Nematode Infections In Ruminants Research Articles

Invitro and in vivo anthelmintic efficacy of peppermint (Mentha x piperita L.) essential oil against gastrointestinal nematodes of sheep.

Nowadays, the exclusive use of commercial anthelmintics for the treatment of gastrointestinal nematode infections in ruminants is less sustainable due to anthelmintic resistance, as well as the problem of drug residues in animal products and the environment. Therefore, an integrated therapeutic approach is needed, including the search for alternatives to synthetic anthelmintic drugs. The aim of this study was to evaluate the possibility of using the essential oil of peppermint (Mentha x piperita L.) in the control of gastrointestinal nematodes in sheep. For this purpose, the in vitro and in vivo anthelmintic efficacy of this oil and the toxic effects on the hosts were examined. In the in vitro egg hatch test, ovicidal activity varied from 21.0-90.3% depending on the concentration of essential oil used (0.0125, 0.025, 0.049, 0.195, 0.781, 3.125, 12.5, and 50 mg/mL). To some extent, anthelmintic efficacy was confirmed in the in vivo fecal egg count reduction test at a mean dose of 150 mg/kg, with an average reduction of nematode eggs of 26.9 and 46.0% at Days 7 and 14 after treatment, respectively. Furthermore, no toxic effects of applied oil were observed on sheep behavior, kidney, or liver function. The main compounds identified by gas chromatography-mass spectrometry analyzes were menthol (32.6%), menthone (22.0%), menthyl-acetate (10.0%), and isomenthone (9.39%). Due to their complex chemical compositions, numerous bioactive ingredients, and natural origin, herbal formulations represent a potentially valuable alternative for the control of gastrointestinal nematodes in sheep. In this context, the results of the present study showed that peppermint essential oil is one of the promising candidates. Further studies should be performed to collect more data on the safety profile of M. piperita EO in treated animals to find the most appropriate formulation for use in field conditions and to test it against resistant gastrointestinal nematode populations.

Effects of Raising or Lowering Molybdenum Status on Outcome of Acute Infection with Nippostrongylus brasiliensis in Mature Rats

Molybdate (Mo+) supplements can suppress or enhance nematode infections in ruminants, depending on exposure level, but there have been no investigations in non-ruminants. Three groups of 16 mature rats were each fed a commercial diet and given Mo+ (10mg Mo/l), tungstate (a molybdenum [Mo] antagonist) (MoO4, 350mgW/l) or no supplement (C) via drinking water for 40 days before acute infection with 3,600 Nippostrongylus brasiliensis larvae. Group Mo- also received allopurinol (1g/l), a molybdenoenzyme inhibitor, from 4 days post infection (dpi). Subgroups of four rats from each group were killed at 7-14 dpi. A group of six rats was left untreated and uninfected and subgroups killed 10 or 12 dpi. Infection reduced intakes of food and water but impacts were greatest in group Mo-. Median worm counts in groups C, Mo- and Mo+ were 900, 941 and 510, respectively, at 7 dpi and 9, 40 and 0 (P=0.05) at 10 dpi. Median faecal egg counts were consistently lowest in group Mo+. Worm weight was reduced (P<0.05), worm tissue protease increased and superoxide dismutase activities increased in worm (P<0.01) and host duodenal homogenates (P<0.01) from group Mo+. In group Mo-, liver Mo concentration decreased, duodenal xanthine oxidoreductase activity (DXOR) became totally inhibited and plasma uric acid was barely detectable at 10 dpi. Plasma mast cell protease activity and duodenal malonyldialdehyde concentrations, markers of inflammation, were increased by nematode infection (P<0.001) but unaffected by water treatments. Liver Mo, liver copper (Cu) and plasma Cu concentrations were increased in group Mo+ and plasma Cu concentration was increased in group Mo- suggesting systemic exposure to partially thiolated MoO4 and WO4. Supplementary MoO4 impaired larval establishment and changed parasite biochemistry without affecting the inflammatory response to infection but may have required partial thiolation to do so. Rats did not rely on DXOR activity to expel N. brasiliensis.

In vitro anthelmintic activities of three ethnomedicinal plant extracts against Haemonchus contortus

Aim of study: To investigate the in vitro anthelmintic efficacies of three plants, Annona senegalensis (AS), Cochlospermum planchonii (CP), and Sarcocephalus latifolius (SL), used by livestock farmers in Northern Nigeria, to treat gastrointestinal nematode infections in ruminants. Area of study: Makurdi, Benue State, Nigeria. Materials and methods: The plants were selected through a structured questionnaire administered to livestock farmers in Northern Nigeria. Aqueous and acetone leaf (AS and SL) and root (CP) extracts of these plants were investigated for their anthelmintic activity against Haemonchus contortus using the egg hatch inhibition assay at concentration levels of 0.3125 to 10 mg/mL in 2.5% dimethyl sulfoxide. Main results: A probit log-dose response analysis showed that acetone extract of CP achieved 100% egg hatch inhibition similar to the commercial drug at all tested concentrations after 48 hours of incubation, while AS demonstrated 88.7% egg hatch inhibition. Acetone extract of SL had less than 50% egg hatch inhibition at all tested concentrations. On the other hand, the aqueous extract of CP and SL both exhibited 100% inhibition at 5 and 10 mg/mL of the tested concentrations, while AS had less than 50% egg hatch inhibition at all tested concentrations. Research highlights: This study identified CP, AS, and SL as medicinal plants with rich sources of molecules that have potential value in the development of novel anthelmintic drugs.

Serum pepsinogen and gastrin concentrations in South American camelids with and without gastrointestinal nematode infection

Abstract Endoparasitosis is one of the major health problems in South American camelids (SACs) often leading to massive damage of the gastric or intestinal mucosa. In ruminants this damage results in increased gastrin and pepsinogen concentrations in the peripheral blood. These values have been used as diagnostic parameters for subclinical gastrointestinal nematode infections in ruminants but have not been systemically studied in SACs. Serum pepsinogen and gastrin concentrations of 183 clinically healthy SACs with and without detectable parasitic egg excretion and the occurrence of occult blood in the faeces were determined. The median (1st/3rd quartile) of serum pepsinogen and gastrin were 1899.4 (1483.1/2749.4) ng/ml and 184.8 (121.8/340.5) pg/ml for alpacas; 1642.0 (1182.3/2608.7) ng/ml and 191.8 (142.2/287.6) pg/ml for llamas respectively. A sensitivity of 80.1 % and a specificity of 11.1 % for gastrin (cut off 402 pg/ml) and a sensitivity of 64.1 % and specificity of 88.9 % for pepsinogen with endoparasitosis (cut off 1996 ng/ml) were calculated. Based on our results, albeit on quite small numbers, determination of serum gastrin concentration does not seem to be a useful test for the detection of endoparasitic infection in SACs. In contrast, for pepsinogen a correlation was found between serum concentration and animals with and without endoparasitosis. Nevertheless further studies are necessary in order to investigate the diagnostic potential of pepsinogen serum concentration in relation to subclinical endoparasitosis.

Increased susceptibility to Haemonchus contortus infection by interleukin-5 modulation of eosinophil responses in sheep.

Eosinophils are prominent effector cells in immune responses against gastrointestinal nematode infections in ruminants, but their in vivo role has been hard to establish in large animals. Interleukin-5 is a key cytokine in the induction and stimulation of anti-parasitic eosinophil responses. This study attempted to modulate the eosinophil response in sheep through vaccination with recombinant interleukin-5 (rIL-5) and determine the effect on subsequent Haemonchus contortus infection. Nematode-resistant Canaria Hair Breed (CHB) sheep vaccinated with rIL-5 in Quil-A adjuvant, had lower blood eosinophil counts and higher mean worm burdens than control sheep vaccinated with Quil-A adjuvant alone. In addition, adult worms in IL-5-vaccinated sheep were significantly longer with higher eggs in utero in female worms, supporting an active role of eosinophils against adult parasites in CHB sheep. These results confirm that eosinophils can play a direct role in effective control of Hcontortus infection in sheep and offer a new approach to study immune responses in ruminants.

Nematodes Resistance on Anthelmintics Group of Benzimidazole in Ruminants

One factor that inhibits the increase in ruminant productivity is nematode infection. It’s cause a decrease in feed intake, weight gain, milk production, disease, death, and expensive medical expenses The control of gastrointestinal nematode infections in livestock, over the past decades is primarily based on the preventive or curative use of chemotherapeutics and generally uses broad-spectrum anthelmintic such as benzimidazole, probenzimidazole, imidazothiazole, macrolide and ivermectin. The widespread use of several antelmintic groups now causes an increase in the incidence of gastrointestinal nematodes resistance against anthelmintics. Anthelmintics derived from various types of plants are expected to replace the benzimidazole so that it can reduce the level of resistance of the gastrointestinal nematodes in ruminants. However, for the future there is still a lot of research needed to further improve the ability of natural medicinal drugs to cope with gastrointestinal nematode infections in ruminants. Keywords : benzimidazole, nematode,resistance, ruminants

Risk factors associated with occurrence of anthelmintic resistance in sheep of resource-poor farmers in Limpopo province, South Africa.

Anthelmintic treatment is the most common way of controlling nematode infections in ruminants even though several countries have reported anthelmintic resistance (AR), resulting in limitation for sustainable small ruminant production. The aim of the present study was to evaluate the knowledge of resource-poor sheep farmers in Limpopo province of South Africa on the use of anthelmintics. A questionnaire regarding helminthosis control practices was administered to small ruminant farmers in five districts of Limpopo province namely Capricorn, Sekhukhune, Waterberg, Vhembe, and Mopani. A total of 77 resource-poor farmers were interviewed between June and August of 2017 using a structured questionnaire with a combination of qualitative and quantitative open-ended questions. The interviewed farmers were divided into three groups based on their farming experience (< 5; 6-10, and ˃10years of farming experience). Limited farming experience was shown as one of the risks, as farmers that owned sheep for less than 10years could not identify the symptoms of gastrointestinal parasites infection and did not know how nematodes are transmitted to animals. However, no significant difference (p < 0.05) was found to exist between the three groups of farmers in terms of clinical signs identification and correct application of anthelmintics. About 43% of the respondents were unaware of gastrointestinal nematodes (GI) that infect sheep, could not identify the clinical symptoms of gastrointestinal nematodes infection, and only 34% knew how animals become infected. Although 67.5% of farmers mentioned that they never dose their sheep, 32.5% use anthelmintics at varying times in a year. None of the farmers weighed their sheep before dosing them instead visual appraisal of individual weight was the most common means of estimating the anthelmintic dose. The above information is an indication of risks associated with possible occurrence of anthelmintic resistance in the study areas. There is therefore, a need to give training to resource-poor farmers of small stock on proper application of anthelmintic treatment and to educate them on how to prevent development of AR. Future studies on AR should also be conducted in the province in flocks with high-treatment frequencies to establish the occurrence of AR using both in vivo and in vitro methods. The most common risk factor associated with the occurrence of AR in all the five districts of Limpopo province was found to be the use of anthelmintics without weighing the animals to determine the correct dosage.

Immunogenomics of gastrointestinal nematode infection in ruminants - breeding for resistance to produce food sustainably and safely.

Gastrointestinal nematode (GIN) infection of ruminants represents a major health and welfare challenge for livestock producers worldwide. The emergence of anthelmintic resistance in important GIN species and the associated animal welfare concerns have stimulated interest in the development of alternative and more sustainable strategies aimed at the effective management of the impact of GINs. These integrative strategies include selective breeding using genetic/genomic tools, grazing management, biological control, nutritional supplementation, vaccination and targeted selective treatment. In this review, the logic of selecting for "resistance" to GIN infection as opposed to "resilience" or "tolerance" is discussed. This is followed by a review of the potential application of immunogenomics to genetic selection for animals that have the capacity to withstand the impact of GIN infection. Advances in relevant genomic technologies are highlighted together with how these tools can be advanced to support the integration of immunogenomic information into ruminant breeding programmes.

Advances in the diagnosis of the gastrointestinal nematode infections in ruminants

A quantificação de ovos de nematoides em amostras de fezes e a identificação morfológica das larvas de terceiro estágio a partir de culturas de fezes têm sido amplamente utilizadas, com resultados satisfatórios para o diagnóstico das infecções por nematoides gastrintestinais em ruminantes. Com o intuito de melhorar a sensibilidade na detecção dos ovos, outras técnicas, tais como Flotac e Miniflotac, têm sido empregadas. Resultados obtidos em diferentes estudos indicam que a contagem de ovos nas fezes é uma medida confiável e representativa da magnitude da carga parasitária. No entanto, o estado imunológico dos animais deve ser considerado na interpretação dos resultados coproparasitológicos. As técnicas moleculares também têm sido úteis no diagnóstico das enfermidades parasitárias. Os maiores avanços no diagnóstico têm sido propiciados pelo desenvolvimento de plataformas robóticas, que separam os ovos das fezes com pouca manipulação, propiciando a obtenção de DNA de ovos de boa qualidade, o que resulta em uma amplificação que possibilita indicar o grau da infecção pelas diferentes espécies de parasitas em infecções mistas. O método ideal deve ser preciso, rápido e de fácil execução por não-especialistas. Com o avanço da robótica, bioinformática e biologia molecular, espera-se que equipamentos com tais características se tornem disponíveis e acessíveis para serem utilizados na rotina laboratorial para o diagnóstico de nematoides gastrintestinais de ruminantes.

Oesophagostomum and Other Strongylid Nematode Infections in Ruminants and Pigs in the Upper East Region of Ghana

Oesophagostomum species are strongylid nematode parasites of monkeys, sheep, goats, pigs, cattle, camels and antelopes. Human infections were considered zoonotic. Studies in the northeastern parts of Ghana suggested that the human infections might be common but focally distributed. Factors determining the focal distribution are not known. The relationship between the human and animal infections is also not known. It is also not known whether the animal infections are focal in distribution. In the present study, two communities known to be endemic to the human infection (Kulbia and Kologo) and two other communities known to be non-endemic to the human infection (Kalbiong and Gbeogo) in the Upper East Region (UER) of Ghana were selected. Prevalences and intensities of Oesophagostomum infection and other related strongylid nematode infections in ruminants and pigs were determined and compared. Faecal samples from cattle, sheep, goats and pigs were collected, processed by coproculture and examined under the microscope for larvae of the different strongylid nematodes. The results show no significant Original Research Article Ahiabor et al.; ARRB, 7(1): 1-22, 2015; Article no.ARRB.2015.101 2 differences in prevalence of infection between the human endemic and human non endemic communities (P = 1.00) during the rainy season and (P =.134) in the dry season. However, there were significant differences in the intensity of infection between the two types of communities only during the dry season (P = .032). Other strongylid nematodes observed were Necator sp., Strongyloides sp. and Trichostongylus sp.

The specific diagnosis of gastrointestinal nematode infections in livestock: Larval culture technique, its limitations and alternative DNA-based approaches

The specific diagnosis of gastrointestinal nematode infections in ruminants is routinely based on larval culture technique and on the morphological identification of developed third-stage larvae. However, research on the ecology and developmental requirements of different species suggests that environmental conditions (e.g., temperature and humidity) for optimal development to occur vary between the different species. Thus, employing a common culture protocol for all species will favour the development of certain species over others and can cause a biased result in particular when species proportions in a mixed infection are to be determined. Furthermore, the morphological identification of L3 larvae is complicated by a lack of distinctive, obvious features that would allow the identification of all key species.In the present paper we review in detail the potential limitations of larval culture technique and morphological identification and provide account to some modern molecular alternatives to the specific diagnosis of gastrointestinal nematode infection in ruminants.

Evaluation of In Vitro Ovicidal Activity of Ethanolic Extracts of Prosopis juliflora (Sw.) DC (Fabaceae)

Gastrointestinal nematode infections in ruminants have direct effects such as mortality, weaknesses, feeding efficiency and decreased productivity. Animal deaths due to nematode infections are common in tropical regions where control programs based solely on the use of synthetic anthelmintics are no longer sustainable due to increased prevalence of gastrointestinal nematode resistance, slow development of new anthelmintics, high costs to poor farmers and concerns regarding residue in food and the environment. Alternative methods of control are thus required. Prosopis juliflora is a fast-growing, drought-resistant tree adapted to poor and saline soils in arid and semi-arid lands of Kenya, inhabited by nomadic pastoralists. Analysis of the EHA data using t- test revealed that there was no statistically significant difference in the activities of both LEE and REE (p>0.05). However, in comparison to ALB, the difference in activity was significantly different (p<0.05). The observed in vitro anthelmintic activity was attributed to saponins and condensed tannins and to alkaloids present in the plant. Phytochemical analysis confirmed presence of tannins, saponins and alkaloids, among other phytoconstituents. These phytochemicals are known to exhibit anthelmintic activity, therefore making the plant a potential candidate for drug development against gastrointestinal nematodes.

Can efficient management of sheep gastro-intestinal nematodes be based on random treatment?

Targeted selective treatment has been proposed as a method to reduce gastro-intestinal nematode infections in ruminants and lower the selective pressure that leads to anthelmintic resistance. Since nematodes are highly aggregated within their host population, treating only the most heavily infected hosts offers an efficient and sustainable strategy to reduce infection within the flock and slow the spread of anthelmintic resistance. Although effective methods to correctly identify such hosts are available, their feasibility is often limited in the field conditions. Instead, treating part of the flock at random may prove to be a useful and practical alternative. This study examined whether such random treatment could be relevant in controlling nematode infections and delaying the selection of anthelmintic resistance compared to targeted selective treatment. Firstly, an individual based model was used to evaluate the sustainability of random treatment according to several parasitic distributions in the host population (negative binomial, uniform and normal distributions). Anthelmintic resistance was modelled based on benzimidazoles, as a monogenic trait. Anthelmintic treatment was done twice a year, week 23 and 41, corresponding to beginning of June and of October. The model was run over a five-year period corresponding to the minimum delay for anthelmintic resistance to be observed following its initial use. The model outputs show an increase in the proportion of treated hosts led to an increase in the frequency of the resistance allele for both treatment regimes. Random treatment was shown to be slightly less efficient than targeted selective treatment in controlling for the infection intensity regardless of the percentage of hosts treated. Random treatment was however more efficient than targeted selective treatment in counter-selecting for anthelmintic resistance in both the aggregated and uniformly distributed models. Secondly, a one grazing season experiment was conducted to compare a random treatment flock (20% of flock was treated at random monthly) against a mass treatment flock (the whole flock was treated monthly). Both treatment regimes produced similar pasture infectivity, similar mean infection intensity and similar final host live weight. This is the first time random treatment of a subset of hosts has been demonstrated to be a sustainable alternative to mass treatment.

Should we aim for genetic improvement in host resistance or tolerance to infectious pathogens?

Should we aim for genetic improvement in host resistance or tolerance to infectious pathogens?

Worm control practice against gastro-intestinal parasites in Norwegian sheep and goat flocks.

BackgroundAnthelmintic treatment is the most common way of controlling nematode infections in ruminants. However, several countries have reported anthelmintic resistance (AR), representing a limitation for sustainable small ruminant production. The knowledge regarding worm control management represents a baseline to develop a guideline for preventing AR. The aim of the present study was therefore to improve our knowledge about the worm control practices in small ruminant flocks in Norway.MethodsA questionnaire survey regarding worm control practices was performed in small ruminant flocks in Norway. Flocks were selected from the three main areas of small ruminant farming, i.e. the coastal, inland and northern areas. A total of 825 questionnaires, comprising 587 sheep flocks (return rate of 51.3%) and 238 goat flocks (52.6%) were included.ResultsThe results indicated that visual appraisal of individual weight was the most common means of estimating the anthelmintic dose used in sheep (78.6%) and goat (85.1%) flocks. The mean yearly drenching rate in lambs and ewes were 2.5 ± 1.7 and 1.9 ± 1.1, respectively, whereas it was 1.0 (once a year) in goats. However, these figures were higher in sheep in the coastal area with a rate of 3.4 and 2.2 in lambs and ewes, respectively. Benzimidazoles were the predominant anthelmintic class used in sheep flocks (64.9% in 2007), whereas benzimidazoles and macrocyclic lactones were both equally used in dairy goat flocks. In the period of 2005-2007, 46.3% of the sheep flocks never changed the anthelmintic class. The dose and move strategy was practiced in 33.2% of the sheep flocks.ConclusionsThe present study showed that inaccurate weight calculation gives a risk of under-dosing in over 90% of the sheep and goat flocks in Norway. Taken together with a high treatment frequency in lambs, a lack of anthelmintic class rotation and the common use of a dose-and-move strategy, a real danger for development of anthelmintic resistance (AR) seems to exist in Norwegian sheep and goat flocks. This risk seems particularly high in coastal areas where high treatment frequencies in lambs were recorded.

Infection with the gastrointestinal nematode Ostertagia ostertagi in cattle affects mucus biosynthesis in the abomasum.

The mucus layer in the gastrointestinal (GI) tract is considered to be the first line of defense to the external environment. Alteration in mucus components has been reported to occur during intestinal nematode infection in ruminants, but the role of mucus in response to abomasal parasites remains largely unclear. The aim of the current study was to analyze the effects of an Ostertagia ostertagi infection on the abomasal mucus biosynthesis in cattle. Increased gene expression of MUC1, MUC6 and MUC20 was observed, while MUC5AC did not change during infection. Qualitative changes of mucins, related to sugar composition, were also observed. AB-PAS and HID-AB stainings highlighted a decrease in neutral and an increase in acidic mucins, throughout the infection. Several genes involved in mucin core structure synthesis, branching and oligomerization, such as GCNT3, GCNT4, A4GNT and protein disulphide isomerases were found to be upregulated. Increase in mucin fucosylation was observed using the lectin UEA-I and through the evaluation of fucosyltransferases gene expression levels. Finally, transcription levels of 2 trefoil factors, TFF1 and TFF3, which are co-expressed with mucins in the GI tract, were also found to be significantly upregulated in infected animals. Although the alterations in mucus biosynthesis started early during infection, the biggest effects were found when adult worms were present on the surface of the abomasal mucosa and are likely caused by the alterations in mucosal cell populations, characterized by hyperplasia of mucus secreting cells.

Expression of three intelectins in sheep and response to a Th2 environment.

Sheep intelectin1 and sheep intelectin3 (sITLN1 and sITLN3) were cloned and sequenced. The amino acid sequences of sITLN1 and sITLN3 shared 86% and 91% homology with the previously cloned sheep intelectin2 (sITLN2), respectively. Expression of sITLN1 and sITLN3 transcript was demonstrated in abomasum, lung, colon and gastric lymph node, terminal rectum, skin, jejunum, mesenteric lymph node, ileal peyer’s patches, brain, kidney, liver, spleen, skin, ear pinna, heart and ovary in normal sheep tissues. sITLN2 transcript expression was restricted to the abomasal mucosa in normal sheep tissues. Using a non selective chicken anti-intelectin antibody, tissue intelectin protein was demonstrated in mucus neck cells in the abomasum, mucus cells in the colon, free mucus in ileum, goblet cells in the lung, small intestinal epithelium and brush border, epidermal layer of the skin and skin sebaceous glands. The expression of the three sITLN transcripts was examined in two nematode infections in sheep known to induce a Th2 response; a Teladorsagia circumcincta challenge infection model and a Dictyocaulus filaria natural infection. The three sITLN were absent in unchallenged naïve lambs and present in the abomasal mucosa of both naïve and immune lambs following T. circumcincta challenge infection. Upregulation of sITLN2 and sITLN3 was shown in sheep lung following D. filaria natural infection. Intelectins may play an important role in the mucosal response to nematode infections in ruminants.

Ultraviolet light increases mortality of nematode larvae and can explain patterns of larval availability at pasture

Despite its documented effects on the viability of living organisms, the impact of ultraviolet (UV) light on the survival of parasitic nematode larvae has received surprisingly little attention. Infective L3s of the trichostrongyloid nematodes Haemonchus contortus, Teladorsagia circumcinta and Nematodirus battus, suspended in water, were exposed to direct UV irradiation in two experiments. In the first, during 6days of constant illumination with UVA lamps at intensities simulating sunlight at ground level, the mortality rate was increased up to 100-fold compared with controls sheltered by UV-impermeable perspex. Significant differences in mortality rates were detected between the three species, with H. contortus the least sensitive. In the second experiment, larvae were exposed to natural sunlight during the temperate spring and summer, for 24-h periods on seven separate days representing a range of weather and UV doses. Mortality was again increased by UV exposure in all species, but was less in H. contortus than in T. circumcincta or N. battus. At higher daily UV doses, the mortality rate was on average 2.27 times higher in exposed larvae than in sheltered controls. Increased mortality caused by UV irradiation could help to explain patterns of abundance of infective stages at pasture, especially pronounced population declines in spring when solar radiation rises rapidly and temperature is still low. Implications for the epidemiology of gastrointestinal nematode infection in ruminants, and for trade-offs in parasite life history, are discussed.

Up-regulation of intelectin in sheep after infection with Teladorsagia circumcincta

A novel intelectin molecule designated sheep intelectin 2 (sITLN2) was detected in sheep abomasal mucosa. The full sequence shared 76–83% homology with other mammalian intelectins. Intelectins are mucus-associated proteins that have been shown to be up-regulated in gastrointestinal nematode infections in rodents and in human asthma. Expression of sheep abomasal ITLN2 mRNA was significantly up-regulated on day 10 post-challenge of worm-free sheep with Teladorsagia circumcincta and at day 2 in previously infected, immune sheep. Increased expression of ITLN protein following challenge was confirmed by Western blot and was immunolocalised to the mucous neck cells of the abomasal mucosa. Infection with T. circumcincta was also associated with increased levels of abomasal transcripts encoding sheep mast cell protease-1, ovine galectin-14 and IL4, which collectively suggested a Th2 type response. Intelectin may play an important role in the mucosal response to gastrointestinal nematode infections in ruminants.

Value of present diagnostic methods for gastrointestinal nematode infections in ruminants

In this paper the different options for the diagnosis of gastrointestinal nematode infections are discussed. Diagnostic tests have a role in confirming the clinical diagnosis of parasitic gastroenteritis, but are more important for herd health monitoring of nematode infections, in particular for cattle. Therefore, emphasis is placed on discussing the available diagnostic parameters on their usefulness for that purpose. For clinical diagnosis the clinical signs, combined with the history of the animals is usually sufficient and a laboratory confirmation is not required. Faecal egg counts are, with two exceptions, not suitable for confirmation of the clinical diagnosis, because correlation between faecal egg counts and infection levels is usually low. These exceptions are the diagnosis of haemonchosis in small ruminants and the detection of anthelmintic resistance. This also limits the value of DNA-based tests of faecal material; even quantitative tests of nematode species specific DNA will have little value for diagnosis and monitoring. Pasture larval counts and worm counts are useful parameters for basic epidemiological studies on nematode infections. However, they are too laborious to be used for either routine diagnosis or monitoring. Blood parameters, such as gastrin and pepsinogen and serology are valuable tools for diagnosis. Pepsinogen and ELISAs based on recombinant proteins show most promise as parameters for herd health monitoring. However, extensive epidemiological studies are still needed before these parameters can be implemented in routine herd health monitoring schemes for parasitic gastroenteritis.