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PubMed1985

Recent advances in malaria parasite cultivation and their application to studies on host-parasite relationships: a review.

The continuous cultivation of the erythrocytic stages of Plasmodium falciparum was achieved in 1976 and techniques have now also been developed for continuous cultivation of these stages from P. knowlesi, P. fragile, P. inui, P. cynomolgi and P. berghei. The requisite conditions for successful cultivation are described. Gametes of certain isolates of P. falciparum can also now be produced in vitro and these are infective to mosquitos, leading to normal development of the parasite.The successful cultivation in vitro of the exoerythrocytic stages of P. berghei and P. vivax was achieved in 1981 and 1983, respectively. These cultures give rise to infective merozoites.There have been no significant advances in the in vitro cultivation of the sporogonic stages of malaria parasites for the last 15 years, although studies indicate that the in vitro cultivation of these stages from gamete to sporozoite stage is theoretically possible.The application of cultivation techniques to the study of parasite epidemiology is discussed. To date the major epidemiological impact has related to their use for measuring the incidence and spread of drug resistance. Applications to the study of the genetics of drug resistance, antigen production, development of tests for protective immunity, and drug development and screening are reviewed.

Animals↗
PubMed1994

[Development of parasitism in Nematoda and formation of host-parasite relationships].

Nowadays the developmental process of parasitism within the nematodes of animals and plants also takes place. Rhabditida group coming from the soil saprophytic forms is an example of such evolutionary process in statu nascendi. The conditions and ways towards the close relationships between two organisms, leading from the commensalism and facultative parasitism to the obligatory one have been presented.

Animal Population Groups↗
PubMed1998

[Imported arthropod-borne parasites and parasitic arthropods in dogs. Species spectrum and epidemiologic analysis of the cases diagnosed in 1995/96].

Between January 1995 and December 1996 nonendemic or only regionally occurring arthropodborne parasites including ehrlichiae and parasitic arthropods in Germany were detected in 484 dogs, whereby at least 15 species were involved. Listed in decreasing order, Leishmania infections occurred most frequently, followed by infections/infestations with Babesia canis, Ehrlichia canis, Rhipicephalus sanguineus, Dirofilaria immitis and Dermacentor reticulatus. The other species, namely Babesia gibsoni, Trypanosoma congolense, Hepatozoon canis, Ehrlichia platys, Dirofilaria repens, Dipetalonema reconditum, Dermacentor marginatus, Boophilus microplus and Cordylobia anthropophaga were demonstrated in a few or single dogs. Irrespective of the pathogen-species, most of the dogs had travelled with their owners to Mediterranean countries or to Portugal or had been imported from there. Infections with B. canis were diagnosed very frequently in dogs returning from Hungary. Of the 28 dogs with previous residence in Germany only, twelve and four animals were infected with B. canis and E. canis, respectively, and seven and five dogs were infested with R. sanguineus and D. marginatus, respectively.

Animals↗
PubMed1982

Large-scale management systems and parasite populations prevalence and resistance of parasitic agents in animal effluents and their potential hygienic hazard.

Keeping large numbers of animals in large-scale, pseudo-industrial units poses similar problems to the overstocking of small farms within any one area, as far as the disposal of animal effluents is concerned. The prevalence of parasites in pigs, poultry and cattle on large-scale farms is listed, and examples of the resistance of their exogenic stages are given. The possibilities of transmission to individuals of the same species or to other species including man are evaluated. Guidelines for safe or restricted disposal of the effluents as fertilizers for different plant crops are given. On recycling effluents as animal food, no problems should arise from the parasitologist's point of view if poultry manure is fed to pigs or cattle or if swine or cattle effluents are fed to poultry. Other combinations are hazardous.

Animals↗
PubMed1985

Secreted and circulating antigens of the filarial parasite Brugia pahangi: analysis of in vitro released components and detection of parasite products in vivo.

A range of excretory-secretory (ES) antigens have been characterised following in vitro culture of adult Brugia pahangi filarial nematodes in serum-free medium. Analysis by radioiodination, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and immunoprecipitation of purified macromolecules with antibodies from human and experimental animal infections reveals both host and parasite components. Two host molecules appear by molecular weight and immunoprecipitation analysis to be immunoglobulin and serum albumin, presumed to be taken up from the jird host from which adult worms were recovered. A further prominent component, of 19 kDa, reacts with neither anti-host nor anti-filarial antibodies, and may represent a non-immunogenic parasite product. Three additional bands, although less intensely radiolabelled, did prove to be consistently antigenic, with apparent molecular weights of 15, 29 and 40 kDa. A further ES antigen, which does not take up radio-iodine or lend itself to electrophoretic analysis, has also been detected. This molecule reacts in a immunoradiometric assay in which monoclonal antibody directed against a repetitive epitope acts both to capture and indicate antigen presence. The same antibody, Bp-1, may also be employed to detect circulating antigen in the serum of animals experimentally infected with Brugia pahangi, and in the serum of patients with each of the three species of human lymphatic filariasis, Brugia malayi, Brugia timori and Wuchereria bancrofti.

Animals↗
PubMed1995

Parasitism and chromosome dynamics in protozoan parasites: is there a connection?

Genomic plasticity is a hallmark of many protozoan parasites, including Plasmodium spp, Trypanosoma spp, Leishmania ssp and Giardia lamblia. Strikingly, there is a common theme regarding the structural basis of this karyotype variability. Chromosomes are compartmentalized into conserved central domains and polymorphic chromosome ends. Since antigen-encoding genes frequently reside in telomere-proximal domains, it is tempting to speculate that the genetic flexibility of chromosome ends has been recruited as a tool in immune evasion strategies by some parasitic protozoa.

Animals↗
PubMed1999

The aspartic proteinase from the rodent parasite Plasmodium berghei as a potential model for plasmepsins from the human malaria parasite, Plasmodium falciparum.

The gene encoding an aspartic proteinase precursor (proplasmepsin) from the rodent malaria parasite Plasmodium berghei has been cloned. Recombinant P. berghei plasmepsin hydrolysed a synthetic peptide substrate and this cleavage was prevented by the general aspartic proteinase inhibitor, isovaleryl pepstatin and by Ro40-4388, a lead compound for the inhibition of plasmepsins from the human malaria parasite Plasmodium falciparum. Southern blotting detected only one proplasmepsin gene in P. berghei. Two plasmepsins have previously been reported in P. falciparum. Here, we describe two further proplasmepsin genes from this species. The suitability of P. berghei as a model for the in vivo evaluation of plasmepsin inhibitors is discussed.

Amino Acid Sequence↗
PubMed2000

Gastroallergic anisakiasis: borderline between food allergy and parasitic disease-clinical and allergologic evaluation of 20 patients with confirmed acute parasitism by Anisakis simplex.

BACKGROUND: Human subjects can be parasitized by Anisakis simplex by eating raw or undercooked fish. Gastric anisakiasis is probably the most frequent clinical entity presenting with severe epigastric pain, vomiting, and diarrhea. In gastroallergic anisakiasis hypersensitivity symptoms predominate. OBJECTIVE: We sought to describe clinical features, laboratory data, and gastroscopic findings in gastroallergic anisakiasis. METHODS: We selected 40 patients presenting to the emergency department with an acute allergic reaction, and if we suspected acute parasitism by A simplex, a fiberoptic gastroscopy was performed. In 20 patients we could detect one or more nematodes; these patients are referred to as group A. Those in whom no worm could be found are referred to as group B (n = 20). A detailed history, clinical features, gastroscopic findings, laboratory data, and skin prick test responses were compared. RESULTS: Long-time intervals of up to 26 hours between fish intake and onset of hypersensitivity symptoms were found (group A, 5.4 +/- 6.3 hours; group B, 5.3 +/- 2.6 hours). Patients in groups A and B did not differ with respect to allergic symptoms (urticaria, angioedema, erythema, bronchospasm, and anaphylaxis) or the mainly light abdominal symptoms (upper abdominal pain, nausea, vomiting, and diarrhea). No significant differences were found with respect to age, time interval between fish intake and onset of symptoms, white cell and eosinophil counts, specific IgE levels against A simplex, or total IgE levels. CONCLUSIONS: The peculiar sometimes long-time interval between fish intake and onset of allergic symptoms render the diagnosis difficult. An early gastroscopy can confirm the diagnosis and prevent complications. We suggest that gastroallergic anisakiasis be considered a distinct clinical entity in which the predominant symptoms are hypersensitivity symptoms and in which the correct diagnosis is not only important in the management of the acute reaction but also in the prevention of further allergic episodes.

Acute Disease↗
PubMed1999

Characterization of protein Ser/Thr phosphatases of the malaria parasite, Plasmodium falciparum: inhibition of the parasitic calcineurin by cyclophilin-cyclosporin complex.

Two major protein phosphatase (PP) activities were purified from cytosolic extracts of the erythrocytic stage of the malaria parasite, Plasmodium falciparum. Both enzymes were specific for phosphoserine and phosphothreonine residues with very little activity against phosphotyrosine residues. The biochemical properties of the enzymes suggested their strong similarity with eukaryotic PP2A and PP2B protein phosphatases. Both enzymes preferentially dephosphorylated the alpha subunit of phosphorylase kinase, and were resistant to inhibitor-1. The PP2A-like enzyme required Mn2+ for activity and was inhibited by nanomolar concentrations of okadaic acid (OA). The cDNA sequence of the PP2A-like enzyme was identified through a match of its predicted amino acid sequence with the N-terminal sequence of the catalytic subunit. The PP2B-like (calcineurin) enzyme was stimulated by calmodulin and Ca2+ or Ni2+, but was resistant to OA. Malarial calcineurin was strongly and specifically inhibited by cyclosporin A (CsA) only in the presence of wild type P. falciparum cyclophilin but not a mutant cyclophilin. The inhibition was noncompetitive, and provides a potential explanation for the cyclosporin-sensitivity of the parasite. There was no significant quantitative difference in the total protein Ser/Thr phosphatase activity among the ring, trophozoite, and schizont stages.

Amino Acid Sequence↗
PubMed1994

Regional versus local helminth parasite richness in British freshwater fish: saturated or unsaturated parasite communities?

The relationships between regional species richness and local species richness were examined in respect of helminth parasite communities in 32 species of freshwater fish in the British Isles. Fish were divided into 5 categories, for each of which the goodness of fit of the relationship to linear, exponential and power function models was tested. For all categories of fish combined, there was a significant, positive curvilinear relationship. Nested within this were two other patterns. For introduced fish, a linear model provided the best fit; for euryhaline and relict species it was impossible to determine the best model, but for the other categories the relationship was curvilinear and was best fitted by a power function model. The linear relationship found for introduced fish was interpreted as a temporary situation, reflecting the shortage of time for the communities to become saturated. It corresponded to the linear part of the curvilinear relationship of the other categories, which is believed to represent the fundamental form of the relationship for parasite communities. The communities reached a saturation level of richness, corresponding to the asymptote of the curve, which fell well below regional species richness. Explanations for local saturation are discussed, but neither community structure nor supply-side ecology can yet be preferred. It is concluded that local patterns in helminth community richness, in contrast to those in fish assemblages, are not significantly influenced by patterns on a larger, regional spatial scale and so regional species richness is not a key determinant of local species richness, nor does a knowledge of regional patterns improve predictability of local patterns.

Animals↗
PubMed1979

IgG1 hypergammaglobulinaemia in chronic parasitic infections in mice: magnitude of the response in mice infected with various parasites.

Mice chronically infected with 3 metazoan and 1 protozoan parasite contain in their circulation levels of IgG1 which are increased over the levels in uninfected mice by at least 10x. In the case of infection with the larval cestode, Mesocestoides corti, the serum IgG1 concentration can reach greater than 50 mg/ml and, with a half-life of less than 2 days, the number of cells engaged in IgG1 production is approximately 2 x 10(8). The IgG1 hypergammaglobulinaemia is not seen in infected hypothymic nude mice. Biosynthetic labelling studies with organ and tissue cultures established that in two of the chronic infections the organs principally involved in IgG1 synthesis were those pathologically involved or those "in line" for antigen capture: i.e. liver and spleen in the case of M. corti which is located in the liver and the peritoneal cavity, and various intestinal lymph nodes in the case of the gut-dwelling nematode, Nematospiroides dubius. This apparently exaggerated response to chronic parasitic infection is of interest simply because of the potential magnitude of the effect and the fact that it involves an Ig isotype with very poorly defined biological function.

Animals↗
PubMed2004

Two new species of Cichlidogyrus Paperna, 1960 (Monogenea, ancyrocephalidae) gill parasites on Hemichromis fasciatus (Pisces, Cichlidae) in Africa, with remarks on parasite geographical distribution.

The examination of gill parasites from Hemichromis fasciatus Peters, 1858 (Pisces, Cichlidae) in Africa revealed the presence of nine species of Monogenea, three belong to Onchobdella Paperna, 1968 and the others to Cichlidogyrus Paperna, 1960. Seven have been previously described (O. aframae Paperna, 1968; O. bopeleti Bilong Bilong & Euzet, 1995; O. voltensis Paperna, 1968; C. dageti Dossou & Birgi, 1984; C. euzeti Dossou & Birgi, 1984; C. falcifer Dossou & Birgi, 1984 and C. longicirrus Paperna, 1965); two, belonging to the latter genus, are considered as new species: C. sanseoi n. sp. and C. teugelsi n. sp. As parasitic species are not present in all the host distribution area, we think that H. fasciatus is made up of two distinct populations (or even sister species).

Africa, Western↗
PubMed2006

Leishmania histone H1 overexpression delays parasite cell-cycle progression, parasite differentiation and reduces Leishmania infectivity in vivo.

Episomal expression of Leishmania histone H1 sense mRNAs in Leishmania major promastigotes was found previously to result in overexpression of this molecule and to reduce parasite infectivity in vitro. Herein, we evaluated the in vivo infectivity of these transfectants, in BALB/c mice, and showed that it is dramatically reduced. No lesions were observed in this group of mice and this was associated with an extremely low number of parasites both in the footpad and in the draining lymph nodes. Interestingly, the transfectants-reduced infectivity was associated with a delay in their cell-cycle progression and differentiation to axenic amastigotes, assessed in vitro. Therefore, the dramatic reduction in their infectivity may be attributed to the above-mentioned phenotypic modifications. As the metazoan linker histone H1(0) homologue is known to delay cell-cycle progression in mammalian cells we investigated whether its Leishmania counterpart, which possesses homology to its C-terminal region, when expressed in mammalian cells may also affect their cell-cycle progression. It was thus shown that Leishmania histone H1 expressed in COS7 and NIH 3T3 cells, delays cell-cycle progression in these cells too. The latter strengthens the phenotype observed in Leishmania and provides evidence that critical functions of histone H1 molecules are conserved throughout evolution.

Animals↗
PubMed1984

A new malaria parasite Plasmodium (Sauramoeba) heischi in skinks (Mabuya striata) from Nairobi, with a brief discussion of the distribution of malaria parasites in the family Scincidae.

A new species of malaria parasite, Plasmodium (Sauramoeba) heischi, is described from African skinks (Mabuya striata). Eleven individuals of 90 specimens collected in Nairobi were found to be infected. The new parasite is a large species, characterized by spindle-shaped gametocytes, the female often with a subterminal nucleus. The schizonts produce up to 65 nuclei and cause great hypertrophy and distortion of the host cell. Although similar to P. (Sauramoeba) giganteum in dimensions and merozoite numbers, P. heischi is easily distinguished by gametocyte and schizont shapes.

Animals↗
PubMed1982

In vitro parasite-monocyte interactions in human leishmaniasis. Evidence for an active role of the parasite in attachment.

Leishmania are obligate intracellular parasites of mononuclear phagocytes in the mammalian host. To more clearly define features of the early events in host-parasite interaction, human monocytes were so-cultured with Leishmania tropica amastigotes in vitro. Infection of monocytes was time dependent and inhibited at 4 degrees C and in the presence of cytochalasin B. Pretreatment of amastigotes with cytochalasins prevented their attachment to normal monocytes. Untreated amastigotes attached normally but could not enter cytochalasin-pretreated monocytes. This suggests that amastigotes actively participate in attachment but require host cell participation for interiorization.

Animals↗
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↗
PubMed1964

Studies On The Parasitic Helminths Of Korea: II. Parasites Of The Rat, Rattus Norvegicus Erxl. In Seoul, With The Description Of Capillaria Hepatica(Bancroft, 1893) Travassos, (1915).

An investigation of the helminth parasites of house rat R. norvegicus Erxl. in Seoul has been carried on four years. A total of 325 rat was examined. Ten species of helminths were considered, of which 4 species were recored for the first time from Korea. The adult worm of Capillaria hepatica, the most common parasite of house rats in Seoul, was observed experimentally, and provided a more complete description of this worm.

Journal Article↗