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Results for “TREMATODE INFECTIONS”

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PubMed2000

Spatial and temporal variation of trematode infection in coexisting populations of intertidal gastropods Littorina saxatilis and L. obtusata in the White Sea.

Trematode infection was studied in sympatric populations of the periwinkles Littorina saxatilis and L. obtusata in 2 regions of Kandalaksha Bay of the White Sea to assess host-parasite interactions at the population level. Twenty-seven spatially separated populations were each surveyed in 1984-1994; 2 heavily infected populations were investigated annually over a 16 yr period. Ten trematode species were found in the periwinkle populations. The closest association in spatial distribution and temporal dynamics was observed between 3 ecologically and morphologically similar trematodes of the 'pygmaeus' group: Microphallus piriformes, M. pygmaeus and M. pseudopygmaeus. For these 3 species, the prevalences were closely associated in the 2 host species when spatially separated sites from the 2 studied regions were considered, while in the 2 populations studied over the 16 yr period, a correlation was only observed between the infection levels of L. saxatilis and L. obtusata by either M. piriformes and immature microphallids. Likewise, within each host species, significant correlations were revealed between the prevalence of the different microphallids of the 'pygmaeus' groups. However, they were fewer and weaker when the long-term dynamics of infection in the 2 heavily infected populations were considered. Most other trematodes did not show significant association in prevalence either within or between the 2 host species on spatial and temporal scales.

Analysis of Variance↗
PubMed1994

Intestinal trematode infections in the villagers in Koje-myon, Kochang-gun, Kyongsangnam-do, Korea.

An epidemiological study for the intestinal trematode infection of the villagers was done in Koje-myon, Kochang-gun, Kyongsangnam-do, Korea in March, 1994. Of 116 stool specimens examined, total helminthic ova positive cases were 13 (11.2%) and cumulative ova positive cases 21 (18.1%): Echinostoma hortense 11 cases (9.5%), Metagonimus sp. 6 cases (5.2%), and Clonorchis sinensis 4 cases (3.4%). After the treatment and purgation, variable numbers of E. hortense, 6 to 227 per person, were collected from 7 echinostome egg positive cases, together with M. takahashii in 6 cases. Three adult flukes of E. cinetorchis were collected from one person and one Stellantchasmus falcatus was recovered from another case. This mountainous village was proved to be one of the endemic foci of echinostomiasis in Korea.

Adult↗
PubMed1984

Vector control of snail-mediated human trematode infections.

Inspite of the recent general acceptance of the use of safe and effective chemotherapeutic drugs in the treatment of major human trematode infections, vector control e.g. control of the snail intermediate host will continue to play an important role in programmes for controlling schistosomiasis, clonorchiasis, opisthorchiasis and paragonimiasis. The main vector control measures are: a) use of chemical pesticides or molluscicides and plants showing molluscicidal properties; b) biological control through introduction of competitor species or natural enemies of snails; c) alteration of the environment either by application of one or a combination of the following; drainage, filling, ponding, clearing of vegetation and regulation of use of water for agricultural purposes.

Animals↗
PubMed2001

Six digenetic trematodes infecting the hamour fish (Epinephelus chlorostigma) in the Arabian Gulf, Saudi Arabia.

No doubt, parasites infecting fish have a direct or indirect effect on the human welfare. This paper described six species of trematodes infecting Epinephelus chlorostigma (Family: Serranidae). These parasites were Prosorhynuchus epinepheli, P. thapari, Allopodocotyle epinepheli, Helicometrina nimia, Erilepturus hamati and E. lemeriensis. Camera Lucida and photos were given and the results were discussed.

Animals↗
PubMed2002

Larval trematode infections in freshwater snails from the highveld and lowveld areas of Zimbabwe.

Between November 1998 and October 2000, freshwater snails were collected monthly from the highveld and lowveld areas of Zimbabwe to determine the occurrence of larval trematodes. A total of 13,789 snails, representing ten species, were collected from 21 sites and 916 (6.6%) harboured patent trematode infections. Eight morphologically distinguishable types of cercariae were identified. Bulinus tropicus had the highest overall prevalence of infection (13.1%). The echinostome was the most common type of cercaria recovered, contributing 38.2% of all infections. Schistosoma cercariae were recovered mainly from the highveld and comprised 8.0% of all infections. Amphistome cercariae contributed 37.6% of all infections and were recorded from both the highveld and lowveld areas with a peak prevalence occurring during the post-rainy period (March-May). The main intermediate host for amphistomes was B. tropicus. Infections in B. globosus, B. forskalii and Biomphalaria pfeifferi with amphistome cercariae are new records for Zimbabwe.

Animals↗
PubMed2001

Effects of trematode infection on metabolism and activity in a freshwater snail, Semisulcospira libertina.

Changes in the metabolism and activity of the freshwater snail Semisulcospira libertina infected with larval trematodes were studied experimentally. In snails up to 11 mm in shell width, crawling distance, feeding frequency, and the proportion of individuals located on vertical walls did not differ among snails infected with mature or immature cercariae, or uninfected snails (p > 0.05). In snails larger than 11 mm, individuals infected with mature cercariae tended to feed more frequently during the light period (p = 0.0081), but the distance they crawled and the proportion of individuals located on vertical walls did not differ, regardless of infection (p > 0.05). Infection with mature cercariae significantly increased the oxygen consumption rate (p = 0.016), which was measured only in the large size.

Animals↗
PubMed1990

Humoral response of the snail Biomphalaria glabrata to trematode infection: observations on a circulating hemagglutinin.

The hemolymph of invertebrates often contains molecules that agglutinate vertebrate erythrocytes and that may function as humoral mediators of "non-self" recognition. The objectives of this study were to 1) determine if exposure of M line or 10-R2 strain Biomphalaria glabrata snails to infection with the trematodes Echinostoma paraensei and Schistosoma mansoni could increase agglutinating activity in snail hemolymph, and 2) identify particular hemolymph molecules with such activity. In some host-parasite combinations, such as juvenile M line snails and E. paraensei, infection provoked significant elevations in titer from as early as 2 days postinfection (dpi) through 15 dpi. In other combinations, as with 10-R2 snails and E. paraensei or S. mansoni, host responses were comparatively modest, yet still measurable. In general, E. paraensei and S. mansoni elicited different responses from the same host strain, and M line and 10-R2 snails responded differently to the same parasite. Further study of the response of juvenile M line snails to E. paraensei indicated that hemolymph agglutinating activity could be inhibited by several monosaccharides (including L-fucose) and by EDTA and EGTA. An affinity column containing L-fucose agarose beads was used to purify molecules with agglutinating activity from the hemolymph of such snails. The fraction eluted from the column by 0.2 M L-fucose was shown by SDS-PAGE to contain a broad band of 80-120 kD and, less consistently, a 200 kD band. Following extensive dialysis to remove L-fucose, this fraction had agglutinating activity. As a previous study has shown that the hemolymph of E. paraensei-infected snails contains significantly increased quantities of 80-120 kD polypeptides, it is concluded that polypeptides in this size range are responsible, at least in part, for the increased hemolymph agglutination activity in such snails.

Animals↗
PubMed1991

[Trematode infections in the small intestine of Egretta alba modesta in Kangwon-do].

We surveyed 12 migrating large egrets, Egretta alba modesta, for their infection status with intestinal trematodes, from June to September, 1990. All of them were infected with one or more flukes. Total 5 species were identified. Their infection rates and total numbers of worms were Metagonimus sp. 67% and 1,412, Centrocestus armatus 67% and 2,306, Echinochasmus japonicus 50% and 99, Strigea falconis 83% and 635, and a diplostomid fluke 33% and 36. The number of worms in a bird was in the range from 6 to 896. This is the first record that the egret is a reservoir host of Metagonimus sp., C. armatus, E. japonicus, and S. falconis. S. falconis is a new parasite fauna in Korea. Migrating birds must play an important role in the transmission and spreading of these intestinal trematodes in Korea.

Animals↗
PubMed1991

Intestinal trematodes infecting humans in Korea.

Sixteen species of intestinal trematodes have been recovered from humans in Korea. They include 10 species of the family Heterophyidae (Metagonimus yokogawai, M. takahashii, Heterophyes nocens, H. heterophyes, H. dispar, Heterophyopsis continua, Pygidiopsis summa, Stellantchasmus falcatus, Centrocestus armatus, and Stictodora fuscatum); one species of Diplostomidae (Fibricola seoulensis); three species of Echinostomatidae (Echinostoma hortense, E. cinetorchis, and Echinochasmus japonicus); one species of Plagiorchiidae (Plagiorchis sp.), and one species of Gymnophallidae (Gymnophalloides sp.). Biological and epidemiological studies have shown that all of these species are endemic to Korea except H. heterophyes and H. dispar, which were imported from the Middle East, and Plagiorchis sp., which has not been found in Korea. Several fresh water fish were found carrying metacercarial stages of M. yokogawai, M. takahashii, C. armatus, E. hortense, E. cinetorchis and E. japonicus. Brackish water fish were found to be the second intermediate host of H. nocens, H. continua, P. summa, S. falcatus, and/or S. fuscatum. Terrestrial snakes were the second intermediate (or paratenic) host of F. seoulensis. Among these intestinal flukes, M. yokogawai is the most common one in Korea.

Animals↗
PubMed1990

Distribution of freshwater gastropods in the lower River Niger and Cross River basins of southeastern Nigeria with reference to their trematode infections.

Malacological surveys on the abundance of molluscan fauna were carried out in freshwater habitats at the 2 main rivers of southeastern Nigeria: River Niger and Cross River basins. A total of 19 species of gastropods were found, 13 of which are pulmonates and 6 prosobranchs. The distribution of the species varied between the habitats, with high densities recorded in patches within the habitats. Infected snails were collected mainly from portions of the habitats that are accessible. Trematode cercariae types and infection rates were recorded for each snail species. Seasonal patterns of both snail types and their trematode infection at various developmental stages are discussed.

Animals↗