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PubMedDate not supplied

Intestinal parasites and the environment: frequency of intestinal parasites in children of Neuquén, Patagonia, Argentina.

The frequency of intestinal parasites (IP) in 69 children between 2 and 14 years of age was studied within the city of Neuquén, Patagonia, Argentina in relation to socioeconomic, cultural and environmental conditions. Soil type was determined and contamination with IP was investigated in 75 soil samples. Frequency of IP in children was 50.7%. Blastocystis hominis was the most frequent species (24.6%). Simultaneous infection with 2 to 4 species was found in 47,5% of the infected children. Statistical association was found between parasitic infection and family hygienic level (p < 0.001). Socioeconomic level was defined as lower middle class, however, infrastructure and public services were adequate. The climate is continental semiarid and the soil is sandy with a low organic matter level. Intestinal protozoan organisms were found in 33.3% of soil samples and Sarcocystis sp. was the most frequent species (14.6%). The parasites present in soil are related to the environmental conditions that allow their viability and development. Socioeconomic and cultural factors are important for the appearance and spread of IP in communities where sanitary conditions and infrastructure are adequate.

Adolescent↗
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↗
PubMed1994

[Report on the first nationwide survey of the distribution of human parasites in China. 1. Regional distribution of parasite species].

A nationwide (Taiwan Province not included) survey of the distribution of human parasites in China during 1988-1992 was conducted under the auspices of the Ministry of Public Health, with stratified masses randomly sampling. A total of 2,848 pilot sites in 726 counties with a population of 1,477,742 were surveyed, according to unified standard, unified diagnostic method and control quality. The overall infection rate of parasites was 62. 632%. Among them, the infection rate was over 50% in 17 provinces/autonomous regions/municipalities (P/A/M), over 80% in Hainan, Guangxi, Sichuan, Fujian, Zhejiang and Guizhou, being highest in Hainan (94. 735%). Altogether 56 species were detected. Centrocestus formosanus is reported for the first time at home, Echinochasmus liliputanus and Echinostoma angustitestis are reported for the first time at home and abroad. Echinochasmus fujianensis is a new species. E. histolytica, G. lamblia, A. lumbricoides, whipworm and pinworm were distributed nationwide, while Cysticercus (27 P/A/M), Taenia (27), hookworm (26), Balantidium coli (22), Clonorchis sinensis (22), Paragonimus westermani (21), H. diminuta (21), Echinococcus (18), H. nana (17), Fasciolopsis buski (16), T. spiralis (12) were distributed non-nationwide. A preliminary suggestion on intervention of the common and/or most detrimental parasitic diseases was submitted, including hydatidosis, taeniasis, cysticercosis, clonorchiasis, paragonimiasis, trichinellosis, hookworm disease, ascariasis, trichuriasis and enterobiasis.

Animals↗
PubMed1998

Parasite dose determines the Th1/Th2 nature of the response to Leishmania major independently of infection route and strain of host or parasite.

Leishmania major causes cutaneous leishmaniasis in mice and man. Infection of mice with relatively low or high numbers of parasites leads respectively to parasite containment, associated with a Th1, cell-mediated response, or progressive disease, associated with a Th2, antibody response in all circumstances studied. These include different parasite strains, different routes of infection, and different hosts previously classified as susceptible, resistant or of intermediate susceptibility. This dose dependency appears to reflect a general rule. We argue that this rule may allow the design of a vaccination strategy that is effective among a genetically diverse population, and that it imposes severe constraints upon proposals for the nature of the "decision criterion" determining whether antigen induces a Th1 or Th2 response.

Animals↗
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↗
PubMed2006

Copepods and larvae of nematodes parasitizing (correction of parasiting) the white mullet Mugil curema (Valenciennes, 1836): indicators of anthropogenic impacts in tropical coastal lagoons?

The relationship between parasites and environmental stress were studied in two tropical coastal lagoons of Northwest Mexico: Urias estuary (highly polluted) and Teacapan estuary (slightly polluted). Metazoan parasites were examined in 292 white mullet (Mugil curema) specimens collected bimonthly during a year from both systems. Haliotrema mugilinus, Metamicrocotyla macracantha, Ergasilus sp., Caligus sp., Holobomolochus sp., and Lernaeopodidae were found in gills, while Contracaecum sp. larvae III was found liver, hepatic portal vein and kidneys. Ecological indices were influenced by the slightly higher number of parasitic species in Urias compared to Teacapan, as well as the clear dominance of two species: Ergasilus sp. and Contracaecum sp. in both systems. In fact, Ergasilus sp. showed considerably higher abundance in Urias, possibly indicating that its success was a result of adverse conditions affecting the host, while Contracaecum sp showed higher abundances in Teacapan, suggesting that the environmental conditions occurring in Urias could have produced negative impacts on the nematode's infective potential.

Animals↗
PubMed1998

Biodiversity of parasites in a freshwater environment with respect to pollution: metazoan parasites of chub (Leuciscus cephalus L.) as a model for statistical evaluation.

This paper represents an attempt to evaluate the environmental indicative potential of the biodiversity of monogenean parasites using hierarchically structured species-abundance data. A logical set of statistical methods integrating standard diversity indices, a novel approach to quantitative analysis of cumulative species-abundance curves and species-abundance models was applied for this purpose. Applicability of biodiversity measures was demonstrated using experimental data from a 1-year study on the ecology of metazoan parasites of chub (Leuciscus cephalus) in one polluted and one control site in the Morava river, Czech Republic. Analyses at the component community level revealed a significant decrease in the number of parasite species with a more equal distribution of their abundances in the polluted site compared with the control site. In order to reach a better understanding of the changes, diversity of Monogenea as a dominant part of the community was further examined within categories of species created according to: (1) specificity of infection (specialists and generalists), (2) monogenean genera (Dactylogyrus, Gyrodactylus and Paradiplozoon) and (3) inhabited guilds (skin + fins, gills). Assemblages of specialists in the polluted site exhibited a significantly reduced species richness and unequal distribution of abundances. The opposite pattern was observed in the case of generalists. The influence of pollution was also reflected by the distribution of species abundances within communities of Dactylogyrus and Paradiplozoon, while no significant shift was identified in the genus Gyrodactylus.

Animals↗
PubMed2000

EST sequencing of the parasitic nematode Haemonchus contortus suggests a shift in gene expression during transition to the parasitic stages.

Expressed sequence tags from the parasitic nematode Haemonchus contortus were generated in order to identify anchor loci for comparative mapping between nematode genomes and candidate targets for future control measures. In total, 370 SL1 trans-spliced cDNAs from different developmental stages representing 195 different genes were partially sequenced. From these expressed sequence tags 50% were similar to genes with a known or predicted function and 19% were similar to nematode sequences with no ascribed function. From the first, free-living L1 and L3 stages relatively many cDNAs matched to housekeeping genes, and 11% (L1) or 23% (L3) of the encoded proteins were predicted to contain signal peptides. In contrast, no function could be ascribed to most of the cDNAs from the early L5 and adult parasitic stages, but for 30% (L5) or 55% (adult) of the encoded proteins a signal sequence was predicted. This limited analysis suggests that during the transition from the free-living to parasitic stages gene expression shifts towards the synthesis of less conserved extracellular proteins. These proteins offer the best perspectives for vaccine development and the development of anthelmintic drugs. In contrast, cDNAs from the first larval stages may be most suitable for comparative mapping with the free-living nematode Caenorhabditis elegans.

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↗
PubMed2001

Quinone oxidoreductase message levels are differentially regulated in parasitic and non-parasitic plants exposed to allelopathic quinones.

Allelopathic chemicals released by plants into the rhizosphere have effects on neighboring plants ranging from phytoxicity to inducing organogenesis. The allelopathic activity of naturally occurring quinones and phenols is primarily a function of reactive radicals generated during redox cycling between quinone and hydroquinone states. We isolated cDNAs encoding two distinct quinone oxidoreductases from roots of the parasitic plant Triphysaria treated with the allelopathic quinone 2,6-dimethoxybenzoquinone (DMBQ). TvQR1 is a member of the zeta-crystallin quinone oxidoreductase family that catalyzes one-electron quinone reductions, generating free radical semiquinones. TvQR2 belongs to a family of detoxifying quinone oxidoreductases that catalyze bivalent redox reactions which avoid the radical intermediate. TvQR1 and TvQR2 message levels are rapidly upregulated in Triphysaria roots as a primary response to treatment with various allelopathic quinones. Inhibition of quinone oxidoreductase enzymatic activity with dicumarol prior to quinone treatment resulted in increased transcript levels. While TvQR2 homologs were upregulated by DMBQ in roots of all plants examined, TvQR1 homologs were upregulated only in roots of parasitic plants. Phylogenetic trees constructed of TvQR1 and TvQR2 protein homologs in Archea, Eubacteria and Eukaryotes indicated that both gene families are ancient, yet the families have dissimilar evolutionary histories in angiosperms. We hypothesize that TvQR2-like proteins function to detoxify allelopathic quinones in the rhizosphere, while TvQR1 has specific functions associated with haustorium development in parasitic plants.

Alleles↗
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↗
PubMed1995

Verapamil reversal of chloroquine resistance in the malaria parasite Plasmodium falciparum is specific for resistant parasites and independent of the weak base effect.

Verapamil increases the net uptake and cytotoxicity of structurally diverse hydrophobic molecules in many multidrug-resistant mammalian cell lines. This compound has also been reported to reverse chloroquine resistance in the human malaria parasite Plasmodium falciparum (Martin, S.K., Oduola, A.M.J., and Milhous, W.K. (1987) Science 235, 899-901). Although the mechanism of this reversal is unknown, it apparently involves an increase in the amount of chloroquine present in erythrocytes infected with the resistant parasites. Chloroquine is a diprotic weak base that accumulates in acidic organelles as a function of the pH gradient present between the organelle and the external medium. By changing the external medium pH, this property of chloroquine was used to alter the cytotoxicity phenotype of genetically chloroquine-sensitive and -resistant trophozoites. Verapamil was also found to be toxic for malaria trophozoites, although this toxicity was independent of external pH and consistently about 3-4-fold higher against resistant strains. When verapamil was tested for its effects on chloroquine cytotoxicity under conditions of phenotypic reversal, it was still found to exert only a measurable effect on the genetically resistant trophozoites. In short time incubations, verapamil was found to increase net chloroquine accumulation in erythrocytes infected with both chloroquine-sensitive and -resistant organisms, but only to affect the chloroquine susceptibility of the latter. Analysis of our data demonstrates that verapamil works independently of the overall pH gradient concentrating chloroquine into a trophozoite's lysosome. Instead, we propose that it inhibits the activity of a membrane ion channel indirectly responsible for determining chloroquine transit within the parasite's cytoplasm.

Animals↗
PubMed1985

Monoclonal antibodies produced against sporozoites of the human parasite Plasmodium malariae abolish infectivity of sporozoites of the simian parasite Plasmodium brasilianum.

We have used a sporozoite neutralization assay to define the biological relevance of the cross-reactivity of two monoclonal antibodies, raised against sporozoites of the human parasite Plasmodium malariae (Uganda 1/CDC), with sporozoites of the simian parasite Plasmodium brasilianum (Colombian). In vitro incubation of each of these two monoclonal antibodies with sporozoites of P. brasilianum totally abolished the infectivity of these parasites for Saimiri sciureus. Using Western blot analysis and one of the P. malariae monoclonal antibodies, we identified two sporozoite proteins characteristic of the Colombian isolate of P. brasilianum with apparent molecular weights of 56,000 and 66,000. The same monoclonal antibody identified two proteins in an extract of the Peruvian isolate of P. brasilianum with apparent molecular weights of 59,000 and 69,000.

Animals↗
PubMed1980

Parasite-reactive serum IgE antibodies in African populations. Relation to intestinal parasite load.

Serum IgE levels and IgE antibodies against four intestinal parasites, and the presence and abundance of parasites in stool samples were investigated in 161 Rwanda natives. Most of the IgE turn out to be helminth-reacting antibodies. The stimulation and production of these antibodies are much different from those of anti-amoeba antibodies in their relation to the specific intestinal parasite load; helminth infestations seem to play a major role in the development of anti-amoeba antibodies as well.

Ascaris↗
PubMed1987

Parasite-specific anergy in human filariasis. Insights after analysis of parasite antigen-driven lymphokine production.

The antigen-specific immune unresponsiveness seen in bancroftian filariasis was studied by examining lymphokine production in peripheral blood mononuclear cells (PBMC) or PBMC subpopulations from 10 patients with asymptomatic microfilaremia, 13 patients with elephantiasis and 6 normal North Americans. In each group of patients, the kinetics of the lymphokine response and the response to mitogens and nonparasite antigens did not differ significantly. In marked contrast, when antigen-induced lymphokine production was examined, most patients with microfilaremia were unable to produce either interleukin 2 (IL-2) or gamma-interferon (i.e., were nonresponders), and the few who could (hyporesponders, generally with quite low microfilaremia levels) did so at levels significantly less than those of patients with elephantiasis, all of whom showed strong responses to parasite antigen. Removal of neither adherent cells or T8+ cells affected the parasite-specific anergy seen in those with microfilaremia, suggesting a state of T cell tolerance to the parasite in patients with this most common clinical manifestation of bancroftian filariasis.

Adult↗
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↗
PubMedDate not supplied

[Taxonomic diversity of parasites from agnathans and fishes in the Volga basin. II. Parasitic Coelenterata and Monogenea].

A checklist of the Monogeneans and Coelenterates parasitizing fishes in the Volga River basin is given. The list of hosts with the data on their occurrence in different areas of the Volga River basin is provided for each parasite species. The data on the parasites from 46 fish species are presented. The checklist includes 139 species and 6 taxa of subspecific rank. 9 species (Dactylogyrus aristichthys, D. ctenopharyngodonis, D. hypophthalmichthys, D. lamellatus, D. nobilis, D. suchengtaii, Pseudodactylogyrus bini, P. microrchis, and Eudiplozoon nipponicum) were introduced into the Volga River basin accidentally together with the Far Eastern fish species during the process of their naturalization.

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↗