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PubMed2000

Analysis of 16S rRNA and 51-kilodalton antigen gene and transmission in mice of Ehrlichia risticii in virgulate trematodes from Elimia livescens snails in Ohio.

Operculate snails (the family Pleuroceridae: Elimia livescens) were collected between June and October 1998 from a river in central Ohio where repeated cases of Potomac horse fever (PHF) have occurred. Of collected snails, consistently 50 to 80% carried a combination of cercariae and sporocysts of digenetic virgulate trematodes. The trematodes obtained from each snail were pooled and tested for Ehrlichia risticii, the agent of PHF, by nested PCR using primers specific to the 16S rRNA gene. Out of a total of 209 trematode pools, 50 pools were found to be positive by PCR. The DNA sequence of the 16S rRNA gene identified in one trematode pool was identical to that of the type strain of E. risticii, and the sequence of the gene identified in another pool differed from that of the type strain by 1 nucleotide. Comparison of the deduced amino acid sequence of the partial 51-kDa antigen gene from various sources revealed that Maryland, Ohio (except Ohio 081), and Kentucky strains are in a cluster distinct from the sequences obtained from sources in California and Oregon. Ohio 081 was shown previously by antigenic composition analysis to be distinct from other groups. However, all sequences examined were not segregated according to their sources: horse blood or infected trematodes. E. risticii was found to be transmittable from trematodes to mice and was subsequently passaged from infected mice to additional mice, as determined by PCR analysis. Our findings suggest the evolution of E. risticii in the natural reservoir in separate geographic regions and persistent infection of trematode populations with E. risticii during summer and early fall. The study also suggests that the mouse can be used to isolate E. risticii from the infected trematode.

Amino Acid Sequence↗
PubMed1997

The prevalence of cercariae from Stagnicola emarginata (Lymnaeidae) over 50 years in northern Michigan.

Stagnicola emarginata were collected from 3 northern Michigan lakes and examined for larval trematode infections. The structure of the trematode community was then compared with 2 previous studies conducted on Douglas Lake in order to determine what changes had taken place over a period of more than 50 yr and to examine the possibility of using trematodes as bioindicators of environmental quality. Species richness was reduced by half (from 16 to 8 species) from the first study conducted in 1936, along with a decrease in the overall prevalence from 61% to 13%. No new species had colonized the lake, and the same 8 trematodes were also the only species found in 2 other lakes. The decline in prevalence was most severe in trematodes that used gulls as definitive hosts, whereas species that used ducks as hosts increased slightly. The decrease in species richness and prevalence of infection over time may reflect increasing human impacts on lakes. However, because of patchy host distributions, the use of larval trematodes as bioindicators of environmental change requires further investigation.

Animals↗
PubMed1984

Therapy of fluke infections in the past. A review.

Chemotherapy of trematode infections has been studied intensively in the past. The compounds so far used for the treatment of those parasitic infections were not satisfactory, however, because of their poor tolerability and/or their limited anthelmintic efficacy. Since the introduction of tartar emetic in 1918, a number of antimonial as well as non-antimonial preparations have been used for the treatment of schistosomiasis. In the treatment of clonorchiasis with antimony preparations, gentian violet, emetine HCl, chloroquine diphosphate and dithiazanine iodide, only temporary clinical improvement and negative or reduced egg counts could be achieved, but complete cure was not obtained. Although Hetol (or hexachloroparaxylol), prolonged administration of oral dehydroemetine and only two doses of niclofolan showed therapeutic effect on Clonorchis infection, side effects were observed in most of the treated cases. On the other hand, bithionol proved to be a drug of choice for paragonimiasis. However, the need of multiple doses and the many adverse reactions hampered its use in the field. Recently the newly developed praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino-[2,1-a]+ ++isoquinolin -4-one, EMBAY 8440, Biltricide) proved to be safe and effective against trematodes and appears to be the drug of choice for infections due to all species of Schistosoma, Clonorchis sinensis, Opisthorchis viverrini, Paragonimus spp. and Metagonimus yokogawai in man.

Anthelmintics↗
PubMed2003

Range limits and parasite prevalence in a freshwater snail.

Geographical range limits are thought to be set by species' physiological or ecological adaptation to abiotic factors, but the importance of biotic factors such as parasitism in determining range limits has not been well explored. In this study the prevalence of trematode parasitism in populations of a freshwater gastropod snail, Lymnaea stagnalis, increased sharply as this species approached its western UK range limit. The likelihood of trematode infection increased with snail size, but high prevalence at the range edge was not a result of interpopulation variation in snail size. Changes in population growth rates resulting from high rates of parasitism at the range edge could contribute to range limitation. The mechanism driving high rates of parasitism at the range edge is not clear, but changes in abiotic factors towards the range limit may influence snail life history and immune response to trematode infection, indirectly altering the prevalence of parasites in marginal host populations.

Animals↗
PubMed2005

Epizootiology of spirorchiid infection in green turtles (Chelonia mydas) in Hawaii.

We describe the epizootiology of spirorchiid trematode infections in Hawaiian green turtles (Chelonia mydas) by quantifying tissue egg burdens in turtles submitted for necropsy and by assessing antibody response to crude adult worm and egg antigens among a variety of age groups. Hapalotrema sp. and Laeredius sp. predominated in turtles infected with spirorchiids. Tissue egg burdens decreased with increasing size and increased with deteriorating body condition of turtles. No relationship was found between tissue egg burdens and sex or fibropapillomatosis status. Tissue egg burdens increased in turtles from southeast to northwest in the main Hawaiian Islands (Hawaii to Kauai). Hatchling and captive-reared turtles had significantly lower levels of antibodies against crude worm and egg antigens. Based on tissue egg burdens and antibody status, we hypothesize that immature turtles become infected with spirorchiids shortly after recruiting into coastal foraging pastures from the pelagic environment, that infection levels decrease with age, and that spirorchiids detrimentally affect the body condition of sea turtles independent of tumor burden. The low intensity of infection in turtles with the endemic trematode Carettacola hawaiiensis suggests either that turtles are less susceptible to infection with this parasite or that the parasite is outcompeted by species of Hapalotrema and Laeredius. Given that the 2 latter species are found in the Pacific and other oceans, they are not likely endemic and were probably introduced into Hawaii through an undetermined route.

Animals↗
PubMed2003

Suface topography of adult Anchitrema sanguineum (Sansio, 1894) Looss, 1899 and Prosthodendrium (Prosthodendrium) urna (Looss, 1907) Dollfus, 1931 infecting bats in Upper Egypt (Qena).

Anchitrema sanguineum and Prosthodendrium (Prosthodendrium) urna are two digenean trematodes infecting many species of bats in Egypt. The surface topography of them was studied by scanning electron microscopy. Examination of A. sanguineum revealed the presence of posteriorly directed broadbase spines allover the body. The oral sucker is bordered by several small sucker-like papillae and few irregularly distributed pores. The ventral sucker is smaller than the oral one and surrounded by several papillae. In P. (P.) urna the body is covered with simple, spines posteriorly directed. The oral sucker has few papillae and its tegumental rim slightly elevated. The ventral sucker is slightly larger than the oral one.

Animals↗
PubMed2005

Survival of Haplorchis taichui metacercariae in Lab-Pla, Thai traditional food preparation.

Lab-Pla is a famous kind of Thai traditional food in northern and northeasthern Thailand. Consumption of uncooked Lab-Pla can lead to trematode infection because cyprinoid fish serve as the 2nd intermediate hosts of trematodes. The preparation of Lab-Pla can be made in different ways, depending on seasonings used in different places. The effect of the seasonings used in Lab-Pla on the survival of Haplorchis taichui metacercariae were, therefore, determined. The methodology was done by the following: 100 g of chopped Siamese mud carp fish (Henicorhynchus siamensis) were used for each experiment of seasonings used for completely mixed Lab-Pla. Mixed materials were blended and digested by 1% pepsin solution to obtain metacercariae and then checked for the movement under a stereomicroscope. The results showed that metacercariae remained active in 5 experimental groups: fermented fish treated, fish sauce treated, chili powder treated, ground roasted rice treated, and complete mixed treated indicated by average as follows: 27, 38.7, 33.3, 42.7 and 21%, respectively. In conclusion, fermented fish and completely mixed methods have more effectiveness in killing metacercariae in Lab-Pla preparation than other seasonings (p < 0.05).

Animals↗
PubMed1997

Fasciola gigantica and F hepatica: a comparative study of some characteristics of Fasciola infection in Lymnaea truncatula infected by either of the two trematodes.

Experimental infections were carried out using three Lymnaea truncatula populations and two Fasciola species in order to determine the trematode influence on six parameters of snail infection by either of the two trematodes. All experiments were performed using snails 4 mm long, two miracidia for each L truncatula, and a constant temperature of 20 degrees C. No significant influence of trematode species was detected in the following parameters: snail survival at day 30, the life span of infected snails (from miracidial exposure to snail death), the increase in shell length throughout the experiment, the duration of the patent period and the number of cercariae shed by infected snails. The frequency of cercaria-shedding snails was closely correlated with the particular L truncatula population and trematode species. A similar finding in two populations was also noted for the frequencies found in the infected snails who died without emission. The prepatent period had a longer duration in the Fasciola gigantica-infected groups. The percentages of floating cysts were greater in the Fasciola gigantica groups than in the Fasciola hepatica groups.

Animals↗
PubMed2004

Effects of Schistosoma mansoni infection on inorganic elements in the snail Biomphalaria glabrata.

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to study element ions in whole bodies of uninfected Biomphalaria glabrata snails and those experimentally infected with larval Schistosoma mansoni trematodes. Infected snails were analysed 8 weeks post-infection. Cohort snails that were left uninfected were analysed at the same time as the infected snails. Sixteen elements (aluminum, boron, barium, calcium, cadmium, copper, iron, potassium, magnesium, manganese, sodium, nickel, lead, selenium, tin and zinc) were found to be present in infected and uninfected whole bodies at concentrations above the detection limit of the ICP-AES analysis. Of these, calcium, cadmium, manganese and sodium were present in significantly higher amounts (Student's t-test, P<0.05) in whole infected versus whole uninfected snails. Variations in the present results compared with other studies reflect intrinsic differences in the larval trematode-snail systems used.

Animals↗
PubMedDate not supplied

[Effect of trematoda infection and different concentrations of surface active agents onto physical and chemical characteristics of haemolymph of Planorbarius corneus (Mollusca: Pulmonata)].

Effect of trematod infection and different concentrations of detergent (20, 50, 80 mg/dm3) onto physical and chemical characteristics of haemolymph of Planorbarius corneus (content of Hb, density, active reaction, amount of Hb per unit of total mass and soft mass of the body) have been investigated. It was noted that all changes of named characteristics caused by detergent were more pronounced in infected mollusks.

Animals↗
PubMed2001

Snail-trematode life history interactions: past trends and future directions.

Life history traits expressed by organisms vary due to ecological and evolutionary constraints imposed by their current environmental conditions and genetic heritage. Trematodes often alter the life history of their host snails by inducing parasitic castration. Our understanding of the variables that influence the resulting changes in host growth, fecundity and survivorship is insufficient to confidently predict specific outcomes of novel snail-trematode combinations. In a literature review of the last 30 years, we found 41 publications examining various life history characteristics of trematode-infected snails. These publications reported 113 different field and laboratory experiments involving 30 snail species and 39 trematode species and provided a data set for assessing factors that potentially affect life history outcomes. Analysis of the diverse responses across various snail-trematode systems and experimental conditions teased out general patterns for the expression of host growth, fecundity and survival. These were used to address existing hypotheses and develop several new ones relating the response of snail-trematode interactions to environmental and genetic factors. Finally, we propose directions for future experiments that will better assess the ecological and evolutionary factors influencing snail life history responses to trematode parasitism.

Animals↗
PubMed1988

Echinostoma population regulation in experimental rodent definitive hosts.

Echinostoma population regulation in the experimental rodent host is governed by the capacity of the latter to express an effective regulatory response. Parasite establishment, survival and fecundity are affected by host-related factors such as species, strain and age and by parasite-related factors such as species, age and the burden of infection. The genetic heterogeneity in the regulatory response to infection is marked. The most intensively studied host/echinostome combinations comprise E. caproni and E. trivolvis in the mouse host, for which a range of interesting host-parasite relationships has been demonstrated, including concomitant immunity with rapid expulsion of superimposed infections, a long-lasting resistance to secondary infection, a negatively dose-dependent pattern of expulsion of primary infections, a positively dose-dependent reproductive potential, an infective-dose independency of primary worm establishment, and a range of heterologous antagonistic and synergistic interactions in concurrent infections with related and unrelated parasite species. The Echinostoma/rodent model is highly suitable for studying aspects of parasite population regulation in intestinal trematode infections.

Animals↗
PubMed1984

Liver carcinoma and liver fluke infection.

The neoplastic transformation of bile duct changes induced by infections due to Clonorchis sinensis or Opisthorchis viverrini has been persistently debated because of the difficulty to establish the causative relation between those trematode infections and the development of primary carcinoma of the liver (PCAL) which has been found in Hong Kong, China, Korea and Thailand. The following observations, however, clearly support the hypothesis that clonorchiasis and opisthorchiasis are basic etiological factors of the pathogenesis of human cholangio-carcinoma (CC): C. sinensis and O. viverrini infections lead to quite similar tissue reactions in bile ducts, starting with desquamation of epithelial linings with subsequent development of adenomatous hyperplasia and periductal fibrosis besides inflammatory cellular exudation and goblet cell metaplasia in both man and experimental animals. The majority of PCAL are of the hepatocellular type but as to CC, the prevalence rate is much higher in those areas where C. sinensis and O. viverrini infections are endemic. Histologically, the neoplastic transformation from adenomatous hyperplasia in bile ducts to CC through dysplastic changes of lining cells or from cholangiofibrosis is clearly demonstrable. Furthermore, mucin-producing activity is also a frequent feature to reflect the neoplastic transformation of the metaplastic goblet cell change of the bile duct linings. Application of various carcinogens to liver fluke infected animals cause a higher incidence of CC than is the case in non-infected controls. These epidemiological and histopathologic characteristics seem to indicate that C. sinensis and O. viverrini are predisposing conditions for the pathogenesis of CC in Southeast and East Asian countries.

Adenocarcinoma, Mucinous↗
PubMed2001

An outbreak of trematode-induced granulomas of the conjunctiva.

PURPOSE: To describe the epidemiologic, clinical, and histopathologic features of trematode granulomas of the conjunctiva, eyelid, and anterior chamber in pediatric patients. DESIGN: Prospective noncomparative case series. PARTICIPANTS: Forty-one children from a southern Indian village with conjunctival granulomas. METHODS: The village of Sellananthal was selected for a field visit after analysis of earlier hospital-based allergic conjunctival granuloma cases. Children with ocular diseases were examined, and histories of exposure to assumed risk factors and clinical findings were evaluated. Selected patients were brought to the base hospital for excisional biopsy. Serial sections obtained from the excised nodules were examined for the presence of a parasite. MAIN OUTCOME MEASURES: Histopathologic examination of excised conjunctival lesions or response of lesions to local medical therapy. RESULTS: In this year-long prospective study, 41 children (16 years or younger; 38 boys and 3 girls) with clinical features of allergic conjunctival granulomas were examined. Thirty-four patients were from a single village located in the southern Indian state of Tamil Nadu; the remaining 7 were from various parts of the same state. All children swam in their village's freshwater pond. Twenty patients with nodules less than 5 mm in diameter received medical treatment; 13 with larger nodules underwent surgical excision of the lesions. Nine of these 13 cases revealed a zonal granulomatous inflammation admixed with eosinophilic leukocytes; 4 of these 9 displayed fragments of the tegument and internal structures of a trematode and Splendore-Hoeppli phenomenon. The remaining 4 of the 13 cases revealed nongranulomatous inflammation made up of lymphocytes, histiocytes, and eosinophils. Eight patients refused surgical treatment. CONCLUSIONS: In southern India, one cause of allergic conjunctival granulomas in children seems to be trematode infection. The clustering of cases in a single village and exposure to a village freshwater pond indicate the need for an epidemiologic investigation and study of the parasite's life cycle. Sporadic cases from other parts of the state with similar histories of exposure to their local pond or river water suggest a widespread distribution of the etiologic agent.

Adolescent↗
PubMed2006

Adding infection to injury: synergistic effects of predation and parasitism on amphibian malformations.

We explored the importance of interactions between parasite infection and predation in driving an emerging phenomenon of conservation importance: amphibian limb malformations. We suggest that injury resulting from intraspecific predation in combination with trematode infection contributes to the frequency and severity of malformations in salamanders. By integrating field surveys and experiments, we evaluated the individual and combined effects of conspecific attack and parasite (Ribeiroia ondatrae) infection on limb development of long-toed salamanders (Ambystoma macrodactylum). In the absence of Ribeiroia, abnormalities involved missing digits, feet, or limbs and were similar to those produced by cannibalistic attack in experimental trials. At field sites that supported Ribeiroia, malformations were dominated by extra limbs and digits. Correspondingly, laboratory exposure of larval salamanders to Ribeiroia cercariae over a 30-day period induced high frequencies of malformations, including extra digits, extra limbs, cutaneous fusion, and micromelia. However, salamander limbs exposed to both injury and infection exhibited 3-5 times more abnormalities than those exposed to either factor alone. Infection also caused significant delays in limb regeneration and time-to-metamorphosis. Taken together, these results help to explain malformation patterns observed in natural salamander populations while emphasizing the importance of interactions between parasitism and predation in driving disease.

Ambystoma↗
PubMed2002

Presumed trematode-induced granulomatous anterior uveitis: a newly recognized cause of intraocular inflammation in children from south India.

PURPOSE: To describe the epidemiologic, clinical, and histopathologic features of a presumed trematode granulomatous anterior uveitis, primarily in children from south India. DESIGN: Prospective, noncomparative, case series. METHODS: Children with clinical evidence of granulomatous anterior uveitis were selected for the study. Those who presented with distinct anterior chamber nodules were evaluated. Demographic details, such as clinical findings and course of illness, were noted. Patients underwent either medical treatment or surgical aspiration of the lesion based on the size of the lesion. Aspirated materials were subjected to histopathologic analysis and cultures for bacteria and fungi. Response to treatment and final visual status were evaluated. RESULTS: One hundred thirteen patients with anterior chamber nodules were seen between 1998 and 2000. Ninety-three (82.4%) were males and 20 (17.7%) were females. The median age was 11.0 years. All patients were from south India and all gave a history of bathing or swimming in the local pond or river. All had normal systemic work ups. Of the 113 patients, 110 had anterior chamber nodules and three had both anterior chamber and subconjunctival nodules. Aspirates of the anterior chamber lesions revealed lymphocytes, intact and necrotic neutrophils, and eosinophils admixed with histiocytes. One subconjunctival nodule showed necrotizing granuloma, displaying the tegument of a trematode. Those patients who were followed had good visual recovery after medical or surgical intervention or both. CONCLUSION: The present study shows a newly recognized granulomatous anterior uveitis caused by a presumed water-borne trematode infection. This infection appears to be a common cause of pediatric granulomatous anterior uveitis in south India.

Adolescent↗