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PubMed1999

Interactions between dietary fibre, endo-parasites and Lawsonia intracellularis bacteria in grower-finisher pigs.

Samples of faeces and feed were collected from grower and finisher pigs kept on 25 commercial breeder-finisher units in the West-Midlands region of England. Faecal samples were examined for parasite eggs (Ascaris suis, Trichuris suum and strongylid species) using faecal flotation; and for Lawsonia intracellularis bacteria using the polymerase chain reaction. Feed samples were subjected to proximate analysis for energy, protein and fibre content and enzymic colorimetry for levels of non-starch polysaccharides (NSPs). Characteristics relating to housing, feeding and dung disposal systems and husbandry practices were recorded for each farm and assessed for their association with the presence of parasites and L. intracellularis at the herd level. Ascaris eggs were identified in 8% of herds, Trichuris eggs in 20% of herds and in strongylid eggs (Oesophogostomum and/or Hyostrongylus) in 44% of herds. Lawsonia intracellularis was detected in 15% of herds investigated. Herds positive for Trichuris and Ascaris had significantly lower levels of digestible energy and higher levels of neutral detergent fibre, total and insoluble NSPs in their diets than negative herds (p < 0.05). Housing weaners on slatted floors was associated with a significant decreased risk of parasite infection in grower-finishers (odds ratio = 0.09, p = 0.04) compared to housing on solid floors. The use of grower diets high in NSPs was associated with an increased risk of Trichuris infection (odds ratio = 27.6, p = 0.007). There was also an association at the herd level between infection with L. intracellularis and the presence of Trichuris eggs (odds ratio = 17.43, p = 0.069). It is concluded that control of dietary fibre intake (NSPs in particular) for growers and environmental hygiene (dung removal) for weaners appear to be the most important factors controlling parasite infection in grower-finisher pigs in the UK at present. The current move towards more straw based systems is thus likely to exacerbate the influence of these factors and is likely to result in increased parasite infection in grower-finisher pigs in the UK.

Animal Feed↗
PubMed2006

Stronger host response per parasitized erythrocyte in Plasmodium vivax or ovale than in Plasmodium falciparum malaria.

OBJECTIVE AND METHODS: Fever tends to start at a lower level of parasitemia in Plasmodium vivax or ovale than in P. falciparum malaria, but hyperparasitemia and complications are more likely to occur in P. falciparum malaria. Therefore, we compared the relationship between parasitemia and host response parameters before therapy in 97 patients with P. faciparum malaria (18 with complications), and 28 with P. vivax or ovale malaria. RESULTS: In both types of malaria, parasitemia correlated with blood levels of tumour necrosis factor alpha (TNF-alpha), lactate dehydrogenase (LDH), Thrombin-antithrombin III (TAT) and elastase, and these parameters were higher in P. falciparum malaria than in P. vivax or ovale malaria. In contrast, the ratios of TNF-alpha, TAT, elastase, and LDH per parasitized erythrocyte were higher in P. vivax or ovale malaria than in uncomplicated P. falciparum malaria. They were lowest in complicated disease. Multivariate regression analysis confirmed that parasitemia did not affect these differences. CONCLUSION: The host response may reach full strength at lower parasitemia in Plasmodium vivax or ovale, than in P. falciparum malaria. With hyperparasitemia in P. falciparum malaria, the host response seems to be unable to control parasite multiplication.

Animals↗
PubMed1985

Prevalence of benzimidazole-resistant small strongyles in horses in a southeastern Pennsylvania practice.

A survey was conducted to determine the prevalence of benzimidazole (BZ)-resistant small strongyles in horses in a southeastern Pennsylvania practice. Resistant parasites were found in 291 of 342 horses surveyed. Anthelmintic practices and pasture management factors in use for 3 to 6 years did not correlate with the presence of resistant small strongyles. Benzimidazole-resistant small strongyles were recovered in horses that had been treated alternately with BZ and non-BZ products and in horses receiving BZ products as infrequently as twice a year. However, inasmuch as the horses may have been infected with resistant small strongyles before the various anthelmintic schedules were implemented, it was not possible to attribute BZ-resistance to any particular pattern of drug use. Fifty-one (14.9%) horses had BZ-susceptible small strongyles: these horses were on poor overall parasite control programs and had received BZ products no more than once a year. Benzimidazole-piperazine and non-BZ drugs were effective in herds infected with BZ-resistant small strongyles.

Animals↗
PubMed1997

Specific inhibitory effect of 3-deazaneplanocin A against several Leishmania mexicana and L. braziliensis strains.

The growth inhibitory effect of 3-deazaneplanocin A (c3NpcA) was tested against some pathogenic members of the family of American Trypanosomatidae. Under our culture conditions, c3NpcA displayed a strongly and uniformly leishmanistatic effect on all 23 American Leishmania (L. mexicana and L. brasiliensis) strains in the study (mean dose producing 50% inhibition compared with control parasite growth [ID50] = 96 ng/ml, 0.32 microM), but showed no inhibition against the several T. cruzi and T. rangeli strains tested with concentrations up to 10,000 ng/ml. This compound also induced a substantial expansion of the intracellular pools of both S-adenosylhomocysteine (AdoHcy) and S-adenosylmethionine (AdoMet), as well as a significant diminution of the AdoMet:AdoHcy ratio. Strong AdoHcy hydrolase activity was detected in American Leishmania promastigotes. At at a dose of 200 ng/ml, c3NpcA inhibited S-adenosyl-L-3H-methylmethionine and 3-thymidine incorporation by promastigotes after four days incubation in the presence of the drug. At a dose of 100 ng/ml, c3NpcA eliminated approximately 56% of the L. mexicana and L. brasiliensis from infected human macrophages, compared with simultaneously cultivated controls. Two schedules of 10 consecutive intraperitoneal injections of c3NpcA, with doses ranging from 0.5 to 1.5 mg/kg/day, significantly reduced development of cutaneous leishmanial infection produced in inbred BALB/c mice by L. b. guyanensis inoculation, although a few parasites remained at the inoculation site.

Adenosine↗
PubMed2001

Morphological changes during conoid extrusion in Toxoplasma gondii tachyzoites treated with calcium ionophore.

Treatment of tachyzoites of Toxoplasma gondii with the calcium ionophore A23187 induced dramatic ultrastructural changes that were observed by light and electron microscopy. Light microscopy showed a higher percentage (22%) of tachyzoites with the conoid extruded when compared to control parasites. Electron microscopy confirmed the conoid extrusion by both transmission and scanning electron microscopy. Freeze-fracture replicas showed that the plasma membrane adjacent to cytoplasmic dense granules appeared devoid of intramembranous particles. Membrane-limited vesicles and filopodium-like structures at the cell surface were observed in treated cells. 3-D reconstruction from serial sections confirmed the data and showed a heterogeneity in dense granule shape not reported in control cells.

Animals↗
PubMed1991

Distribution patterns of Opisthorchis viverrini within a human community.

This paper describes patterns of infection with Opisthorchis viverrini within a human community assessed by egg count, parasite-specific antibody levels and worm burden determined by expulsion chemotherapy. All three measurements increased significantly with age, reaching a plateau in young adults. There were no significant sex-associated differences in the prevalence or intensity of infection, antibody levels, or in the frequency of heavy worm burdens. A striking 81.5% of the total Opisthorchis population and 74% of the total egg output were expelled by the most heavily infected 10% of the humans sampled. This extreme over-dispersion, together with recent findings that hepatobiliary disease frequently accompanies heavy infections, argues that the priority for community-based parasite control programmes should be to maximize treatment and health promotion efforts toward heavily infected individuals.

Adolescent↗
PubMed2001

[Escape mechanism of intracellular parasitic bacteria and prospect of new approach to infection control].

Intracellular parasitic bacteria are capable of escaping from the intracellular killing inside macrophages by virtue of highly sophisticated molecular mechanism. Because of the escape from phagocytic defense, infection caused by these bacteria is difficult to be controlled even in the presence of normal host defense system. In order to understand the mechanism of intracellular parasitism of particular types of bacteria, the basic mechanism of intracellular killing inside phagocyte and the strategy of escape by some representative intracellular bacteria are reviewed. Based on the mechanism of T-cell dependent protective immunity, some possible approaches to the infection by intracellular bacteria, especially to tuberculosis, have been discussed.

Animals↗
PubMed2006

Comparison of efficacy of moxidectin and ivermectin in the treatment of Strongyloides fulleborni infection in rhesus macaques.

BACKGROUND: Strongyloides infection may result in clinical disease or confound experimental protocols that utilize non-human primates. There is presently a Strongyloides fulleborni infection rate of approximately 27% in the Tulane National Primate Research Center's breeding colonies despite the routine therapeutic and prophylactic use of ivermectin. METHODS: A study was conducted to determine if moxidectin treatment offers advantages to the intestinal parasite control program. A total of 150 rhesus macaques (Macaca mulatta) that were removed from the breeding colonies due to illness were selected for the study. The animals were randomly assigned to treatment groups with 75 receiving ivermectin and 75 receiving moxidectin. Egg counts were performed on fecal samples collected pre- and post-treatment. RESULTS: Both treatments resulted in decreases in the number of eggs/g in the post-treatment sample as compared with the pre-treatment sample; however, no significant difference was found between treatment groups. CONCLUSIONS: With the data demonstrating a similar efficacy in both ivermectin and moxidectin treated macaques, the benefit of moxidectin treatment relates to biosafety and topical application.

Administration, Topical↗
PubMed2004

Enhanced replication of Leishmania amazonensis amastigotes in gamma interferon-stimulated murine macrophages: implications for the pathogenesis of cutaneous leishmaniasis.

During Leishmania major infection in mice, gamma interferon (IFN-gamma) plays an essential role in controlling parasite growth and disease progression. In studies designed to ascertain the role of IFN-gamma in Leishmania amazonensis infection, we were surprised to find that IFN-gamma could promote L. amazonensis amastigote replication in macrophages (Mphis), although it activated Mphis to kill promastigotes. The replication-promoting effect of IFN-gamma on amastigotes was independent of the source and genetic background of Mphis, was apparently not affected by surface opsonization of amastigotes, was not mediated by interleukin-10 or transforming growth factor beta, and was observed at different temperatures. Consistent with the different fates of promastigotes and amastigotes in IFN-gamma-stimulated Mphis, L. amazonensis-specific Th1 transfer helped recipient mice control L. amazonensis infection established by promastigotes but not L. amazonensis infection established by amastigotes. On the other hand, IFN-gamma could stimulate Mphis to limit amastigote replication when it was coupled with lipopolysaccharides but not when it was coupled with tumor necrosis factor alpha. Thus, IFN-gamma may play a bidirectional role at the level of parasite-Mphi interactions; when it is optimally coupled with other factors, it has a protective effect against infection, and in the absence of such synergy it promotes amastigote growth. These results reveal a quite unexpected aspect of the L. amazonensis parasite and have important implications for understanding the pathogenesis of the disease and for developing vaccines and immunotherapies.

Animals↗
PubMed2004

Vaccination protects B cell-deficient mice against an oral challenge with mildly virulent Toxoplasma gondii.

Prior studies have demonstrated that B cells are important components of protection in vaccinated mice challenged intraperitoneally with a highly virulent type I strain of Toxoplasma gondii parasites. However, it is not known whether B cells are required for vaccinated mice to successfully resist a more physiologically relevant challenge infection with a mildly virulent type II strain of T. gondii. To investigate that question, we vaccinated B cell-deficient C57BL/6 (microMT) mice with an attenuated strain of T. gondii and challenged them with a potentially lethal oral dose of type II T. gondii cysts. Vaccinated microMT mice survived the challenge as well as vaccinated B6 controls, controlled parasites equally well in critical tissues, produced equivalent levels of mRNA for several type 1 cytokines, and exhibited comparably mild histopathology. Thus, a vaccine can protect against infection with a mildly virulent type II strain of T. gondii in the absence of a B cell-dependent immune response.

Animals↗
PubMed2004

Identification of a serine protease gene expressed by Myxobolus cerebralis during development in rainbow trout Oncorhynchus mykiss.

Serine proteases have been recognized as key factors in parasite physiology and disease development. We have identified a serine protease gene from Myxobolus cerebralis, MyxSP-1, the myxozoan parasite causing whirling disease in salmonid fishes. The amino acid sequence, as deduced from the cDNA sequence, included a catalytic residue arrangement similar to that of the chymotrypsin family of serine proteases. A real-time TaqMan polymerase chain reaction (PCR) analysis revealed differences in the transcription levels for the chymotrypsin-like protease as found in early, intermediate, and late developmental stages of the parasite in experimentally-infected rainbow trout Oncorhynchus mykiss. MyxSP-1 transcription differed between individual tissues at each sampling point and in the same tissues over time (p < 0.0001). A nonradioactive mRNA in situ hybridization (ISH) protocol was developed to detect MyxSP-1 transcripts. Using a mixture of 3 digoxigenin-labeled antisense mRNA probes, MyxSP-1 transcription was observed in developmental stages of the parasite during the acute and chronic phases of the disease over a 240 d time period in infected rainbow trout tissues. MyxSP-1 transcription observed by ISH in cartilage and as associated with cartilage destruction was consistent with our real-time TaqMan PCR findings that demonstrated high levels of MyxSP-1 transcription during lesion development. Identifying genes encoding these enzymes and characterization of their functions can lead to the development of new chemotherapeutic protocols and vaccine approaches to control parasitic diseases.

Amino Acid Sequence↗
PubMed1989

Llama herd health.

Herd health programs for llama owners offer veterinarians the opportunity to provide preventive care to an expanding market. Some aspects of llama herd health programs are unique but should be based on herd health principles used for other livestock species. Vaccinations, parasite control, nutritional consultation and reproductive examinations, coupled with feet and teeth care, are some areas to cover in herd health programs. Each herd will have slightly different requirements and the program should be tailored to the goals of the producer.

Animal Husbandry↗
PubMed1990

[A survey on the epidemiological factors of clonorchiasis in the Pohang industrial belt along the Hyungsan river, Kyongsangbuk-do].

The employees at the Pohang industrial area, where Clonorchis sinensis has been known to be endemic along the Hyungsan River, were examined parasitologically for clonorchiasis and a part of the infected cases were surveyed with a questionnaire to outline the recent infection status of C. sinensis and epidemiological parameters in the area. Total of 3,180 cases were tested by intradermal inoculation of C. sinensis antigen (Green Cross Co., Korea), and 834 (26.2%) were found positive. Out of the positive cases, 598 were subjected to fecal examination for helminth ova. The examination revealed 129 (21.6%) ova positive cases of C. sinensis, and Trichuris trichiura 1.7%, Ascaris lumbricoides 0.3%, and Metagonimus yokogawai 0.2%. The questionnaire analysis showed some significant differences between the infected and non-infected (control) groups. The infected cases were less educated than the control, and they lived at the closer area to the river, and most of them lived there over 20 years. Also they preferred eating raw fresh water fish. Most of the detected cases were treated with praziquantel and found negative for the eggs in 85.3% of them 1 year after the treatment. The present data reveal markedly decreased endemicity of clonorchiasis compared with previous prevalence rates but still clonorchiasis is endemic in the Hyungsan river basin. A comprehensive measure including case detection, treatment and education for parasite control should be applied to control clonorchiasis in such endemic areas.

Adult↗
PubMed2001

Gastrointestinal nematodes of cattle in the northeastern US: results of a producer survey.

A questionnaire covering management practices and producer perception of the effects of gastrointestinal nematode infections was sent to dairy and beef producers in the northeastern US. The mailing list was derived from membership in grazing groups and attendance at grazing events. A final total of 474 responses were suitable for analyses. These responses covered 14 states, but for the purpose of analysis were broken into five groups: New England (NE), Vermont (VT), New York (NY), Pennsylvania (PA), and south and west (S and W) of Pennsylvania. Two-thirds of the responses were from dairy producers. The average number of animals for the farms was 50 cows, 27 heifers, and 20 calves. The average acreage used for grazing was 70 acres, and about two-thirds of the responses used rotational grazing for at least the cows. About one-half of the rotational grazers had been practicing rotational grazing for more than 5 years. Most rotational programs for cows involved a daily rotation, but the rotational interval for other age groups was longer. There was a difference of about 2 months (5.25-7.27) in the length of the grazing season as one moved from New England to south and west of Pennsylvania. Parasite control practices varied greatly by location and animal class. Most producers used anthelmintics one to two times per year, but 10-30% of responses said they did not deworm their cattle. The most common time to deworm was in the spring, and the second most common time was the fall. Between 10 and 20% of respondents reported deworming as a response to decreased productivity or body condition. The use of anthelmintics increased as the location moved from New England to south and west of Pennsylvania. Producer perception of parasite effects was closely related to their anthelmintic use, and also increased as the location moved to the south, and is most likely the result of the increased length of the grazing season. Of producers who ascribed estimated a cost of the parasite, the majority estimated this cost to be between US$ 5 and 20 per animal per year.

Animal Husbandry↗
PubMed1998

Passive transfer of growth-inhibitory antibodies raised against yeast-expressed recombinant Plasmodium falciparum merozoite surface protein-1(19).

Purified rabbit immunoglobulin raised against yeast-expressed recombinant FVO or 3D7 Plasmodium falciparum merozoite surface protein-1 (MSP-1) 19k-D C terminal fragment (MSP-1(19)) was transfused into malaria-naive Aotus nancymai monkeys that were immediately challenged with FVO asexual stage malaria parasites. Control monkeys received rabbit immunoglobulin raised against the sexual stage antigen Pfs25 or Aotus hyperimmune serum obtained from monkeys immunized by P. falciparum infection and drug cure. Passive transfer of rabbit anti-MSP-1(19) failed to protect against homologous or heterologous challenge and, when compared with negative controls, there were no differences in prepatent periods or time to treatment. Interestingly, rabbit anti-MSP-1(19), but not anti-Pfs25, immunoglobulin, and immune monkey serum prevented the development of antibodies directed against MSP-1(19) fragment by infected monkeys, indicating that the antibodies were reactive with native MSP-1(19) antigen in vivo. The prepatent period and time to treatment was greatly delayed in the two monkeys that received Aotus immune serum, both of which developed a chronic intermittent low level infection. In vitro parasite growth inhibition assays (GIAs) confirmed the presence of inhibitory activity (40% maximum inhibition) in concentrated anti-MSP-1(19) immunoglobulin (4.8 mg/ml), but the peak concentrations we achieved in vivo (1 mg/ml) were not inhibitory in vitro. Subinhibitory levels of anti-MSP-1(19) antibodies achieved by passive transfer were not protective against P. falciparum challenge.

Animals↗
PubMed2001

Socio-economic and environmental protective/risk factors for severe malaria in Thailand.

We conducted a cross-sectional study to identify the socio-economic and environmental protective/risk factors for severe malaria in Thailand. Forty-six cases of severe malaria, 72 cases of non-severe malaria with high parasite biomass and 40 mild malaria cases were included. When comparing severe malaria and non-severe malaria with high parasite biomass, specific logistic regression models showed a significant protective effect for helminths, adjusted odds ratio 0.24 (0.07-0.78) for low body mass index (BMI), adjusted odds ratio 0.11 (0.02-0.58). When comparing severe and mild malaria, a longer residence duration, adjusted odds ratio 0.36 (0.09-0.83) and the use of antimalarial self-medication, adjusted odds ratio 0.08 (0.009-0.84) were associated with protection from severe malaria. Using stepwise logistic regression with all the variables inserted in the model yielded similar results. These findings suggest specific immunity and self-medication control parasite multiplication whereas helminths and malnutrition more specifically affect the pathogenesis of severe malaria.

Adult↗
PubMed1996

The prevalence of anthelmintic resistance in nematode parasites of sheep in southern Latin America: Paraguay.

This survey to detect anthelmintic resistance in nematode parasites of sheep was conducted on 11 farms in the Occidental and 26 farms in the Oriental Regions of Paraguay using the faecal egg count reduction test (FECRT). The anthelmintic groups tested were the benzimidazoles, levamisole and avermectins (both oral and injectable). Overall the levels of resistance were 73%, 68%, 73% and 47%, respectively. Levels of resistance were similar for all three important nematode genera, viz. Haemonchus contortus, Ostertagia and Trichostrongylus. This survey clearly indicates that a large, and ever increasing, proportion of sheep farmers are rapidly approaching the time when they will have exhausted all chemotherapeutic options to control parasites. Unless they face having to abandon their sheep farming operations, radical changes will need to be implemented with urgency.

Animals↗
PubMed2006

Antibody responses to Ascaris-derived proteins and glycolipids: the role of phosphorylcholine.

In addition to proteins, glycolipids can be targets of antibody responses and contribute to host-pathogen interaction. Following the structural analysis of Ascaris lumbricoides-derived glycolipids, the antibody responses of a group of children with no, light and heavy infections were analysed. The role of the phosphorylcholine moiety, present on Ascaris glycoproteins and glycolipids, in antibody reactivity of these infected individuals was determined. Children carrying heavy infections showed highest IgG reactivity to glycolipids compared to lightly or non-infected children. Substantial IgG antibody reactivity to both (glyco)proteins and glycolipids was found to be directed to the phosphorylcholine moiety as determined by either removal of this group or a competition assay. This was most pronounced for glycolipids, where removal of the phosphorylcholine moieties by hydrofluoric acid treatment abrogated IgG antibody reactivity. Measurement of IgG4 and IgE isotypes showed no IgG4 reactivity to Ascaris glycolipids, but raised IgE responses were detected in subjects with light or no Ascaris infections, suggesting that IgE responses to glycolipids may play a role in controlling parasite burden. Differences found in antibody profiles to glycolipids and (glyco)proteins, indicate that these different classes of compounds may have distinct roles in shaping of and interacting with humoral immune responses.

Animals↗