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PubMed1992

[The prevalence of intestinal parasites in primary school students in Trabzon and the importance of education of parasite patients].

Hundred and forty stool samples obtained from fourth classes (10 years of age) of the primary school students were examined for intestinal parasites. In addition, effect of education and variety of education on parasitic diseases were investigated. Of the 140 students 65% were found to be positive for intestinal parasites. Ascaris lumbricoides 15.7%, Trichuris trichiura 22.85%, Giardia intestinalis 7.14%, Ascaris lumbricoides + Trichuris trichiura 15.7%, Giardia intestinalis + Trichuris trichiura 3.57% were found. The infested students were treated with antiparasitic drugs, and were educated for parasitic diseases. 50% of the student were given brochure, the others were given brochure and verbal education. After 1.5 month control stool samples were taken. In both groups infestation rate was 27.14%. Ration was 18.57% in only brochure given group, and 8.57% in brochure and verbal education given group. The difference between two group was meaningful (X2 = 3.89 P less than 0.05).

Ascariasis↗

PubMed1978

[Parasites of Salmo trutta L. from the Tirino River. II. Host-parasite interactions of helminth species].

The hundred and sixteen brown trout (Salmo trutta L.) which were examined for helminth parasites were captured in the River Tirino, (L'Acquila - Italy). Six parasite species (Phyllodistomum simile, Crowcrocaecum testiobliquum, Crepidostomum metoecus, Cyathocephalus truncatus, Truttaedacnitis truttae and Dentitruncus truttae) were recovered. Ecological studies on each helminth species recovered have been carried out analysing the following aspects; the preference of each parasite species for certain microhabitats in the host; the incidence and intensity of each parasitic infection according to sex, age and season.

Age Factors↗

PubMed1986

Bovine cytotoxic T-cell clones specific for cells infected with the protozoan parasite Theileria parva: parasite strain specificity and class I major histocompatibility complex restriction.

We present information on the specificity of three bovine cytotoxic T-cell clones reactive with lymphoblasts infected with the protozoan parasite Theileria parva. The clones were derived from peripheral blood mononuclear cells of an animal immunized with T. parva (Muguga stock), after five stimulations in vitro with an autologous parasitized cell line. The three clones belonged to the BoT8+ subset of T cells, which is similar to the human CD8+ T-cell subset. On the basis of analysis on a panel of infected target cells originating from cattle of different major histocompatibility complex (MHC) phenotypes, killing by all three clones was found to be restricted to targets bearing the class I MHC specificity KN104, which is defined by alloantiserum KNA104 and monoclonal antibody IL-A4. This class I MHC restriction was confirmed by blocking of target cell lysis with these antibodies and monoclonal antibody w6/32, which reacts with a nonpolymorphic determinant on bovine class I MHC molecules. The three clones were parasite strain specific, in that they did not kill cells of the appropriate MHC type infected with T. parva (Marikebuni stock). These findings, taken together with previous observations that immunization of cattle with T. parva (Muguga) does not provide protection against challenge with T. parva (Marikebuni), suggest that the cytotoxic T cells recognize a cell surface antigen that may be important in induction of immunity to the parasite.

Animals↗

PubMed1992

Intravascular filarial parasites inhibit platelet aggregation. Role of parasite-derived prostanoids.

The nematode parasites that cause human lymphatic filariasis survive for long periods in their vascular habitats despite continual exposure to host cells. Platelets do not adhere to blood-borne microfilariae, and thrombo-occlusive phenomena are not observed in patients with circulating microfilariae. We studied the ability of microfilariae to inhibit human platelet aggregation in vitro. Brugia malayi microfilariae incubated with human platelets caused dose-dependent inhibition of agonist-induced platelet aggregation, thromboxane generation, and serotonin release. As few as one microfilaria per 10(4) platelets completely inhibited aggregation of platelets induced by thrombin, collagen, arachidonic acid, or ionophore A23187. Microfilariae also inhibited aggregation of platelets in platelet-rich plasma stimulated by ADP, compound U46619, or platelet-activating factor. The inhibition required intimate proximity but not direct contact between parasites and platelets, and was mediated by parasite-derived soluble factors of low (less than 1,000 Mr) molecular weight that were labile in aqueous media and caused an elevation of platelet cAMP. Prior treatment of microfilariae with pharmacologic inhibitors of cyclooxygenase decreased both parasite release of prostacyclin and PGE2 and microfilarial inhibition of platelet aggregation. These results indicate that microfilariae inhibit platelet aggregation, via mechanisms that may include the elaboration of anti-aggregatory eicosanoids.

Animals↗

PubMed1990

[Characteristics of helminthic parasitism in cattle in Ituri (Haut-Zaire). II. Parasitic associations].

A total of 781 cattle was examined at the Bunia slaughterhouse (Ituri) from August 1986 to December 1987 to study the following parasitic associations: Fasciola sp., Schistosoma sp., paramphistomes and Fasciola sp., Haemonchus sp., Oesophagostomum sp. Prevalences were high for each parasite: 96.5% for paramphistomes, 58.1% for Schistosoma sp., 58.7 to 61.9% for Fasciola sp., 90.5% for Haemonchus sp. and 75.5% for Oesophagostomum sp. Regarding the association with trematodes, 41.3% of the 516 examined animals were simultaneously positive for the three helminths and there was a significant relationship between the infection with Fasciola sp. and Schistosoma sp. Regarding the association with Fasciola sp., Haemonchus sp. and Oesophagostomum sp., a total of 44.5% of the 265 examined animals harboured the three parasites together, but infections seemed not to be linked. Moreover, the corresponding gross lesions were moderate suggesting a low level of the parasitic burdens.

Animals↗

PubMed1991

Longitudinal study of young children in Kenya: intestinal parasitic infection with special reference to Giardia lamblia, its prevalence, incidence and duration, and its association with diarrhoea and with other parasites.

84 young children from a rural community, Nderu, in Kenya, were each followed for up to 10 months, from January to November 1987. Their ages ranged from 10 to 28 months over the period of study. Stools were obtained once a week, as were reports from the mothers about presence of abdominal complaints, including diarrhoea. A total of 2258 stools and 1873 reports were collected. 9 parasites were commonly encountered of which Giardia lamblia was the most frequent at 44.7%. The overall estimated number of new Giardia episodes per year per child was 2.77 +/- 2.22 SD and the mean estimated duration of infection was 75.25 +/- 73.84 SD days per child. The mean proportion of positive visits per child was 0.42 +/- 0.25 SD. Giardia trophozoites, Trichomonas hominis, Chilomastix mesnili, Entamoeba histolytica, Blastocystis hominis and Hymenolepis nana were all significantly associated with unformed stools and reports of diarrhoea. There was a significant probability of finding Giardia in stool within +/- 2 weeks of a report of diarrhoea. Poly-parasitism was common and several paired associations were significantly positive, particularly between species of amoebae. Quantity of Giardia in stool (expressed as a 0 to 5+ score) was suppressed both by type and number of other parasites present.

Age Factors↗

PubMed1991

A simple model of host-parasite evolutionary relationships. Parasitism: compromise or conflict?

The evolutionary biology of host-parasite relationships are considered here using a simple game-theory model in which hosts play against parasite and vice versa. In this model, the players can choose between two strategies (aggressive or not aggressive) and the utility of the game is envisaged in terms of fitness and selective costs. The game solutions suggest that the two types of confrontation are encountered in symbiotic relationships and thus constitute two Evolutionary Stable Strategies (ESS). These observations lead us to discuss: (i) the status of different kinds of symbiotic relationships (i.e. parasitoidism; parasitism, commensalism and mutualism) related to selective costs and (ii) the position of coevolution in this game theory context.

Animals↗

PubMed1985

In vitro parasite-monocyte interactions in human leishmaniasis: possible role of fibronectin in parasite attachment.

Leishmania spp. must attach to mononuclear phagocyte surfaces before entering this host cell. We investigated the potential role of fibronectin in facilitating parasite attachment. Human plasma fibronectin bound to axenically cultured promastigotes, and promastigotes and amastigotes preferentially bound to fibronectin-coated cover slips. Promastigotes grown in the absence of fibronectin were strikingly deficient in their ability to attach to human monocytes compared with promastigotes grown in the presence of fibronectin. Rabbit anti-human plasma fibronectin antiserum decreased promastigote and amastigote attachment to monocytes. Immunoglobulin G F(ab')2 and Fab fragments also reduced the ability of amastigotes to bind to monocytes. Antiserum pretreatment of amastigotes followed by washing resulted in reduced parasite binding, whereas antibody pretreatment of monocytes did not. Addition of exogenous fibronectin did not enhance parasite attachment to monocytes. These findings suggest that Leishmania spp. can bind fibronectin and may utilize this glycoprotein to facilitate attachment to the mononuclear phagocytes that they infect.

Animals↗

PubMed1992

Human ecology and parasitic infections. 1. The effect of occupation on the prevalence of parasitic infections in Calabar, Nigeria.

One thousand six hundred people belonging to three different occupational groups were randomly selected. Blood, urine and stool specimens were collected from them and processed for the detection of any parasitic infections. The results show 28.5% infection rate with one or more species of intestinal parasites; 50.7% in the school children, 17.3% among the farmers, and 12% among the soldiers. Results of blood examination showed 5.3%, 8.0% and 2.0% infection rates for P. falciparum in the school pupils, farmers and soldiers respectively, while 31.3% of the three groups were infected with the microfilaria of Dipetalonema perstans, and Loa loa. These were found in 60.7% of the farmers and none at all in the other two groups. Urine examination yielded no positive cases of urinary schistosomiasis and only one case of Trichomonas vaginalis. These results reflect the endemicity of the respective parasites, the degree of their sanitary awareness and their exposure frequencies to the pathogens as a result of their daily activities.

Animals↗

PubMed1990

[Parasite prevalence in schools with different socioeconomic status and evaluation of methods for diagnosing intestinal parasitic diseases].

In this study; the parasite prevalence of schools with different socio-economical status and three methods for diagnosing intestinal parasitosis were evaluated. Children from two primary schools and one junior high school with different socio-economical status participated in the study. The three method used for diagnosing parasitosis in this study were direct wet mounts, concentrated saline flotation technique, and zinc sulfate centrifugal flotation method. Parasitosis was found in 69 fecal samples (18%). The distribution of the parasites found were Hymenolepis nana (29%), Ascaris lumbricoides (26%), Enterobius vermicularis (23%), Trichirus trichiura (18%), taenia saginata (4%). The parasite prevalence in schools with low and high socioeconomical status differed significantly (27% vs. 5% respectively). Combined methods were superior to single methods. The combined method of direct wet mounts and zinc sulfate centrifugal flotation was the most sensitive method (diagnosis rate 90%). But we think that the combined method of direct wet mounts and concentrated saline flotation technique is a simpler method with almost equal results (86%).

Adolescent↗

PubMed1979

Free-flow electrophoresis for the separation of malaria infected and uninfected mouse erythrocytes and for the isolation of free parasites (Plasmodium vinckei): a new rapid technique for the liberation of malaria parasites from their host cells.

After aggregation of erythrocytes from malaria infected mice, the parasites (Plasmodium vinckei) could be set free using gentle mechanical forces. The mixture of freed parasites, infected and non-infected erythrocytes, and membraneous material was separated by free-flow electrophoresis. The free parasites produced were very pure and infectious. Morphological and enzymatic data on the separated fractions are presented. Free-flow electrophoresis also allowed the separation of infected and uninfected erythrocytes.

Animals↗

PubMed1990

Parasite-induced processes for adenosine permeation in mouse erythrocytes infected with the malarial parasite Plasmodium yoelii.

In mouse erythrocytes harbouring the malarial parasite Plasmodium yoelii, three processes contributed to inward fluxes of adenosine, one of which is attributed to the native nucleoside transporter, because of the inhibitory effects of nitrobenzylthioinosine (NBMPR). New (parasite-induced) permeation processes of low NBMPR-sensitivity were (i) saturable fluxes with preference for the D enantiomer (D-Ado) and (ii) apparently unsaturable fluxes that proceeded by a channel-like route without enantiomeric selectivity. Parasite-induced fluxes of L- and D-Ado were similarly inhibited by furosemide [IC50 (concn. causing half-maximal inhibition) 15-17 microM], whereas D-Ado fluxes in uninfected erythrocytes were 10-fold less sensitive.

Adenosine↗

PubMed1986

Cloning and comparison of repeated DNA sequences from the human filarial parasite Brugia malayi and the animal parasite Brugia pahangi.

A 320-base-pair repeated sequence was observed when DNA samples from the filarial parasites Brugia malayi and Brugia pahangi were digested with the restriction endonuclease Hha I. A 640-base-pair dimer of the repeated sequence from B. malayi was inserted into the plasmid pBR322. When dot hybridization was used, the copy number of the repeat in B. malayi was found to be about 30,000. The 320-base-pair Hha I repeated sequences are arranged in direct tandem arrays and comprise about 12% of the genome. B. pahangi has a related repeated sequence that cross-hybridizes with the cloned B. malayi Hha I repeat. Dot hybridization with the cloned repeat shows that the sequence is present in B. malayi and in B. pahangi but not in four other species of filarial parasites. The cloned repeated DNA sequence is an extremely sensitive probe for detection of Brugia in blood samples. Hybridization with the cloned repeat permits the detection of DNA isolated from a single parasite in an aliquot of blood from animals infected with B. malayi. There are differences in the restriction sites present in the repeated sequences that can be used to differentiate between the two Brugia species. The B. malayi repeated DNA sequence is cleaved by Alu I and Rsa I but the B. pahangi sequence is not. A comparison of repeated sequences between the two species by DNA sequence analysis indicates that some regions of individual repeats are over 95% homologous, while other short regions are only 60-65% homologous. These differences in DNA sequence will allow the construction of species-specific hybridization probes.

Animals↗

PubMed1979

Biochemistry of intraerythrocytic parasites. I. Identification of enzymes of parasite origin by starch-gel electrophoresis.

Enzymes of parasite origin were identified by starch-gel electrophoresis. The species of parasite studied were Plasmodium berghei, Plasmodium yoelii nigeriensis, Babesia rodhaini and Anthemosoma garnhami. Lactate dehydrogenase, glucose phosphate isomerase and (NADP) glutamate dehydrogenase were detected in all species; phosphogluconate dehydrogenase was detected in both Plasmodium species but malate dehydrogenase only in P. y. nigeriensis. Glucose-6-phosphate dehydrogenase, alanine aminotransferase and aspartate aminotransferase were not detected in any parasite.

Alanine Transaminase↗

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↗