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At least 289 records · Page 16Linked to original sources
PubMed2004

Infection of C57BL/10ScCr and C57BL/10ScNCr mice with Leishmania major reveals a role for Toll-like receptor 4 in the control of parasite replication.

The innate immune system is essential for host defense; it senses the presence of potentially pathogenic-invading microorganisms, and the contribution of Toll-like receptors (TLRs) to this response is increasingly recognized. In the present study, we investigated the contribution of TLR4 to the course of cutaneous leishmaniasis in vivo. We used C57BL/10ScNCr (TLR4(0/0)) and C57BL/10ScCr [TLR4/interleukin-12 (IL-12)Rbeta2(0/0)] mice and compared the course of Leishmania major infection, parasite load, cell recruitment, and cytokine profile with those of wild-type C57BL/10ScSn mice. Our results confirm the importance of IL-12 receptor-mediated signaling in resistance to L. major infections. Importantly, we show that the lack of TLR4 results in an increased permissiveness for parasite growth during the innate and adaptive phase of the immune response and in delayed healing of the cutaneous lesions. The use of the tlr4 transgenic mouse strain TCr5 demonstrated unequivocally that TLR4 contributes to the efficient control of Leishmania growth in vivo.

Animals↗
PubMed1981

Prevalence of Strongylus vulgaris and Parascaris equorum in Kentucky thoroughbreds at necropsy.

At necropsy of 49 Thoroughbreds from farms with generally good parasite control programs in central Kentucky, examination was specifically made for presence of Strongylus vulgaris in all of the horses and of Parascaris equorum in 21 of them. None of the deaths of the horses was caused by infections of internal parasites. Visceral arteries were examined for specimens of S vulgaris and lesions related to migrating stages of this parasite. Contents of the small intestines were examined for P equorum. Specimens of S vulgaris were recovered from 19 (39%) horses, and arterial lesions were observed in 24 (49%) of them. Parascaris equorum was found in 9 (43%) horses. Both parasites were found to persist in generally low numbers on farms in spite of their parasite control programs applied in recent years.

Animals↗
PubMed2005

Doramectin concentration profiles in the gastrointestinal tract of topically-treated calves: Influence of animal licking restriction.

Endectocide compounds are extensively used for broad-spectrum parasite control and their topical administration to cattle is widespread in clinical practice. Pour-on formulations of moxidectin, ivermectin, eprinomectin and doramectin (DRM) are marketed internationally for use in cattle. However, variability in antiparasitic efficacy and pharmacokinetic profiles has been observed. Although the tissue distribution pattern for different endectocide molecules given subcutaneously to cattle has been described, only limited information on drug concentration profiles in tissues of parasite location after topical treatment is available. Understanding the plasma and target tissue kinetics for topically-administered endectocide compounds is relevant to optimise their therapeutic potential. The current work was designed to measure the plasma and gastrointestinal (GI) concentration profiles of DRM following its pour-on administration to calves. The influence of natural licking behaviour of cattle on DRM concentration in mucosal tissue and luminal content of different GI sections was evaluated. The trial was conducted in two experimental phases. In Phase I, the DRM plasma kinetics was comparatively characterised in free-licking and in 2-day licking-restricted (non-licking) calves. The pattern of distribution of topical DRM to mucosal and luminal contents from abomasum, duodenum, ileum, caecum and spiral colon was assessed in free-licking and non-licking calves restricted over 10 days post-administration (Phase II). The prevention of licking caused marked changes on the plasma and GI kinetics of DRM administered pour-on. In 2-day licking restricted calves, DRM systemic availability was significantly lower (29%) than in free licking animals during the first 9 days post-treatment. Following a 10-day long licking restriction period, DRM concentrations profiles in both mucosal tissue and luminal contents of the GI tract were markedly higher in animals allowed to lick freely. This enhancement in drug concentrations in free-licking compared to non-licking calves, was particularly pronounced in the abomasal (38-fold higher) and duodenal (six-fold higher) luminal content. As shown earlier for ivermectin, licking behaviour may facilitate the oral ingestion of topically-administered DRM in cattle. This would be consistent with the marked lower drug concentration profiles measured in the bloodstream and GI tract of the animals prevented from licking. The work reported here provides relevant information on the pattern of DRM distribution to the GI tract after pour-on treatment, and contributes to understand the variability observed in the antiparasitic persistence of topically-administered endectocides in cattle. The implications of natural licking in topical treatments are required to be seriously assessed to achieve optimal parasite control and to design parasitological and pharmacological studies within the drug approval process.

Administration, Topical↗
PubMedDate not supplied

[Control of parasitic diseases in Uzbekistan].

More than 200,000 patients with parasitic diseases (predominantly helminthisms, zoonotic cutaneous leishmaniasis) are annually notified in Uzbekistan. There are imported cases of malaria and sporadic cases of visceral leishmaniasis. The republic eradicated Filaria medinensis infection (dracunculosis) in 1931, town-type cutaneous leishmaniasis in 1950, malaria in 1960, visceral leishmaniasis in 1968, and hookworm diseases in 1974. Much experience has been accumulated in controlling zoonotic cutaneous leishmaniasis, large-scale social helminthisms: ascariasis, taeniarinchiasis, and hymenolepiasis.

Delivery of Health Care↗
PubMed1981

Control of parasitic bronchitis in calves: vaccination or treatment?

A 16-day infection of Dictyocaulus viviparus in two groups of calves was treated with levamisole and fenbendazole respectively. Five days afterwards the calves were reinfected with 4000 larvae and necropsied 21 days later. Although the lungworm burdens of the two groups of calves were reduced by about 70 per cent compared to a control group the clinical signs of dyspnoea, tachypnoea and coughing were indistinguishable from a primary infection. This was due to pulmonary emphysema, oedema and an acute epithelialising pneumonia apparently associated with the death and disintegration of lungworms in situ, the result of an incompletely developed immune response. The results are compared with those obtained with the lungworm vaccine. It was concluded that the outcome of any system of "control" which depends on drug therapy and reinfection is unpredictable and that vaccination offers the only effective method of prophylaxis.

Animals↗
PubMed2006

Gastrointestinal nematode control programs with an emphasis on cattle.

Control strategies for nematode parasites rely on knowledge of the relationships between the parasites and their hosts. Specifically, these programs are based on identifying crucial points of interaction in the environment provided by the host, including genetics and the immune response, and critical periods in the physical environment in which the eggs and larval stages must develop. When these targets are identified and the interactions understood, cost-effective sustainable programs can be developed using currently available antiparasitic compounds. Resistance to the major classes of anthelmintic compounds requires consideration of new approaches, such as immunity or genetics of the host. Additionally, the efficacy of these compounds can be expanded with combined or concomitant use. Increased study of the use of novel approaches, including fungi, elements such as copper, and plant products, has also occurred. This article explores each of these areas to allow readers to appreciate how various approaches may be developed and incorporated into an effective parasite control program.

Animals↗
PubMed1992

Induction of tumor necrosis factor alpha by Leishmania infantum in murine macrophages from different inbred mice strains.

The present study was undertaken to determine whether the viscerotropic species, Leishmania infantum, endemic in Italy, could induce tumor necrosis factor alpha (TNF alpha) in murine macrophages. Genetically susceptible (Lshs) and resistant (Lshr) mice were used in the attempt to correlate TNF alpha production with the ability to control parasite growth and replication. Resident peritoneal macrophages of C3H/HeN, DBA/2, CBA (Lshr), C57BL/10 and BALB/c (Lshs) mice were infected in vitro with promastigotes at a parasite to cell ratio of 8:1. No significant differences in the percentages of infected peritoneal cells of Lshs versus Lshr mice were observed until 72 h of in vitro culture. On the contrary, Kupffer cells from Lshr mice inhibited Leishmania replication. Peritoneal macrophages of resistant mice produced significantly higher amounts of TNF alpha as compared to susceptible mice. TNF alpha production of both resistant and susceptible mice peaked at about 5 h after the challenge with the parasite. No TNF alpha was found in supernatants of infected Kupffer cells from all the strains tested. The ability of macrophages from susceptible or resistant mice strains to produce TNF alpha after challenge with Leishmania infantum does not seem related to their capacity to control parasite replication in vitro.

Animals↗
PubMed2004

Evaluation of copper supplementation to control Haemonchus contortus infections of sheep in Sweden.

A pen study was conducted to assess the effect of providing daily copper mineral supplement, or copper wire particle (COWP) capsules, on established or incoming mixed nematode infections in young sheep. For lambs with established (6 week old) infections, COWP resulted in 97% and 56% reduction of the adult and early L4 stages of H. contortus, respectively, compared with controls (p<0.001). Additionally there was a 74% reduction in Teladorsagia circumcincta infections in the COWP lambs compared with controls (p<0.01). However, no effect was observed when COWP were given at the commencement of a larval dosing period of 6 weeks. There was no significant effect of copper mineral supplement (given at the recommended rate to prevent Cu deficiency) on either established, or developing parasite infections. In addition, a field trial was conducted on a commercial farm to assess the effects of COWP in the management of recurrent H. contortus infections, but lack of parasites during the grazing season prevented an adequate assessment from being made. These results indicate that there is little, if any, benefit from a parasite control standpoint in recommending copper therapy, specifically to control parasites in Swedish sheep flocks.

Animals↗
PubMed1987

Assessment of an oxfendazole pulsed release bolus for control of parasitic gastroenteritis in calves in a rotational grazing system.

A group of 71 Friesian bullocks, aged six to nine months, vaccinated against lungworm, were randomly allocated on a liveweight basis to two groups of 40 and 31 animals. At turn-out each calf in the group of 40 calves was dosed orally with a pulsed release bolus designed to deliver five doses of oxfendazole at regular intervals during a period of up to 130 days, the first dose being released about 21 days after administration. The group treated with the bolus grazed 2.4 ha and the control group grazed 3.6 ha of permanent pasture for six weeks before having additional access to similar areas of silage aftermath. The control group was treated 99 days after turn-out and when they were housed with fenbendazole (7.5 mg/kg). Faecal worm egg counts, plasma pepsinogen activities, pasture larval counts and liveweights were recorded fortnightly. Significant reductions in worm egg counts and plasma pepsinogen activities were recorded in the calves dosed with the pulsed release bolus together with significant improvements in the liveweight of younger calves compared with control animals. Pasture larval counts were lower in the fields grazed by animals treated with the bolus.

Animals↗
PubMed1991

Resistance to benzimidazole anthelmintics in small strongyles (Cyathostominae) of horses in Denmark.

This study was undertaken to establish whether anthelmintic resistance was present in nematode parasites of horses in Denmark. Sixteen horse farms were selected for faecal egg count reduction (FECR) tests to measure the efficacy of the anthelmintic used. Resistance to benzimidazole anthelmintics was found on 13 of the 16 farms, with FECR values ranging from 80.0% to -101.3%. On the remaining 3 farms FECR was 100.0%, 99.3% and 97.2%. Results of a questionnaire study on anthelmintic usage, parasite control measures and management practices showed that horses in this study were treated on average 7.1 times/year. Horse owners changed between preparations of drugs but almost only within the same class of anthelmintics. Nine owners gave an anthelmintic treatment to purchased horses before they were introduced on the farm. On 14 farms, the same paddock was grazed every year and the average stocking rate was estimated to be 2.4 horses/ha. Strategies to avoid development of anthelmintic resistance are discussed and recommendations of parasite control on horse farms are presented.

Animals↗
PubMed1979

Parasitic disease control in a residential facility for the mentally retarded.

Asymptomatic infection with either Entameba histolytica or Giardia lamblia was found in 61 per cent of the residents of a dormitory in an institution for the mentally retarded; two other dormitories had rates of 20 per cent and 22 per cent. Drug therapy was successfully undertaken in all three dormitories, and environmental improvements were introduced in the heavily infected dormitory. A one-year follow-up showed a reduction in parasitic disease in two dormitories but, in the most heavily infected dormitory, infection had returned to pretreatment levels.

Adolescent↗
PubMed2004

Ectoparasites of livestock in Europe and the Mediterranean region.

Arthropod ectoparasites can have a major impact on the productivity and welfare of livestock. In recent years, many parts of Europe have seen important changes in the nature of animal husbandry and parasite control, which have increased the need for a precise understanding of the current distribution and prevalence of livestock ectoparasites. In some cases, these changes have been associated with moves towards increased productivity, such as higher-stocking densities, large-scale rearing units, indoor confinement, reduced genetic diversity and large-scale movement of animals and, in others, with a move towards organic farming. There have also been changes in parasite control, associated with the development of new parasiticides, such as the macrocyclic lactones, and concern over the continued use of some of the older neurotoxic compounds. These changes have been exacerbated by outbreaks of endemic disease, the threats of exotic disease introduction and fears of potential changes in arthropod distribution associated with climate change. This paper therefore, reviews the current status of livestock ectoparasites in Europe and the Mediterranean region.

Animal Husbandry↗
PubMed1993

The roles of cytokines produced in the immune response to the erythrocytic stages of mouse malarias.

This review describes the role of cytokines produced by CD4+ T cells and macrophages in response to the erythrocytic stages of P. chabaudi chabaudi and other malaria infections in mice. Since virtually all compartments of the immune system are activated during the response against malaria, the variety of cytokines produced during infection is considerable. There is, however, a clear differential expression of different cytokines during primary infection. Th1-related cytokines are predominantly produced during the acute phase of infection, and lead mainly to the induction of macrophage-derived cytokines. This antibody-independent pathway is probably on the one hand, sufficient for parasite control early in infection via macrophage-associated inflammatory responses, but can, on the other hand, also lead to the pathological consequences of infection. As the infection progresses, the pattern of cytokine production shifts towards a Th2-like response. B cells play a crucial role in this process. A major consequence of this switch to a production of Th2-related cytokines later in infection would be the down-regulation of IFN-gamma-induced macrophage activation and the promotion of antibody production by mature B cells. This suggest that the mechanism of parasite control in the later stages of infection is predominantly antibody-dependent.

Animals↗
PubMed1991

Chloroquine-sensitive transplasmalemma electron transport in Tetrahymena pyriformis: a hypothesis for control of parasite protozoa through transmembrane redox.

Plasma membrane electron transport was studied in a protozoan cell, Tetrahymena pyriformis, by assaying transmembrane ferricyanide reduction and the reduction of iron compounds. The rates of ferricyanide reduction varied between 0.5 and 2.5 mumol/g dry wt. per min, with a pH optimum at 7.0-7.5. Other active non-permeable electron acceptors, with redox potentials from +360 to -125 mV, were cytochrome c, hexaammine ruthenium chloride, ferric-EDTA, ammonium ferric citrate, and indigo di-, tri- and tetrasulfonates. It was found that Tetrahymena cells can reduce external electron acceptors with redox potentials at pH 7.0 down to -125 mV. Ferricyanide stimulates ciliary action. Transmembrane ferricyanide reduction by Tetrahymena was not inhibited by such mitochondrial inhibitors as antimycin A, 2-n-heptyl-4-hydroxyquinoline N-oxide, or potassium cyanide, but it responded to inhibitors of glycolysis. Transmembrane ferricyanide reduction by Tetrahymena appears to involve a plasma membrane electron transport chain similar to those of other animal cells. As in other cells, the transmembrane electron transport is associated with proton release which may be involved in internal pH control. The transmembrane redox system differs from that of mammalian cells in a 20-fold greater sensitivity to chloroquine and quinacrine. The Tetrahymena ferricyanide reduction is also inhibited by chlorpromazine and suramin. Sensitivity to these drugs indicates that the transplasma membrane electron transport and associated proton pumping may be a target for drugs used against malaria, Trypanosomes and other protozoa.

Animals↗
PubMed1991

Control of parasitic diseases: a complementary role for vaccines and drugs.

This paper seeks to substantiate its title by discussion of three key questions: why are we attempting to develop parasite vaccines? Will we be successful? If we are, will there still be a need for chemotherapy? It concludes that: parasite vaccines are likely to be safer, cheaper and more efficacious as prophylactics than antiparasite drugs; in time vaccines will be developed for some but not all human parasitic diseases; at least in the short and medium term, drugs will be needed for those already infected and for those for whom, for whatever reason, a vaccination strategy fails.

Animals↗