., with a discrete increase in the cellular response. Adult worms and a marked cellular infiltrate with eosinophils and neutrophils were present on day 21 p.i., and these persisted until day 35 p.i. Microcysts resulting from worm destruction were observed from day 21 p.i.

The effect of weather on the occurrence and magnitude of periparturient rise in trichostronglyid nematode egg output in Dorper ewes in a semi-arid area of Kajiado District of Kenya

An investigation was carried out to assess the effects of weather on the occurrence and magnitude of the periparturient rise (PPR) in trichostrongylid nematode egg output in breeding Dorper ewes. The study was conducted over three breeding seasons on a ranch in the semi-arid area of Kajiado District in Kenya between June 1999 and December 2001. During each breeding season 20 ewes randomly selected from the breeding stock and 20 others selected from the unmated yearlings were monitored for faecal strongyle egg counts every 3 weeks. The lambing seasons were timed to coincide with the onset of the short rains (October-November 1999), the mid-short rains (November-December 2000) and the end of the dry season (September-October 2001). In each season higher egg outputs were recorded in the peri-parturient ewes compared to the unmated yearlings. The highest PPR occurred in September 2001, when lambing coincided with the end of the dry season, possibly as a result of maturation of hypobiotic larvae. The lowest PPR occurred in November 2000 when the onset of lambing coincided with the mid-short rains, possibly owing to low pasture infectivity associated with a long dry spell between January and October of the same year. The results of this study indicate that PPR occurred when lambing coincided with both the wet and the dry seasons. However, the magnitude was greatly influenced by the season when lambing occurred. It was also influenced by resumption of development of hypobiotic larvae and the nutritional status of the ewes. Not only should control of gastrointestinal nematode parasites in this area aim at preventing the occurrence of PPR by treating ewes 2-3 weeks before they are to lamb and during lactation, but the anthelmintic used must also eliminate hypobiotic larvae. In addition, the animals must be given supplementary feeding during this period.

[Some biochemical parameters in sheep infected with endoparasites (Fasciola spp., Dicrocoelium dendriticum, hydatid cysts, Trichostrongylidae and Protostrongylidae)]

This study was performed in order to investigate the variations of some blood biochemical parameters as well as the levels of Vitamin. B(12) and some macro elements in sheep infected with endoparasites. The blood samples were taken from the sheep that were to be slaughtered in the Van Municipality Slaughterhouse while the stool samples were taken after the slaughtering of the same animals. The postmortem examinations were made to investigate for the presence of Fasciola spp., D. dendriticum and cyst hydatid infections. The stool samples were examined helminthologically using native, sedimentation, flotation and Baermann-Wetzel methods. The control group was composed of animals not showing any internal organ parasites or parasites in the stool examination. Following the macroscopic and the stool examination, the animals found to have the same type of parasites were considered to be the study group. According to the analyses performed on the animals, the levels of total protein (in Trichostrongylidae, hydatid cysts), globulin, amylase, chlorine, and Vit.B(12) were found to be increased significantly, while the levels of albumin, magnesium, and phosphorus were found to be decreased significantly. The other parameters analyzed were not significant statistically between the groups.

Population genetic analysis of the ovine parasitic nematode Teladorsagia circumcincta and evidence for a cryptic species

An understanding of genetic variation in parasite populations, and how it is partitioned, is required to underpin many areas of basic and applied research. Population genetic studies on parasitic nematode populations are still in their infancy and have been dominated by the use of single locus markers. We have used a panel of five microsatellite markers to undertake a genetic study of a number of field and laboratory populations of Teladorsagia circumcincta. High levels of polymorphism were seen in all the populations examined with the majority of diversity being within rather than between populations. There was no detectable genetic differentiation between the UK populations examined although they included both laboratory passaged and field isolates derived from different geographical regions and host species. This broadly supports previous mtDNA sequence diversity studies of this parasite in the UK and USA. However, some between-population genetic differentiation was apparent when several populations from French goats and a laboratory population from New Zealand were examined. Most notably, a population from a French goat farm, which has previously been suggested to contain a cryptic species, showed very high levels of genetic differentiation from all the other populations. Analysis of multi-locus genotypes suggested the presence of two sympatric parasite populations on this farm with little or no gene flow between them. This supports the hypothesis that parasites currently defined as T. circumcincta by routine morphological criteria comprise more than a single species.

Effect of sainfoin (Onobrychis viciifolia) silage and hay on established populations of Haemonchus contortus and Cooperia curticei in lambs

The objective of the study was to examine the effect of dried and ensiled sainfoin (Onobrychis viciifolia) on established populations of Haemonchus contortus (abomasum) and Cooperia curticei (small intestine) in lambs under controlled conditions. Twenty-four parasite naïve lambs were inoculated with a single dose of infective larvae of these parasites 28 days prior to the start of the feeding experiment. Twenty-four days post-infection, 4 days prior to the start of the feeding experiment, animals were allocated to four groups according to egg excretion, live weight and sex. Groups A and B received sainfoin hay and control hay, respectively, for 16 days. Groups C and D were fed on sainfoin silage or control silage for the same period. Feeds were offered ad libitum and on the basis of daily refusals were supplemented with concentrate in order to make them isoproteic and isoenergetic. Individual faecal egg counts on a dry matter basis (FECDM) were performed every 3-4 days and faecal cultures and packed cell volume (PCV) measurements were done weekly. After 16 days of experimental feeding, all animals were slaughtered and adult worm populations were determined. The consumption of conserved sainfoin was associated with a reduction of adult H. contortus (47% in the case of hay, P<0.05; 49% in the case of silage, P=0.075) but had little effect on adult C. curticei. Compared to the controls, H. contortus specific FECDM was reduced by 58% (P<0.01) in the sainfoin hay group and by 48% (P=0.075) in the sainfoin silage group. For both sainfoin feeds FECDM specific to C. curticei were significantly decreased when compared to the control feeds (hay 81% and silage 74%, both tests P<0.001). Our data suggest that different mechanisms were responsible for the reduction in FECDM in response to feeding tanniferous fodder. For H. contortus, the decrease seemed to be due to a nematocidal effect towards adult H. contortus. In contrast for C. curticei, the reduction in FECDM appeared to be a result of a reduced per capita fecundity. For both, hay and silage, an antiparasitic effect could be shown, offering promising perspectives for the use of conserved tanniferous fodder as a complementary control approach against GIN.

Innovative restriction site created PCR-RFLP for detection of benzimidazole resistance in Teladorsagia circumcincta

Benzimidazole compounds, especially albendazole, are the most commonly used anthelmintics for deworming of small ruminants in Iran. It is believed that the therapeutic effects of the benzimidazoles (BZs) come through their binding capacity to the beta-tubulin isotype 1. Substitution of phenylalanine to tyrosine at position 200 of this polypeptide confers resistance to BZs. Several investigators developed different biological- and molecular-based techniques to demonstrate the occurrence of resistance in helminthes against BZs. To address the determination of resistance at position 200 of beta-tubulin isotype 1, we developed an innovative restriction site created polymerase chain reaction-restriction fragment length polymorphism, in which nucleotide A at the position of 637 upstream flanked by the first two coding sequences of the phenylalanine (TT) triplet was substituted through the nucleotide G. The introduced modification in forward primer (UTvet MF-primer) leads to the creation of restriction site (AACGTT) for PSP1. Therefore, in the case of normal allele only, PSP1 can cut the corresponding PCR product. In the first step, the genomic DNA was isolated from each single Teladorsagia circumcincta collected either from the abomasa of untreated (n = 35) or of 5 mg/kg BW 2.5% albendazole suspension-treated (n = 40) sheep. It was amplified with the primer pair, creating PCR product of 403 bp in length. In the second step, the PCR product was extracted from agarose gel and amplified with the modified forward primer (UTvet MF-primer) and the same reverse primer as in step 1, creating a PCR product of 222 bp. The PCR product was then cut with PSP1 to obtain in the case of normal allele two DNA products (183 and 39 bp). Eight of the 35 worms collected from the untreated sheep were BZ(SS) homozygotes, and the rest (27) were BZ(RS) heterozygotes. In our preliminary experiment, we could not find a BZ(RR) homozygote form within the examined samples. Five out of 40 worms collected from the albendazole-treated sheep were BZ(RR) homozygotes, whereas the rest (35) were BZ(RS) heterozygotes. No BZ(SS) homozygote form was detected within this group.

[Biology of gastrointestinal nematodes of ruminants]

The development and survival of free-living stages of gastro-intestinal nematodes of small ruminants are influenced by several abiotic and biotic factors. Within the abiotic factors, most important are the environmental temperature and humidity. They regulate the development of larvae from eggs dispersed on the pasture by the animals faeces. Each parasite species that infect ruminants requires a different time to development, depending on temperature and humidity. Among trichostrongylids, Ostertagia, Teladorsagia and Nematodirus show a strong adaptation to low temperatures. Nematodirus larvae are able to survive to winter inside the egg shell. Temperature and humidity influence the distribution and survival of larvae on pasture. The larval third stage can migrate from faeces to pasture vegetation and they accumulate at the basis of vegetation where stay during the day or in the soil to avoid the desiccation. The forage species affects the migration of larvae on herbage too. Many biological factors contribute to disperse the larvae on the pasture. Dung burying beetles, coprophagous beetles and earthworms can greatly reduce the larvae of some trichostrongylids on pasture. They contribute to the spread of the faecal material on the pasture and allow the larval death as a consequence of drying.

[Physiopathological mechanisms of abomasal Trichostrongylidae infections in small ruminants]

Abomasal Trichostrongylidae infections are still today an important cause of scarce performances in small ruminants, mainly when bred in extensive systems. Although morpho-biology, symptomatology, prophylaxis and therapy of these infections are well known, other, such as physiopathology, are less investigated. The aim of the present note is to review the more important physiopathogenetic mechanisms of abomasal Trichostrongylidae infections, with special emphasis to Haemonchus spp. and Teladorsagia spp. The parasitic anorexia due to the action of gastrin, the defects of digestion due to hypocloridia, the scarce intestinal absorption and anaemia caused by H. contortus are discussed. Furthermore, the effects of hypersensitivity sometimes caused by these abomasal nematodes are examined. A better knowledge of physiopathological mechanisms can represent an important factor to understand the relationships between host and parasite, useful to set up new diagnostic techniques or new therapeutic and prophylactic protocols for sanitary education and control plans of these important and widespread parasitic infections.

A new species of Sciurodendrium (Nematoda: Heligmonellidae) in Sciurus aureogaster (Rodentia: Sciuridae) from Morelos, Mexico

Sciurodendrium bravohollisae n. sp. (Heligmonellidae) is described as an intestinal parasite of 2 squirrels, Sciurus aureogaster Cuvier, 1829, collected from Los Robles, Municipio de Tlalnepantla, Morelos State, Mexico. The new species differs from all other congeners in possessing a very well-developed and sacciform genital cone. This is the seventh species described for the genus and the first one recorded in Mexico.

Eosinophil and IgA responses in sheep infected with Teladorsagia circumcincta

Infections of sheep with the gastrointestinal nematode Teladorsagia circumcincta are characterised by increased concentrations of IgA, eosinophilia and mastocytosis but the interactions between these immune responses are unclear. We investigated the kinetics of the parasite-specific IgA and eosinophil responses in controlled infections in lambs to determine if there were any associations with subsequent worm growth and survival. IgA and eosinophil responses had very similar kinetics and variation in both responses accounted for more of the variation in adult worm length than either trait alone suggesting that IgA and eosinophils interact in regulating the growth of T. circumcincta. Curiously, those animals with higher peak eosinophil responses had longer worms at slaughter emphasising the intriguing complexity of the immune responses to these parasitic infections.

The effects of birdsfoot trefoil (Lotus corniculatus) and chicory (Cichorium intybus) when compared with perennial ryegrass (Lolium perenne) on ovine gastrointestinal parasite development, survival and migration

Two experiments were conducted to investigate the effects of birdsfoot trefoil and chicory on parasitic nematode development, survival and migration when compared with perennial ryegrass. In experiment one, sheep faeces, containing 10,385 Cooperia curticei eggs were added to 25 cm diameter pots containing birdsfoot trefoil, chicory or ryegrass, and the pots maintained under optimal conditions for nematode parasite development. Replicate pots of each forage type were destructively sampled on day 8, 16, 20, 28 and 37 to collect the nematode larvae. When forages were compared on a dry matter basis, by day 16 there were 31% and 19% fewer larvae on birdsfoot trefoil and chicory than on ryegrass, respectively (P<0.01). In the second experiment, replicate 1m(2) field plots of birdsfoot trefoil, chicory and ryegrass were sub-sampled on day 14, 21, 35 and 49 for larval counts following the application of sheep faeces containing 585,000 Teladorsagia circumcincta eggs to each plot on day 0. Results showed there were a minimum of 58% and 63% fewer infective stage parasitic larvae on birdsfoot trefoil and chicory, respectively, compared with ryegrass on day 14 and 35 when forages were compared on a forage dry matter, plot area sampled and leaf area basis (P<0.01). Overall, these results indicate that the number of infective stage larvae on birdsfoot trefoil and chicory pasture was reduced by the effect of their sward structure on the development/survival/migration of ovine parasitic nematodes. These effects may be one of the ways in which these forages may affect parasitic infections in grazing livestock.

[Case report: Libyostrongylus douglassii-associated proventriculitis in ostriches in Germany]

Cases of Libyostrongylus douglassii-associated proventriculitis in an adult female ostrich and two ostrich chicks occurring on two farms in different federal states of Germany are described. The adult bird was recently bought and kept under quarantaine conditions without contact to other animals of the herd. Without developing clinical signs of illness, the animal died. At necropsy, typical lesions of wireworm infection were found. The lining of the stomach had a moth-eaten appearance. Massive amounts of adult stages of trichostrongyloid nematodes were diagnosed in histological specimens of the proventricular mucosa and under the koilin layer of the ventriculus. The worms were isolated from the proventriculus and identified as L. douglassii. The feces of the bird contained high amounts of typical eggs of the worms with a medium size of approximately 70 x 40 microm. A polyphasic degeneration of heart and skeletal muscle was diagnosed in addition to the wireworm infection and interpreted to be a result of a malnutrition (Vit. E-/selenium deficiency). The ostrich chicks were reared on another farm and submitted for necropsy because of high mortality (8 out of 12 chicks died). A massive invasion of the proventricular mucosa with L. douglassi was macroscopically and histologically detected at necropsy of the anemic birds.

Demonstration of Ollulanus tricuspis in the Stomach of Domestic Cats by Biopsy

Ollulanus tricuspis is a small nematode of the family Ollulanidae, found in the stomach of domestic cats and other felids. Of 131 gastric biopsy samples collected at endoscopic examination, four were shown to contain the parasite. Vomiting was the main presenting sign in three cats and weight loss in the fourth. The stomachs were grossly normal on endoscopic examination. Chronic gastritis was observed histologically in two cases, while the remaining cases were microscopically normal. The significance of the parasite remained undetermined. To our knowledge, this is the first report of O. tricuspis infection in domestic cats in which the diagnosis was made by examining routine endoscopic biopsy samples.

Mathematical models to assess strategies for the control of gastrointestinal roundworms in cattle 2. Validation

A computer model of the population biology of Ostertagia ostertagi in young cattle and the effect of the parasite on animal growth has been constructed. It was validated against results from field trials where worm populations and rate of growth of cattle treated with anthelmintics were compared to similar groups of untreated animals. A close correlation between observed and predicted values for faecal egg and pasture larval counts was seen in the cattle which had been treated with an oxfendazole pulse release bolus at turnout. Timings and peak values were less accurately predicted in the untreated cattle. Although predictions for live weight gain during the grazing season indicated that the model may be overestimating the potential growth rate of cattle, it is considered that the model provides a suitable tool for comparing the effectiveness of different worming programmes under farm conditions. The computer simulation also allowed examination of the underlying influences and interactions between parasitological factors, such as numbers of immature and adult worms, and animal and pasture factors, such as sward height, grass consumption and feed conversion, in the parasite's influence on animal performance.

Further characterisation of a triple resistant field isolate of Teladorsagia from a Scottish lowland sheep farm

Anthelmintic efficacies against juvenile developing populations of Teladorsagia species that were known to be resistant to anthelmintics from all three broad spectrum families were examined using a controlled efficacy test. Fenbendazole (FBZ), levamisole (LEV), ivermectin (IVM), combinations of these anthelmintics and moxidectin (MOX) were assessed in parasite naïve lambs artificially infected with 8,000 third stage larvae (Tci5) and treated orally 8-day post-infection with the compounds at the manufacturers recommended dose rates, FBZ, 5 mg/kg body weight (BW); LEV, 7.5 mg/kg BW; IVM, 0.2 mg/kg BW; MOX (0.2 mg/kg BW). The lambs were slaughtered 14-day post-treatment. The arithmetic mean worm burden reductions resulting from oral treatments with FBZ; IVM; LEV; FBZ+IVM; FBZ+LEV; FBZ, LEV+IVM or MOX were 36%, 82%, 38%, 86%, 60%, 88% and 97%, respectively. The results illustrate that combination treatments showed improved efficacies against the juvenile population compared to individually administered treatments but that these improvements were not wholly effective. Moxidectin was the only treatment that was over 95% effective, though caution should be noted when advising the use of MOX prophylactically since 3% of the infection still survived this treatment. Treatments directed at juvenile stages of Tci5 were less effective, with the exception of IVM, compared to a similar trial using Tci5 where the same treatments were directed against a predominantly adult population. No interaction was detected comparing the timings of treatments and its effectiveness with the exception of IVM (two-way ANOVA, p < 0.05). These findings suggest that, on the whole, the selection processes for anthelmintic resistance (AR) may occur at an early stage of development within the parasites, having severe implications for the early detection of AR.

Comparing different formulae to test for gastrointestinal nematode resistance to benzimidazoles in smallholder goat farms in Mexico

The objective was to examine the coincidence in the prevalence of benzimidazole (Bz) resistance in smallholder goat herds, as determined by three average-based and two individually-based faecal egg count reduction (FECR) tests. Nineteen smallholder goat herds with more than 30 animals were selected from 84 herds in Yucatan. Animals shedding 150 eggs/g of faeces (EPG) on day zero were randomly divided into two groups. The control group did not receive treatment and the treated group received fenbendazole (10mg/kg body weight per os). Feed was withdrawn for 16 h before treatment. Ten days after treatment, both groups were sampled to determine their FEC. Faecal cultures and identification of infective larvae were performed for estimating the proportions of genera of gastrointestinal nematodes (GIN) present. Presence of resistant GIN was determined with three different average-based FECR (FECR(1), FECR(2) and FECR(3)) and two individually-based FECR (iFECR(1) and iFECR(2)). The prevalence of herds with Bz resistant nematodes (and 95% confidence interval (95% CI)) was calculated using each formula. Coincidence among formulae was estimated with Kappa values. The prevalence (+/- 95% CI) of Bz resistance calculated with FECR(1) (57.89 +/- 22.20) had a high coincidence with iFECR(1) and iFECR(2) (Kappa values of 0.86 and 0.79, respectively). The prevalence with FECR(2) (31.58 +/- 20.90) and FECR(3) (21.05 +/- 18.33) had a low coincidence with FECR(1) (Kappa < 0.50). Trichostrongylids found on Bz resistant farms were mainly Haemonchus spp., however, some Trichostrongylus spp. and Oesophagostomum spp. were found too. The high coincidence between the standard average-based FECR(1) and the individually based formulae is encouraging and may suggest that either formula could be applied to smallholder farmers. Further laboratory studies are needed to confirm the resistance status in the herds.

The relationship between responsiveness against gastrointestinal nematodes in lambs and the numbers of circulating IgE-bearing cells

The objective of this study was to determine if any relationship exists between responsiveness against gastrointestinal nematodes (GI) in lambs and circulating IgE-bearing cells. Scottish Blackface lambs that were grazing on pasture infected with Teladorsagia circumcincta (T. circumcincta) were ranked in order of their cumulative resistance to nematode infection as determined by their faecal egg counts (FECs) from material taken throughout the grazing season. The 10 lambs that had the lowest egg count rankings termed "responders" and the 10 lambs that had the highest egg count rankings termed "non-responders", were selected using data from the whole season or the middle or end of the grazing season. The number of circulating IgE-bearing cells present in the selected responder and non-responder lambs was investigated. The study was followed for two grazing seasons. Results showed that there were higher numbers of circulating IgE-bearing cells in the blood of responder lambs when compared to non-responders in the lambs selected from the middle of the season during both grazing seasons. A significant difference in the number of these IgE-bearing cells in responder and non-responder lambs was also demonstrated at the last two time points (p<0.05) of the initial grazing season. FACS analysis confirmed that IgE-bearing cells were found predominantly among lymphocytes/monocytes. The present study provides further evidence for an active role for IgE antibody in nematode immunity, and suggests that these circulating IgE-bearing cells might serve as additional markers for selecting animals that are responsive against T. circumcincta infections in lambs.

Variation among faecal egg counts following natural nematode infection in Scottish Blackface lambs

Faecal egg counts were examined in 2 flocks of naturally infected Scottish Blackface sheep in southern and central Scotland. The distribution of mean counts was right skewed and similar to a gamma distribution. The counts varied with month, with mean counts rising from May to July, then falling but rising again in October, although data within each year did not always show such a clear pattern. There was no significant difference in mean egg count between the 2 farms examined. The distribution of egg count variances was also right skewed and conformed to a gamma distribution. There was a strong relationship between the mean and the variance for each population, implying that variation among populations in variances largely mirrored variation in mean egg counts. Populations with high mean egg counts and variances did not necessarily have more adult nematodes but had a greater number of adult nematodes from species other than Teladorsagia circumcincta, particularly Cooperia spp., Trichostrongylus axei and Trichostrongylus vitrinus. The contribution of different parasite species to the egg count explains the relatively poor and inconsistent fit of the negative binomial distribution to faecal egg counts in lambs.

The systematic position of some Ethiopian Nippostrongylinae (Nematoda, Trichostrongylina, Heligmosomoidea) from the National Collection of Animal Helminths, Onderstepoort, South Africa

The taxonomic status of some nippostrongyline nematodes deposited in the National Collection ofAnimal Helminths, Onderstepoort, is revised. Heligmonina boomkeri n. sp. is described from Aethomys chrysophilus from South Africa. The most closely related species by the body measurementsand the pattern of the caudal bursa is Heligmonina bignonensis Diouf, Bâ & Durette-Desset, 1997, a parasite of Mastomys erythroleucus from Senegal. It differs from the new species mainly in thenumber of ventral cuticular ridges at mid-body (four versus five) and the left ala in the male is shorterthan the body diameter. The systematic position of Heligmonina spira (Ortlepp, 1939) and Neoheligmonella capensis (Ortlepp, 1939) is confirmed here through their synlophe, which was not previously studied.

Impact on productivity of peri-parturient rise in fecal egg counts in Creole goats in the humid tropics

The control of gastrointestinal nematodes requires an understanding of their epidemiology so that particular parasite stages can be targeted. Dam infection during early lactation is one example of this in ruminant nematode infections. The existence of the peri-parturient relaxation in immunity and its impact on productivity were examined in a Creole goat flock from Guadeloupe, exposed to mixed natural infection (predominantly Haemonchus contortus and Trichostrongylus colubriformis). A total of 1,511 l were obtained from 909 does resulting from 463 dams and 150 sires. Fecal and blood samples were collected at kidding before anthelmintic drenching, 4 and 6 weeks after kidding. The traits analyzed were logarithm transformed fecal egg counts (FEC), packed cell volume (PCV), and logarithm transformed blood eosinophilia counts (EOS) for does at each sampling point and changes in these during the postpartum period. With the exception of the PCV values measured at kidding, lactating does had significantly higher FEC and lower PCV than control dry does at every sampling point. Geometric means of FEC in lactating does were 819 +/- 174, 677 +/- 146 and, 699 +/- 160 eggs per gram (EPG) at kidding, 4 and 6 weeks after kidding respectively. Geometric means of FEC in dry does were 187 +/- 57, 89 +/- 28, 133 +/- 43 at these time points, respectively. EOS differences were not consistent between groups and probably not specific enough for variations in Creole goats' peri-parturient rise to be discussed. As does aged, their egg output decreased and primiparous does always had greater egg output than multiparous ones. Overall, does' FEC at 4 weeks after kidding decreased by 1.3% each year. The higher the litter size, the higher the FEC at kidding and inverse applied for PCV measurements. Does that stopped lactating had significantly lower FEC and higher PCV values than lactating does with low milk yields. Higher infection rates during early lactation in Creole goats were recorded in does with lower maternal ability assessed by the average daily weight gain of kids between 10 and 30 days of age. Kids from dams with higher FEC (i.e. >600 EPG higher than corresponding does) had 17% lower average daily weight gain between 30 and 70 days postpartum and were approximately 1 kg lighter at weaning than kids from dams with lower FEC. Thus, it is clear that a peri-parturient rise in FEC exists in Creole goats. By controlling the intensity of this peri-parturient rise in FEC, herd health and productivity could be substantially improved.

Effect of a low protein diet on the resistance of Churra sheep to Teladorsagia circumcincta

SUMMARY The aim of this study was to understand the influence of a low protein diet on the resistance of the Churra breed sheep to infection with Teladorsagia circumcincta. A previous experiment in our department demonstrated significant differences between resistant and susceptible sheep infected with T. circumcincta, in eggs per gram of faeces, serum pepsinogen, serum IgA and peripheral eosinophilia (unpublished). The sheep were fed with a balanced protein diet. In the current assay there were significant differences between the resistant and susceptible groups in egg output, serum pepsinogen and worm burden. The optical densities (OD) of the IgA in blood samples, nasal secretions and saliva were tested throughout the study and the differences between groups were not significant. At necropsy adult worm length, the number of eggs in utero in adult females, the number of fourth stage larvae and the OD of gastric mucus IgA did not differ between groups either. Moreover, due to diet there was a loss of weight in both groups but this was not significant. Our results support the view that low protein diets could influence immune function and as a result resistant genotypes do not show any superiority in comparison with susceptible ones.

Genetic resistance to Teladorsagia circumcincta: IgA and parameters at slaughter in Churra sheep

SUMMARY Previous experiments have shown that genetic resistance to infection by Teladorsagia circumcincta in sheep can be measured by the level of IgA in gastric mucus, jointly with other parameters. The aim of this study has been to observe the influence of IgA on adult worms. The experiment was carried out with Churra sheep experimentally infected with T. circumcincta. At slaughter, gastric content, gastric mucus, blood samples and faeces were recovered to determine the number of eggs in utero, length of adult females, worm burden, number of L4, titre of serum pepsinogen, peripheral eosinophilia and eggs per gram (epg). IgA activity in gastric mucus, serum, nasal secretions and saliva were tested against somatic antigen from fourth-stage larvae (L4), somatic antigen from the adult stage and excretory-secretory (E/S) antigen from the adult stage. The results showed a significant correlation between serum IgA and gastric mucus (P<0.01) as well as in nasal secretions (P<0.01). We found negative correlations between IgA activity in gastric mucus with the eggs in utero and with adult female length. Furthermore there were also strong relationships between the peripheral eosinophilia with serum (P<0.01) and gastric mucus IgA activity (P<0.01). Moreover serum pepsinogen and the number of L4 at slaughter were related (P<0.01).

Production of eosinophil chemoattractant activity by ovine gastrointestinal nematodes

Eosinophilia is a well documented feature of helminth infections but the precise nature of the interaction between parasite and eosinophil remains an enigma. This paper describes experiments demonstrating that ruminant gastrointestinal trichostrongyles produce potent chemoattractant activity for ovine bone marrow-derived eosinophils in vitro. This activity was initially identified as a constituent of whole worm extracts of third and fourth larval (L3, L4), and adult stages of Teladorsagia circumcincta, and adult Haemonchus contortus. Similar activity was detected in excretory/secretory (E/S) material derived from live T. circumcincta L3. Subsequently, by adapting the assay technique to incorporate live worms directly into the system, it was shown that L3 of both T. circumcincta and H. contortus produced eosinophil chemoattractant activity. In contrast, neither whole worm extracts, or E/S preparations from mixed stages of the free-living nematode Caenorhabditis elegans contained eosinophil chemoattractant activity, and there was no evidence of chemoattractant production by live C. elegans. The results described are challenging to the traditional dogma that eosinophils are host-protective effector cells, and raise the intriguing possibility that ovine nematodes actively encourage recruitment of eosinophils. Local eosinophil-mediated mucosal damage, comparable to that seen in the asthmatic lung, may then provide a permissive local microenvironment for the parasite. Moreover, if they prove important for pathogenicity, nematode chemoattractants could offer future potential as novel therapeutic targets.

Very low helminth infection in sheep grazed on pastures fertilised by sewage sludge or cattle slurry

Helminth infection acquired by lambs grazing on pastures fertilised either by urban sewage sludge or cattle slurry were studied in temperate Central Western France. The aim was to assess the risk of larval cestodoses in lambs after sewage application and of digestive tract nematode infection following the slurry application. Twenty-six sheep were allocated on two paddocks of 0.7 ha, one fertilised with sludge and the other with cattle slurry. The delay between application and actual grazing was 6 weeks; grazing on these paddocks extended from mid July to beginning of November 2002. The herbage biomass was slightly increased in the sludge paddock but it did not result in an increase of lamb live weight, compared with the slurry paddock. The lambs did not acquire cysticercosis or any other larval cestodoses in the sewage sludge group and only very limited infections with Cooperia spp. and Nematodirus spp. were observed in the slurry group. It was concluded that in our conditions the helminth risk was extremely low and was not a cause of restriction of the use of these biowastes.

A new species of Vexillata (Nematoda: Trichostrongylina: Ornithostrongylidae) parasite of Heteromys desmarestianus (Rodentia: Heteromyidae) from Costa Rica

In July 1999, 2 heteromyid rodents Heteromys desmarestianus Gray, 1868, were collected from the Area de Conservación Guanacaste, Costa Rica, and examined for parasites. Individuals of a new species of Vexillata (Travassos, 1937) Durette-Desset, 1970, were found from the intestine of hosts. Vexillata brooksi n. sp. differs from all other congeners by the presence of spicules divided at the tip instead of simple spicules. The new species closely resembles Vexillata legallae Denke, 1977, and Vexillata convoluta (Caballero and Cerecero, 1943); however, it can be distinguished from both species by possessing a smaller number of cuticular ridges at the posterior part of the body in males (9 vs. 11 and 12, respectively) and by the absence of a carene at this level.