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PubMed1993

Biological control of nematode parasites in cattle with nematode-trapping fungi: a survey of Danish studies.

In Denmark two series of experiments have been performed to study the interactions between larvae of bovine gastrointestinal nematode parasites and nematode-trapping fungi. For practical reasons we were interested in the possibility of depositing nematode-trapping fungi in cattle faeces after passage through the gastrointestinal tract. In the first series, laboratory tests with the fungus Arthrobotrys oligospora showed that motile free-living larvae of a wide range of animal-parasitic nematodes and some soil-living nematodes effectively induce the formation of traps. Larvae of all parasitic nematodes are rapidly captured in these traps. The induction of nets was influenced by temperature, number of larvae, atmosphere, light, and media composition. Captured first- and second-stage larvae were quickly penetrated and killed while third stage larvae were killed slowly, perhaps because they are partially protected by an outer dead sheath. Laboratory and field studies showed that when A. oligospora material was directly mixed into dung a significant reduction in the number of infective parasite larvae in the dung and surrounding herbage occurs. This reduction was also reflected in the acquired worm burden of calves grazing on fungal treated pasture. However, the A. oligospora strain studied in the above mentioned experiments did not survive passage through the alimentary tract of cattle. This prompted us to start a second series of experiments to isolate fungi that could survive gut passage of cattle. Different soil and compost samples were screened by an in vitro stress selection technique. This simulated certain important stress factors which occur during passage through the alimentary tract of ruminants. Rumen exposure was found to be a major limiting factor, but some Arthrobotrys and Duddingtonia strains survived submersion in rumen fluid. In a subsequent in vivo experiment, some of these survivors were fed to calves, and it was hereby demonstrated that isolates of both genera, i.e. Arthrobotrys and Duddingtonia, were able to survive passage through calves and significantly reduce the number of developing preparasitic larvae in dung of fungal treated calves. In a controlled field experiment, isolates of Duddingtonia reduced the level of infective third-stage larvae in herbage by 74-85%.

Animals↗
PubMed1988

Control of gastrointestinal parasitism with an oxfendazole pulse-release anthelmintic device.

The efficacy of a pulse-release oxfendazole bolus (OPRB) against gastrointestinal nematodes was evaluated under field conditions and compared with a sustained release morantel bolus (MSRB). Three groups of 10 calves were grazed from May to September on adjacent, similarly contaminated 3-acre paddocks. One group was dosed at turnout with the OPRB, the second group with the MSRB and the third group left as nontreated controls. Pasture larval counts peaked at greater than 60,000 larvae/kg dry weight of herbage in September on the control paddock, associated with a mean egg count of 1040 eggs/g faeces and clinical symptoms. A low rise in larval counts occurred on the MSRB plot, and also low helminth egg counts. On the OPRB plot, pasture larvae and faecal egg counts were recorded only intermittently; the September egg counts were only 3.5% of those of the controls; serum pepsinogen data showed a similar picture. At the end of the experiment, the OPRB calves had a mean weight advantage of 40 kg over the controls, and 12 kg over the MSRB group. Feed intakes were highest in the OPRB group in July and September.

Animals↗
PubMed2000

Efficacy of copper oxide needles for the control of nematode parasites in dairy goats.

The spread of benzimidazole-resistant nematodes in dairy goat farms is of a great concern as probably more than 70% of the flocks are involved. As there are very few other anthelmintic options during the lactating period, we have evaluated the efficacy of copper oxide needles (CON, Copinox, Bayer, UK) in both experimental and natural infections in goats. The curative effect of CON (2-4 g) on existing worm burdens was assessed in goats experimentally infected with Teladorsagia circumcincta, Haemonchus contortus and Trichostrongyus colubriformis, compared to controls. The preventive effect of CON (4 g) on worm establishment was monitored for 2 months in animals experimentally infected with H. contortus and for 3 months in naturally infected animals on a farm exhibiting predominant infections with T. circumcincta and Oesophagostomum venulosum. In both experimental and natural conditions, the efficacy of CON was nil against Teladorsagia, Trichostrongylus and Oesophagostomum infections. In contrast, the efficacy of CON against Haemonchus was clearly established in reducing the worm burden (75%) as well as in lowering the egg output (37-95%) in relation to the establishment of new infections over several weeks. Copper oxide needles may represent an alternative to conventional anthelmintics in the control of Haemonchus infection in some goat farms.

Administration, Oral↗
PubMed1980

Control of internal parasites in dairy replacement heifers by two treatments in the spring.

Eleven dairy replacement heifers (mean body weight, 262.0 kg) were given two treatments with levamisole in the spring to reduce worm egg output and consequent pasture contamination with infective nematode larvae during the summer/autumn grazing season. The treatments were given 3 weeks and 76 weeks after the heifers were moved from confinement to permanent pastures in may 1979, at which time they were 5 to 12 months old. Treated heifers gained significantly (P < 0.01) more weight than a group of 11 control heifers (mean body weight, 262.4 kg) and outweighed them by mean values of 9.2, 19.7, 31.0, and 39.5 kg at the end of July, August, September, and October, respectively. Control heifers had highest egg counts (47-51 eggs/g) from July to September, but there was a 2-month delay before treated heifers attained peak concentrations (42 eggs/g). This delay occurred at a critical time of the year (July, August), when environmental conditions were favorable for the rapid development of eggs to infective larvae. When the egg count for treated heifers peaked at the end of September, environmental conditions were no longer favorable for optimal development of free-living stages.

Animals↗
PubMed2006

Chemokine CC receptor 2 is important for acute control of cardiac parasitism but does not contribute to cardiac inflammation after infection with Trypanosoma cruzi.

The CC chemokine ligand 2 (CCL2) and CC chemokine receptor 2 (CCR2) are expressed in the heart after infection with Trypanosoma cruzi, suggesting that they play an important role in host defense. Infection of CCR2-deficient (CCR2(-/-)) mice with T. cruzi resulted in increased cardiac parasitism, yet the severity of cardiac inflammation was not affected. In addition, expression of interferon- gamma and inducible NO synthase in the heart, which are associated with effective killing of trypomastigotes, was not affected in CCR2(-/-) mice. These observations reveal that CCR2 signaling plays a distinct role that is separate from that of influencing either chemotaxis or previously defined anti-trypomastigote mechanisms for the control of T. cruzi's replication in the heart.

Animals↗
PubMed2006

The reflection of control programs of parasitic diseases upon gastrointestinal helminthiasis in Dakahlia Governorate, Egypt.

The study area included Mansoura city as an urban area and Gogar village as a rural area. One thousand individuals were randomly selected from each area. Different methods of stool examination, perianal swab and urine examination of all participants revealed that the incidence in Mansoura city was in a descending order Heterophyes heterophyes 6.4%; Enterobius vermicularis 3.9%; Hymenienolepis nana 2.2%; Schistosoma mansoni 0.5%; Trichostrongylus colubriftormis; Strongyloides stercoralis and Fasciola sp. were recorded as 0.2% of each. Taenia saginata, Ascaris lumbricoides and Trichocephalus trichiuris were recorded as 0.1% of each. Neither Ancylostoma duodenale nor Hymenolepis dimninuta was recorded. In Gogar, the parasitic infection was H. hetephyes 4.5%; E. vermicularis 4.1%: H. nana 3.3%; S. mansoni 1.6%; T. colubriformis 0.9%; S. stercoralis 0.5%. Fasciola sp. 0.4%; T. saginata, A. lumbricoides, H. diminuta, A. duodenale and T. trichiuris were recorded as 0.1% of each. None S. haematobiumn was detected in both areas. So, the infection rates of H. heterophyes, E. vermicularis, H. nana S. mansoni, Fasciola sp., T. colubriformis and S. stercoralis were relatively high the rural than in urban area. This was not surprising since the socioeconomic, hygienic conditions and medical services were relative high in the city than in the village. No doubt, the identifications of parasitosis pave the way for feasible treatment and control measures.

Adult↗
PubMed1984

Implications of parasite-nutrition interactions from a world perspective.

Parasitic intestinal infections are among the most common in Africa, Asia, and Latin America. Although the mortality and morbidity caused by intestinal parasitic infections are relatively low, the absolute number of deaths and cases of disease is rather high in relation to other bacterial and viral infections. Scientific evidence for a causal relationship between intestinal parasitic infections and malnutrition is only fragmentary. The overdispersed frequency distribution of helminth parasites in the human population and the stability of giardiasis in some individuals may help only to define the potential target groups for immediate medical intervention, i.e., those patients heavily parasitized and/or severely malnourished. Long-term preventive intervention should include prenatal control of malnutrition, breast feeding and proper weaning food practices, oral rehydration for acute diarrhea, and immunization and possibly control of parasitic infections. Solid arguments in favor of the latter are expected to emerge from the field studies on intestinal parasitic infections and nutrition designed in 1981 by the World Health Organization and the United Nations Children's Emergency Fund. The results of these studies that will be carried out in several countries should serve as a guide for future parasite control projects and nutritional policies, including supplementary feeding programs.

Intestines↗
PubMed2006

NK cell responses to Plasmodium infection and control of intrahepatic parasite development.

Various components of innate and adaptive immunity contribute to host defenses against Plasmodium infection. We investigated the contribution of NK cells to the immune response to primary infection with Plasmodium yoelii sporozoites in C57BL/6 mice. We found that hepatic and splenic NK cells were activated during infection and displayed different phenotypic and functional properties. The number of hepatic NK cells increased whereas the number of splenic NK cells decreased. Expression of the Ly49 repertoire was modified in the spleen but not in the liver. Splenic and hepatic NK cells have a different inflammatory cytokines profile production. In addition, liver NK cells were cytotoxic to YAC-1 cells and P. yoelii liver stages in vitro but not to erythrocytic stages. No such activity was observed with splenic NK cells from infected mice. These in vitro results were confirmed by the in vivo observation that Rag2(-/-) mice were more resistant to sporozoite infection than Rag2(-/-) gamma c(-/-) mice, whereas survival rates were similar for the two strains following blood-stage infection. Thus, NK cells are involved in early immune mechanisms controlling Plasmodium infection, mostly at the pre-erythrocytic stage.

Animals↗
PubMed2001

Murine ileitis after intracellular parasite infection is controlled by TGF-beta-producing intraepithelial lymphocytes.

BACKGROUND & AIMS: Acute inflammatory ileitis occurs in susceptible (C57BL/6) mice after oral infection with Toxoplasma gondii. Overproduction of interferon (IFN)-gamma and synthesis of nitric oxide mediate the inflammation. We evaluated the role of transforming growth factor (TGF)-beta produced by intraepithelial lymphocytes (IELs) in this process. METHODS: We analyzed the histologic and immunologic consequences of adoptive transfer of antigen-primed IELs into susceptible mice treated with anti-TGF-beta before oral challenge with T. gondii cysts. An in vitro coculture of enterocytes and IELs assessed the production of chemokines and cytokines in the presence of anti-TGF-beta. RESULTS: Antigen-primed IELs prevent acute ileitis in susceptible mice that is reversed with anti-TGF-beta. Resistant mice (CBA/J) develop ileitis after treatment with anti-TGF-beta. Antigen-primed IELs can induce systemic immunosuppression as measured by depressed IFN-gamma production. In vitro, primed IELs reduce the production of inflammatory chemokines by infected enterocytes and IFN-gamma by splenocytes. CONCLUSIONS: Regulation of the ileal inflammatory process resulting from T. gondii is dependent on TGF-beta-producing IELs. The IELs are an essential component in gut homeostasis after oral infection with this parasite.

Animals↗
PubMed1999

Biological control of nematode parasites of livestock in Fiji: screening of fresh dung of small ruminants for the presence of nematophagous fungi.

Approximately 2500 faecal samples were collected per rectum from sheep and goats from 26 farms located on four of the Fijian islands where most of the small ruminants in this country are raised. The purpose was to screen these samples to isolate nematode-trapping fungi that had been acquired by these animals during the course of their feeding and which had remained viable following passage through their gastrointestinal tract. From these samples, 23 examples of nematophagous fungi were noted in the initial appraisal, from which 12 pure isolates (all of the genus Arthrobotrys) were made. A number factors emerged from this work which may have restricted the opportunities in which nematophagous fungi were detected, or isolated.

Animals↗
PubMed1989

Immunologic control of a parasitic arthropod. Identification of a protective antigen from Boophilus microplus.

Cattle can be vaccinated against the tick Boophilus microplus by inducing an immunologic reaction against Ag in the tick gut. The uptake of antibody during feeding leads to severe damage to the parasite. One of the responsible tick gut Ag has now been purified and characterized: the Bm86 Ag. It is a membrane-bound glycoprotein present in very low abundance in extracts of partially engorged adult female ticks. It has an apparent m.w. of 89,000, an isoelectric point of 5.1 to 5.6 and an affinity for wheat germ lectin. Microgram amounts of this Ag are able to induce effective protection in cattle against the parasite, as shown by the decreased survival of ticks on vaccinated cattle and a reduction in engorgement weights and egg laying capacity of the survivors. Antisera to the Ag react with the surface of digest cells in the tick gut. As a result of the reaction with antibody, the endocytotic activity of these cells, which is a critical step in bloodmeal digestion in this tick, is strongly and rapidly inhibited. A number of peptides from this Ag, produced by digestion of the reduced and alkylated protein with endoproteinase lys-C, have been sequenced. One peptide has significant amino acid sequence homology with the epidermal growth factor precursor and a second peptide has homology with a putative protective antigen from Plasmodium falciparum.

Amino Acid Sequence↗
PubMed1990

Acquired resistance in goats following a single primary Schistosoma bovis infection.

The course of Schistosoma bovis infection was monitored in West African Dwarf Goats over a 34-week period following primary, experimental exposure (3000 cercariae/animal) and over a 17-week period following challenge exposure (2500 cercariae/animal) of goats harbouring 17-week old primary infection. For comparison, groups of challenge control and parasite-free control animals were monitored. Maximal egg excretion observed from week 8 to 12 following primary infection was accompanied by reduced weight gain, marked anaemia, hypoalbuminaemia and eosinophilia. These changes gradually diminished in parallel with decreasing egg excretion from week 14 onwards. Challenge infection induced neither additional egg excretion nor adverse effects in primary-infected animals. This was in contrast to challenge control animals which revealed the typical course of experimental schistosome infection including a peak of egg excretion, weight gain affection, and associated clinico-pathological changes. It was concluded that goats are capable of mounting an effective regulatory response to single primary S. bovis infection as well as to superimposed homologous challenge infection. Further elucidation of the regulatory response to S. bovis infection in goats are needed in order to determine its possible immunological background and epidemiological impact.

Animals↗