PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “parasitism”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1991

The parasites of the Polynesian rat: biogeography and origins of the New Zealand parasite fauna.

Unique aspects of the prehistory and current distribution of the Polynesian rat (Rattus exulans Peale) have been applied to the problem of determining the biogeographical origin of its parasites as found on 'exulans only' islands of New Zealand. The database consists of collated records of both endo- and ectoparasites reported from throughout this rat's geographical range. The analytical method is based on the concepts of Sprent (1969. Immunity to Parasitic Animals, pp. 14-17) and includes the formulation and testing of two hypotheses. A total of six 'heirloom' species is identified, and a further seven are classified as 'old souvenirs'. Contrary to prediction, 11 species are considered to be 'new souvenirs', acquired from other rodent species now present in New Zealand.

Animals↗
PubMed1989

Comparative morphology of human and animal malaria parasites. I. Host-parasite interface.

Human and animal malaria parasites (Plasmodium falciparum, P. malariae, P. vivax, P. berghei, P. gallinaceum) were studied using special fixation and standardized methods, with special attention to their effects on host cells. Morphological alterations induced by the parasites in infected erythrocytes included knobs, invaginations, and caveola-vesicle complexes on the surface of the host cell and clefts, microvesicles, and small vesicles in the cytoplasm of the infected erythrocytes. For P. malariae, the ultrastructural study revealed invaginations with associated microvesicles, but knobs did not occur on the surface of infected erythrocytes. The development of invaginations and microvesicles in P. malariae-infected erythrocytes corresponded to the morphological alterations induced by P. vivax. A new hypothesis concerning the origin of Schüffner's dots is discussed.

Animals↗
PubMed1989

Survey of internal parasites in Western Australian pig herds. 2. Relationship to anthelmintic usage and parasite control practices.

The housing, management and internal parasite control practices used in piggeries in Western Australia was surveyed by interviewing the owner/manager of 100 randomly selected piggeries. At the time of the interview 20 faecal samples were collected from pigs and examined for evidence of internal parasites. Most herds (80%) in which anthelmintics were used, had evidence of nematode infection. Some pig producers were using an anthelmintic that was ineffective against nematode species present while some herds had nematodes that should have been controlled by the anthelmintic being used. Prevalence of nematode infection was higher in pigs run in paddocks than in pigs housed intensively. Washing sows prior to farrowing was associated with a lower prevalence of nematode infection. The findings suggested that pig producers should ensure that the anthelmintic used is effective against the nematodes present in their pigs. It was concluded that administering anthelmintics as a single dose in the feed may not be the most effective method of deworming pigs.

Animal Husbandry↗
PubMed1990

Observations on parasitic gastroenteritis and parasitic bronchitis in calves over two grazing seasons.

Two outbreaks of parasitic gastroenteritis were observed in a group of 10 first-season grazing calves, one in mid-July and one in mid-September. In both cases emergency anthelmintic treatment was needed to prevent further damage. Severe clinical signs were observed together with high faecal egg counts and high serum pepsinogen and gastrin concentrations. Low total protein and albumin concentrations were also observed, especially during the second outbreak. The ostertagia antibody levels followed a similar pattern to the serum pepsinogen and gastrin concentrations. At the end of the housing period a mild type II ostertagiasis was observed. In the second grazing season the heifers did not show any signs of parasitic gastroenteritis, but there was a serious outbreak of husk which required treatment.

Animals↗
PubMed1978

Studies on the host-parasite relationship in Schistosoma mansoni-infected mice: the immunological dependence of parasite egg excretion.

CBA mice deprived of their T cells by means of thymectomy and anti-thymocyte serum and subsequently infected with Schistosoma mansoni were found to have substantially fewer parasite eggs in their faeces than similarly infected immunologically-intact control animals. The number of parasite eggs deposited in the tissues of T-cell deprived mice was by comparison only marginally lower than in control mice. Administration of serum obtained from normal mice with chronic S. mansoni infections partially restored the egg excretion rate in infected deprived mice, and also resulted in an increased number of eggs being deposited in the liver and intestine of these animals.

Animals↗
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↗
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↗
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↗
PubMedDate not supplied

Parasitic Protozoa of the blood of rodents. V. Plasmodium vinckei brucechwatti subsp. nov. A malaria parasite of the thicket rat, Thamnomys rutilans, in Nigeria.

A description is given of the blood stages of a new subspecies of Plasmodium vinckei in the blood of naturally infected thicket rats (Thamnomys rutilans) from Nigeria and experimentally infected mice. Sporogony was obtained at 25 degrees C in Anopheles stephensi A. quadrimaculatus and A.l. atroparvus, but sporozoites in the salivary glands of the mosquitoes were never infective. The new parasite is differentiated from 7 other species of malaria parasites of African rodents principally on the morphology of the erythrocytic stages. It is designated as a subspecies of P. vinckei (P.v. brucechwatti subsp. nov.) because of the (i) zoogeography, (ii) morphology of sporogonic stages and (iii) forms isoenzymes of blood stages.

Animals↗
PubMed1986

Parasites of domestic and wild animals in South Africa. XXI. Arthropod parasites of vaal ribbok, bontebok and scrub hares in the western Cape Province.

Vaal ribbok (Pelea capreolus), bontebok (Damaliscus dorcas dorcas) and scrub hares (Lepus saxatilis) were slaughtered in the Bontebok National Park at regular intervals and examined for arthropod parasites. Twelve species of ixodid ticks were recovered; the antelope each harboured 9 species and the hares 11. Rhipicephalus nitens was the most prevalent and most abundant tick. The vaal ribbok also harboured large numbers of Ixodes pilosus and the bontebok fairly large numbers of Rhipicephalus glabroscutatum. The vaal ribbok were infested with 2 lice species and the larvae of 3 oestrid fly species. The bontebok harboured 2 lice species and the larvae of 2 oestrid flies, and the scrub hares were infested with a louse species and a flea species. The host preference and seasonal abundance of some of the parasites were determined.

Animals↗
PubMed1978

[Parasites of Salmo trutta L. from the Titino River. Part III. Histological observations of parasites of the intestinal tract].

During researches on helminth parasites of Salmo trutta L. from the River Tirino (L'Aquila - Italy) histological studies of the intestinal tract of brown trout infected by the following species: Crowcrocaecum testiobliquum (Wisnewski, 1932) Skrjabin e Koval, 1956; Cyathocephalus truncatus (Pallas, 1781);o Truttaedacnitis truttae (Fabricius, 1794) Petter, 1974 and Dentitruncus truttae Sinzar, 1955 have been carried out. The attachment of the single species and the histological changes in the host gut due to parasite species have been described.

Animals↗
PubMed1986

Bioecology of the parasites of high altitude homeothermic host-parasite systems. II. Infections by strobilocerci of Hydatigera balaniceps (Hall), H. laticollis (Rudolphi) and H. parva (Baer) in relation to sex, size and weight of Indian house rat.

The influence of sex, size and weight of the Indian house rat (Rattus rattus) on concurrent liver infections with Hydatigera balaniceps (Hall), H. laticollis (Rudolphi) and H. parva (Baer) has been discussed. A significant inverse relationship was recorded between cestode infection and rat size. Parasitization index and mean worm burden-host weight ratio decreased with increase in rodent weight.

Altitude↗
PubMed1986

Phosphorylcholine bearing components of some helminthic parasites: localization to parasite lipoproteins.

Extracts of various helminthic parasites were studied to determine the molecular carrier of the hapten phosphorylcholine (Pc). Physicochemical studies showed that the carrier was heterogeneous with regard to apparent molecular weight (70,000-greater than 10(6) daltons). Ultracentrifugal analysis of Ascaris suum and Nippostrongylus brasiliensis showed that Pc was associated with low (LDL), high (HDL) and a heterogeneous group of very high density (VHDL) lipoproteins. The majority of Pc was found in the most dense VHDL (d greater than 1.25 g ml-1). The apparent molecular weight and particle diameter of A. suum HDL was 751,000 daltons and 16.2 nm, respectively. The apparent molecular weights and particle diameters of A. suum VHDL ranged from 469,000 to 677,000 daltons and 13.6 to 15.5 nm, respectively. The electrophoretic mobilities of A. suum LDL and HDL were beta and gamma, respectively. A suum VHDL was electrophoretically heterogeneous. It is probable that Pc is associated with the phospholipid phosphatidylcholine.

Animals↗
PubMed1977

Physiology of host parasite relationship: effects on serum alkaline phosphatase levels of fish hosts parasitized by trypanosomes.

Serum alkaline phosphatase levels of five species of fresh water fish hosts were altered by trypanosome parasites. The loss in enzymatic activity ranged from 3.91% to 69.91% in the five species of infected fishes as compared to normal level in the healthy hosts. The maximal reduction in the enzymatic activity caused by trypanosomes was observed in the herbivore carp fish Cirrhina mrigala and the minimal loss in the fresh water shark Wallago attu.

Alkaline Phosphatase↗
PubMed1989

Bacteriophage introns: parasites within parasites?

Several bacteriophage introns carry the information necessary to perform a complex series of RNA as well as DNA rearrangements. The RNA splicing reactions allow expression of the intron-containing genes, whereas recombination at the DNA level results in the mobility and invasive potential of the introns. The RNA and DNA transactions are temporally regulated to permit timely splicing early in infection, and expression of intron-encoded DNA endonucleases involved in mobility at late times. This is achieved through efficient use of the viral regulatory machinery, ensuring the perpetuation of the 'parasitic' introns.

Animals↗
PubMed1991

Epitopes of the human malaria parasite P. falciparum carried on the surface of HBsAg particles elicit an immune response against the parasite.

The development of recombinant subunit vaccines against pathogenic organisms requires not only the identification of epitopes eliciting a protective immune response but also suitable carriers with adjuvant function. B- and T-cell epitopes of the malaria vaccine candidate gp190 were selected on the basis of a systematic search along the gp190 molecule and by computer prediction based on the amino acid sequence. Using some of the epitopes identified, we have redesigned the surface of the hepatitis B surface antigen lipoprotein particles by replacing the major antigenic determinants with malaria-specific sequences of up to 61 amino acids in length. Upon expression via vaccinia virus the hybrid particles elicit an anti-gp190 immune response in animals. Monoclonal antibodies derived from such infections recognize the native parasite.

Amino Acid Sequence↗