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At least 19 recordsLinked to original sources

PubMed1987

Heterologous antagonistic and synergistic interactions between helminths and between helminths and protozoans in concurrent experimental infection of mammalian hosts.

Experimental concurrent infection with two or more parasite species in mammalian host models may result in heterologous antagonistic and synergistic interactions ranging in magnitude from reduced/enhanced growth and fecundity to blockage/enhancement of establishment/expulsion. With some exceptions only, there is a reasonable correlation between the levels of interaction monitored by parasitological and by clinico-pathological parameters. Heterologous antagonistic interactions mediated by functional and specific immunological cross-reactivity occur between closely related parasite species exhibiting a marked immunobiological similarity. In contrast, antagonistic interactions between antigenetically more remote species of helminths, protozoan-induced resistance to helminth infection and helminth-induced suppression of concurrent protozoan infection generally appear mediated by immunologically non-specific factors like macrophage activation and inflammatory reactions. Synergistic heterologous interactions between helminths, helminth-induced enhancement of concurrent protozoan infection and interference with the development and maintenance of resistance to helminth infection in response to concurrent protozoan infection are generally thought to be mediated by non-specific parasite-induced immunosuppression. Concurrent experimental infection is very complex. There are problems and limitations in extrapolating from experimental studies on concurrent infection in laboratory animals to natural polyparasitism. This fact, coupled with the complex influence of ecological factors on the pattern and frequency of concurrent natural infection means that major consequences of natural concurrent parasite infection have not been definitively demonstrated. Appropriately planned and controlled field studies and further laboratory experiments on primate and domestic animal models are imperative for elucidation of the importance of heterologous interactions in concurrent parasite infection for the disease pattern in man and domestic stock. Experimental studies hitherto conducted on concurrent parasite infection pointing to natural heterologous interactions may be a valuable starting point for further studies.

Animals↗

PubMed2006

Coincident filarial, intestinal helminth, and mycobacterial infection: helminths fail to influence tuberculin reactivity, but BCG influences hookworm prevalence.

The prevalence of helminth and tuberculosis infections is high in South India, whereas Bacille-Calmette-Guerin (BCG) vaccine efficacy is low. Our aim was to determine whether concurrent helminth infection alters the ability to mount a delayed-type hypersensitivity response to tuberculin. In a cross-sectional study in southern India, individuals 6-65 years of age were screened for intestinal helminths, circulating filarial antigenemia, tuberculin reactivity, active tuberculosis, and history of BCG vaccination; 54% were purified protein derivative (PPD) positive, 32% had intestinal helminth infection, 9% were circulating filarial antigen positive, and 0.5% had culture-confirmed active tuberculosis. Only age and BCG vaccination were significantly associated with PPD reactivity; however, BCG vaccination was associated with a lower prevalence of hookworm infection relative to those without prior BCG vaccination. Neither intestinal helminth infection nor filarial infection was associated with diminished frequencies of PPD positivity. Our findings suggest that preceding helminth infection does not influence significantly the delayed-type hypersensitivity response to tuberculin.

Adolescent↗

PubMed1989

A survey of helminths in domestic cats in the Pretoria area of Transvaal, Republic of South Africa. Part 1: The prevalence and comparison of burdens of helminths in adult and juvenile cats.

The helminths found in 1,502 necropsied cats were examined. The findings indicated that 65% of the cats were infested. The most prevalent helminths encountered were Ancylostoma tubaeforme (41%), Ancylostoma braziliense (25%), Dipylidium caninum (23%), Toxocara cati (11%), Taenia taeniaeformis (7.7%), Ancylostoma caninum (3.3%), Joyeuxiella fuhrmanni (2.5%), Ancylostoma ceylanicum (1.4%), and Physaloptera praeputialis (1.3%). The following helminths were recorded in fewer than 1% of the cats: Centrorhynchus spp., Pterygodermatites spp., Toxocara canis, Aleurostrongylus abstrusus and Vogeloides spp., This is the first record of the lungworms, A. abstrusus and Vogeloides spp. in cats in the Republic of South Africa. The helminths in adult and juvenile cats are compared. Of the cestodes, Joyeuxiella fuhrmanni (4%) and Taenia taeniaeformis (12%) are more prevalent in adult cats. Dipylidium caninum is marginally more common in adults (24%), and is the most common helminth in juvenile cats, being present in 21% of cases. More adult cats have Ancylostoma tubaeforme (58%), Ancylostoma braziliense (36%), Ancylostoma ceylanicum (2.4%) and Physaloptera praeputialis (1.9%) than do juvenile cats. However, juvenile cats were found to harbour more Toxocara cati (41%), Toxocara canis (0.5%) and Ancylostoma caninum (5.2%). Juvenile cats harbour appreciable numbers of both cestodes and nematodes, thus any treatment should be aimed at the elimination of both, with a broad spectrum anthelmintic.

Age Factors↗

PubMed1982

[Studies on chemotherapy of parasitic helminths (III). Effects of tuberostemonine from Stemona japonica on the motility of parasitic helminths and isolated host tissues (author's transl)].

Effects of tuberostemonine (TS), an alkaloid from Stemona japonica, on the motility of parasitic helminths and isolated frog rectus and mouse ileum were studied. 1) TS (6.7 X 10(-6) approximately 2 X 10(-5) M) paralyzed the motility of Angiostrongylus cantonensis. 2) TS (6.7 X 10(-5) M) showed contractive effects on the motility of Dipylidium caninum and Fasciola hepatica. 3) Treatment with TS (6.7 X 10(-5) approximately 4.8 X 10(-4) M) had little effect on the motility of Schistosoma japonicum. 4) TS (6.7 X 10(-5) M) paralyzed the motility of the mouse isolated ileum preparation. 5) TS (6.7 X 10(-7) 6.7 X 10(-6) M) stimulated the twitch response induced by guanidine (2.5 X 10(-3) M) in the frog isolated rectus preparation. 6) Eserine and TS acted antagonistically on all preparations with the the exception of S. japonicum. 7) TS and strychnine were antagonistic in isolated host tissues, whereas these compounds acted similarly on parasitic helminths. Thus, it is suggested that some of the experiential effects of the crude extracts of Stemona such as the anthelmintic effects are caused through the action of TS on parasitic helminths and host tissues.

Alkaloids↗

PubMed1982

[Studies on chemotherapy of parasitic helminths (IV). Effects of alkaloids from Sophora flavescens on the motility of parasitic helminths and isolated host tissues (author's transl)].

Effects of N-methylcytisine (N-MC) and matrine (Mat), alkaloids from Sophora flavescens on the motility of parasitic helminths and isolated frog rectus and mouse ileum were studied. 1) The motility of Angiostrongylus cantonensis was affected spastically by N-MC (1.2 X 10(-6) approximately 1.2 X 10(-4) M), but paralytically by Mat (10(-5) approximately 10(-4) M). 2) The motility of Dipylidium caninum and Fasciola hepatica was affected paralytically by N-MC (1.2 X 10(-4) approximately 1.2 X 10(-3) M), but spastically by Mat (10(-4) approximately 10(-3) M). 3) Treatment with N-MC (10(-3) M) and Mat (8 X 10(-4) M) had little effect on the motility of Schistosoma japonicum. 4) Both N-MC (1.2 X 10(-5) approximately 2.4 X 10(-5) M) and Mat (10(-4) M) stimulated the twitch response induced by guanidine (2.5 X 10(-5) M) in the frog isolated rectus preparation. 5) The motility of the mouse isolated ileum preparation was affected paralytically by N-MC (1.2 X 10(-5) approximately 1.2 X 10(-4) M), but spastically by Mat (10(-4) approximately 10(-3) M). Thus, N-MC and Mat acted antagonistically on all the preparations with the exception of the frog rectus preparation. From the results on interactions between these alkaloids and known neuropharmacological agents, it is suggested that the effects of both alkaloids are elicited through a neuropharmacological mechanism in parasitic helminths and host tissues.

Alkaloids↗

PubMed2004

Cutting edge: dendritic cells copulsed with microbial and helminth antigens undergo modified maturation, segregate the antigens to distinct intracellular compartments, and concurrently induce microbe-specific Th1 and helminth-specific Th2 responses.

To examine the ability of dendritic cells (DC) to discriminate between helminth and microbial Ag and induce appropriately polarized Th responses, mouse DC were copulsed with the helminth Ag, schistosome egg Ag (SEA), along with the bacterium Proprionebacterium acnes, Pa, and transferred into wild-type mice. Strikingly, SEA/Pa-copulsed DC induced concurrent Pa-specific Th1 (but not Th2) responses and SEA-specific Th2 (but not Th1) responses. Although DC exposed to both Ag undergo many of the maturation-associated changes that accompany exposure to Pa alone, Pa-induced IL-12 production was inhibited by SEA. Examination of Ag uptake revealed that SEA and Pa are acquired via discrete pathways and enter nonoverlapping intracellular compartments. Data suggest that segregation of SEA and Pa into distinct compartments, coupled with SEA-induced modifications of the DC maturation pathway, are significant components of the ability of DC to interpret signals inherent to SEA and Pa and induce appropriately polarized Th responses.

Animals↗

PubMed1994

The helminthic parasites of rodents in Dakahlia Governorate, with reference to their Egyptian helminth fauna.

No doubt, rodents are among the most important reservoirs of zoonotic diseases. This paper aimed to survey the helminth fauna of the different species of rodents in Dakahlia Governorate. Eight species of rodents were encountered in the different centers examined. A total of fifteen species of helminthic parasites were found. They belong to four classes: Trematoda five species: H. heterophyes, H. pumilio, H. yokogawai, S. tridactyla and E. callawayensis, Cestoidea three species: H diminuta, H. nana and T. taeniaeformis, Nematoda six species: A. cantonensis, T. muris, C. hepatica, S. obvelata, S. muris, S. ratti, and Archiacanthocephala one species: M. moniliformis. The medical and/or veterinary importance of these parasites were discussed. It was concluded that rodents are the most serious source of zoonotic parasites.

Animals↗

PubMed1991

[Main features of helminth parasitism in cattle in Ituri (Haut-Zaire). III. Geographic distribution and prevalence of the main helminths].

A necropsic survey, carried out in eleven slaughterhouses in Ituri (Haut-Zaïre), has permitted to define the geographic distribution and prevalences of the main cattle helminths. Trematodes, except the paramphistomes, had a very heterogeneous distribution. Prevalence of Fasciola gigantica ranged from 9 to 72% according to the sites, but these variations were not linked to topographic or climatologic parameters. The infection with Schistosoma bovis was much variable as well (12.5 to 72%) and seemed absent from the central high altitude area. The occurrence of Dicrocoelium hospes was restricted to the northern part of Ituri with a moderate prevalence of about 35%. By contrast, nematodes had a fairly homogeneous distribution in Ituri. Prevalences were high for gastro-intestinal strongyles of the following genera, Haemonchus, Cooperia and Oesophagostomum (over 60%). Cysticercosis (Cysticercus bovis) occurred in 10 to 14% of cattle in the middle and south areas of Ituri whereas the north areas were nearly free.

Animals↗

PubMed1990

[Dominant characteristics of helminth parasitism in cattle in Ituri (Haut-Zaire). I. The helminth fauna].

The identification of cattle helminths in Ituri was carried out by post mortem examinations in slaughterhouses and tracer calves. The thirty diagnosed species were typical of wet tropical areas of Africa. The presence of Dictyocaulus viviparus, Ostertagia ostertagi and Haemonchus similis and the absence of Echinococcus granulosus constituted the original features of this inventory.

Animals↗

PubMed1983

Studies on the parasitic helminths of slaughtered animals in Iraq. I. Parasitic helminths of the liver of herbivores.

The livers and lungs of 580 sheep, 160 goats, 418 cattle, 50 camels and 48 buffaloes slaughtered in Baghdad in April-July, 1981 were examined for helminth parasites; 14.3% of the sheep, 0.6% of the goats, 18.2% of the cattle, 72.0% of the camels and 8.3% of the buffaloes were infected with trematodes and cestodes. Dicrocoelium dendriticum is reported from the livers of sheep in Iraq for the first time.

Animals↗

PubMed1958