Showing papers in "Journal of Helminthology in 1997"
TL;DR: The main objective is to combine interrelated European expertise to increase the use of entomopathogenic nematodes in integrated pest management and to reduce the need for chemical control.
Abstract: COST Action 819: Entomopathogenic nematodes, supercedes Action 812: Cold active lines of insect parasitic nematodes in Agriculture and Biotechnology. It functions in the field of Agriculture and Biotechnology and began in July 1994 and will end in May, 1999. The main objective is to combine interrelated European expertise to increase the use of entomopathogenic nematodes (EPNs) in integrated pest management and to reduce the need for chemical control. Coordination of the Action is the responsibility of a management committee in accordance with a Memorandum of Understanding, which has been signed by representatives of 17 countries: Austria, Belgium, Czech Republic, Finland, France, Germany, Hungary, Ireland, Italy, The Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland and the UK. A research institute in Israel is also participating. Over 40 research institutions and 10 commercial companies participate in Action 819. The EU funding meets the costs related to coordination including the scientific secretariat, workshops, management committee and working group meetings, publications, short term scientific missions and evaluations.
199 citations
TL;DR: Future studies will monitor the spread of human urinary and mesenteric schistosomiasis in the SRB, evaluate further the presence of praziquantel resistance/tolerance in S. mansoni, examine the heavily infected human population for pathological symptoms and determine the most appropriate methods to control this severe outbreak of human schistOSomiasis.
Abstract: Ecological changes in the Senegal River Basin (SRB) resulting from the construction of a barrage at Diama, Senegal on the Senegal River to prevent the intrusion of sea water into the river, and a dam at Manantali, Mali on the Bafing River to control the flow of water and to generate electricity, have been responsible for changes in the epidemiology of human schistosomiasis. The introduction of Schistosoma mansoni into the Lower and Middle Valleys of the SRB and subsequent spread of the parasite in the human population is recorded with regard to prevalence and intensity. New foci of S. haematobium are described. The reduction in salinity and change from an acidic to an alkaline environment in the water are beneficial to both the fecundity and growth of freshwater snails and transmission of the parasite. The creation of new irrigation canals and expansion of the rice fields have provided new habitats for intermediate hosts to colonize. The evidence for praziquantel resistance/tolerance by populations of S. mansoni and the possibilities of the development, production and testing of a vaccine against human schistosomiasis are discussed. Future studies will monitor the spread of human urinary and mesenteric schistosomiasis in the SRB, will evaluate further the presence of praziquantel resistance/tolerance in S. mansoni, will examine the heavily infected human population for pathological symptoms and determine the most appropriate methods to control this severe outbreak of human schistosomiasis.
123 citations
TL;DR: A cross-sectional study on the prevalence of helminths in rural scavenging poultry on six hundred adult chickens selected randomly from six villages in the Morogoro Region, Tanzania during the wet and the dry seasons, found no correlation was found between season and prevalence, or season and mean worm burdens.
Abstract: A cross-sectional study on the prevalence of helminths in rural scavenging poultry on six hundred adult chickens selected randomly from six villages in the Morogoro Region, Tanzania during the wet and the dry seasons, was conducted. The trachea and gastrointestinal tract of each bird were examined for the presence of parasites. All chickens were infected with one or several species of helminths, the average being 4.8 ±1.7 helminths per chicken during the wet season and 5.1 ± 1.8 during the dry season. A total of 29 different helminth species were shown in the trachea or the gastrointestinal tract. The following species were identified: Syngamus trachea (0.7% (wet season), 2% (dry season)); Gongylonema ingluvicola (6.3%, 17.7%); Tetrameres americana (54.3%, 60.3%); Dispharynx nasuta (0%, 2.7%); Acuaria hamulosa (8.3%, 19.3%); Ascaridia galli (28.3%, 32.3%); Heterakis gallinarum (74.0%, 78.7%); H. isolonche (18.7%, 5.0%); H. dispar (25.7%, 6.3%); Allodapa suctoria (40.0%, 52.0%); Subulura strongylina (3.3%, 1.0%); Strongyloides avium (0.3%, 3.0%); Capillaria annulata (2.0%, 0.0%); C. contorta (9.0%, 1.0%); C. caudinflata (2.0%, 4.3%); C. obsignata (8.7%, 25.0%); C. anatis (4.0%, 9.0%); C. bursata (1.0%, 2.7%); Raillietina echinobothrida (41.3%, 46.3%); R. tetragona (25.3%, 21.3%); R. cesticillus (8.7%, 2.7%); Choanotaenia infundibulum (0.0%, 3.7%); Hymenolepis carioca (9.0%, 18.0%); H. cantaniana (48.0%, 43.0%); Amoebotaenia cuneata (39.3%, 36.0%); Metroliasthes lucida (1.0%, 0.3%); Davainea proglottina (5.7%, 0.3%) and Polymorphus boschadis (0.3%, 0.0%). No trematodes were found. No correlation was found between season and prevalence, or season and mean worm burdens. Twelve helminths of the species recovered represent new local records.
98 citations
TL;DR: Twenty species of helminth parasites were identified from fox, wolf, jackal and wild cat material collected in Greece, with the species J. echinorhynchoides, Taenia crassiceps and Onicola canis and the genera Spirometra, Rictularia and Pachysentis reported here for the first time in Greece.
Abstract: Twenty species of helminth parasites were identified from fox, wolf, jackal and wild cat material collected in Greece. Of the 314 foxes (Vulpes vulpes) examined, 18 helminth species were recovered comprising one trematode, eight cestodes, seven nematodes and two acanthocephalans, with the cestode species Mesocestoides sp. (73.2%), Joyeuxiella echinorhynchoides (24.5%) and the nematode species Uncinaria stenocephala (43.9%), and Toxara canis (28.6%) being the most prevalent. Five cestode and three nematode species were reported from six wolves (CaniS lupus), together with one trematode, three cestode and four nematode species from five jackals (Canis aureus) and two cestode and three nematode species from four wild cats (Felis silvestris) examined. The species J. echinorhynchoides, Taenia crassiceps and Onicola canis and the genera Spirometra, Rictularia and Pachysentis are reported here for the first time in Greece. The results are discussed in the light of the feeding characteristics of wild carnivores in rural areas of Greece.
67 citations
TL;DR: The programme has constantly monitored the impact of operations on the trends in prevalence, incidence, annual transmission potential, ocular morbidity and species of fly populations, and has identified areas where special interventions are required until the programme comes to an end in 2002.
Abstract: This paper summarizes the work of the Onchocerciasis Control Programme (OCP) in West Africa, a programme which over a 22 year history has reduced the public health problems of blinding onchocerciasis in eleven countries of West Africa through vector control and, more recently, ivermectin distribution. The paper emphasizes the different approaches to control the programme has developed in the different parts of the programme area which have been determined by the epidemiology of the disease (savanna/forest form), the migratory characteristics of the vectors, intensity of the disease before commencement of treatment, the combined impact of vector control and ivermectin and the likelihood of infiltration of infective blackflies from outside the programme area. The programme has constantly monitored the impact of operations on the trends in prevalence, incidence, annual transmission potential, ocular morbidity and species of fly populations, and as a result, has identified areas where special interventions are required until the programme comes to an end in 2002. The paper illustrates the changes in intensity of infection as measured by community microfilarial load and annual transmission potential over the duration of the programme control activities. The paper also defines and justifies the control strategies in different areas and identifies areas for special interventions.
53 citations
TL;DR: The findings provide further and unexpected support for the view that some factor(s) other than supply side ones must be operating to produce the fundamental structural similarity in helminth communities in eels.
Abstract: The composition and diversity of total and intestinal helminth component and infracommunities were determined in eels Anguilla anguilla from four shallow coastal lagoons near Rome. The lagoons differed principally in respect of their salinity. Only Lake Burano still received an input of freshwater, and both freshwater and marine helminth species were found in eels. In the other three lagoons all helminth species were marine or euryhaline and communities were dominated by digeneans. At component community level these three lagoons were far more similar to each other than to Lake Burano, but this distinction almost disappeared at infracommunity level. Species richness and diversity declined with increasing salinity at component community level but not at infracommunity level. Despite the changes and differences in helminth community composition, intestinal helminth infracommunity structure was very similar in all four lagoons and to that in eels from freshwater localities in Britain. The findings thus provide further and unexpected support for the view that some factor(s) other than supply side ones must be operating to produce the fundamental structural similarity in helminth communities in eels.
49 citations
TL;DR: The desiccation survival and ability to control water loss during drying of individual infective juveniles (IJs) of populations of Steinernema feltiae and Heterorhabditis megidis from Greece and the UK were examined at different relative humidities.
Abstract: The desiccation survival and ability to control water loss during drying of individual infective juveniles (IJs) of populations of Steinernema feltiae and Heterorhabditis megidis from Greece and the UK were examined at different relative humidities. Survival at all relative humidities was for minutes only and there was no evidence of enhanced survival of the populations of either species from Greece compared with those from the UK. The survival of individuals of both populations of H. megidis was superior to that of S. feltiae and the rate of drying of H. megidis was significantly slower. The sheath surrounding the IJs of H. megidis appears to be involved in slowing the rate of water loss of the enclosed nematodes.
48 citations
TL;DR: A survey of 612 black rats, Rattus rattus, for infections with helminth parasites was carried out in Abeokuta, in southwest Nigeria, finding that rats of 100-130 g were more infected and had the highest mean intensity, MI, which has considerable public health implications.
Abstract: A survey of 612 black rats, Rattus rattus (282 males and 330 females), for infections with helminth parasites was carried out in Abeokuta, in southwest Nigeria. Three hundred and ninety six (64.7%) were infected with one or more of seven species of helminths comprising three cestodes (Hymenolepis diminuta, Taenia taeniaeformis (cyst) and Raillietina sp.) three nematodes (Mastophorus muris, Trichuris muris and Syphacia sp.) and one acanthocephalan (Moniliformis moniliformis). Although the prevalence of infection in males (76.6%) was more than in females (54.5%) (P 130g (73.9%, MI = 9.3). Moniliformis moniliformis was the most common species encountered (39.2%) and had the highest mean intensity in both sexes ( = 7.4 ± 0.74). Considering the rat-man proximity, this finding has considerable public health implications.
47 citations
TL;DR: Additional genetic data are presented in support of the synonymy of the Paragonimus ohirai group, finding that the three forms can exchange genes freely, and that differences in metacercarial morphology constitute a polymorphism probably due to a single gene inherited in Mendelian fashion.
Abstract: The Paragonimus ohirai group, named after P. ohirai Miyazaki, 1939, consists of three nominal species. Paragonimus iloktsuenensis Chen, 1940 and P. sadoensis Miyazaki et al., 1968, the other members of the group, were proposed primarily because of perceived differences in metacercarial morphology and/or host preferences. It has long been recognized that adults of the three were virtually indistinguishable. With the application of genetic techniques, it has become clear that the three forms can exchange genes freely, and that differences in metacercarial morphology constitute a polymorphism probably due to a single gene inherited in Mendelian fashion. Here, additional genetic data (DNA sequences from the second internal transcribed spacer of the nuclear ribosomal gene cluster and from the mitochondrial cytochrome c oxidase subunit I gene) are presented in support of the synonymy.
44 citations
TL;DR: In this paper, an attempt was made to find associations between parasite richness and various characters of the hosts and no clear correlation was found with maximal size, although the smallest species (less than 10 cm) seem to never harbour monogeneans.
Abstract: Monogenean richness of marine fish is highly variable among host families and species. On the basis of 160 fish species selected because their parasite fauna was considered as ‘adequately’ investigated, an attempt was made to find associations between parasite richness and various characters of the hosts. No clear correlation was found with maximal size, although the smallest species (less than 10cm) seem to never harbour monogeneans. Correlations were found with nectonic, migrating and gregarious behaviours. However, taxonomy of fish appears to be extremely important as a determinant of monogenean richness. In the absence of a satisfactory phylogeny of hosts, no attempt was made to control the analysis for phylogeny. However, removing some families characterized by a high parasite richness (sparids, sciaenids, mugilids) shows that the association with gregariousness holds, whereas the others tend to disappear.
39 citations
TL;DR: If one considers only those papers published in Parasitology, they provide a record of intellectual vigour and curiosity that has remained undiminished throughout Donald Lee's career.
Abstract: I was delighted to be able to join with so many friends and colleagues, in writing this short paper to mark the retirement of Donald Lee. There are many outstanding milestones in Donald's career. However, I thought that I could perhaps draw special attention to his long and distinguished association with the British Society for Parasitology (BSP), and the journal, Parasitology. He was President of the BSP between 1978 and 1980 and, in recognition of his service to the Society and contributions to the discipline of parasitology, was elected an Honorary Member in 1980. Donald has also had a long association with Parasitology, as a member of the Editorial Board and as a frequent contributor. His first paper in the journal was published in 1958; it described the occurrence of Syngamus sp. in a fieldfare (Turdus pilaris) that had been accidentally killed. At the time of writing, his most recent publication, but I suspect not his last, was a biochemical study on proteins produced by Nippostrongylus brasiliensis, Nematodims battus and Ascaridia galli (Foster & Lee, 1996). Of course, Donald has published in many other journals and authored several books. However, if one considers only those papers published in Parasitology, they provide a record of intellectual vigour and curiosity that has remained undiminished throughout his career.
TL;DR: Intestinal helminth parasites are responsible for a significant amount of pathology in both humans and farmed animals, resulting in a reduction in the quality of life, and occasionally lethal infection as well as causing decreases in livestock productivity.
Abstract: Intestinal helminth parasites are responsible for a significant amount of pathology in both humans and farmed animals, resulting in a reduction in the quality of life, and occasionally lethal infection as well as causing decreases in livestock productivity. The importance of these parasites globally has resulted in efforts to understand the mechanisms of the host-parasite interaction epidemiology, and to develop methods for diagnosis and control. Helminth infection of the gastrointestinal tract (GI) may involve the three main groups: cestodes, nematodes
TL;DR: In this article, the authors investigated differences in detoxification enzymes between the parasite and its host and found that selective inhibition of the parasites protective enzymes could increase their sensitivity to drug action and also make them more susceptible to the host's defence mechanisms.
Abstract: Detoxification mechanisms in parasitic helminths have not been extensively studied, despite their obvious relevance to drug development and drug resistance Differences in detoxification enzymes between the parasite and its host may be exploitable in the design of pro-drugs, whilst selective inhibition of the parasites protective enzymes could increase their sensitivity to drug action and also make them more susceptible to the host's defence mechanisms
TL;DR: The migratory pathway of Toxocara canis larvae was determined by infecting mice with a low, medium or high dose of embryonated T. canis eggs and determining numbers of larvae present in the brain, liver, lungs, kidneys and muscle on days 5, 14 and 26 post infection.
Abstract: The migratory pathway of Toxocara canis larvae was determined by infecting mice with a low, medium or high dose of embryonated T. canis eggs and determining numbers of larvae present in the brain, liver, lungs, kidneys and muscle on days 5, 14 and 26 post infection. Variation was seen in the numbers of larvae recorded in the organs of mice which had received the same number of eggs and were at the same stage of infection. This variation was particularly marked in the brain indicating that, for the purposes of behavioural studies, the actual numbers of larvae found in the brain rather than the number assumed from the dose would have to be taken into account when analysing the behaviour of infected mice.
TL;DR: All three strains of Neotricula aperta sampled from populations in northeast Thailand were found to be compatible with a Schistosoma mekongi isolate from Kratie District, eastern Cambodia, and the greater infectivity to the gamma-strain was statistically significant.
Abstract: All three strains of Neotricula aperta (Gastropoda: Pomatiopsidae) sampled from populations in northeast Thailand were found to be compatible with a Schistosoma mekongi isolate from Kratie District, eastern Cambodia. The infection rates were: 3.0%, alpha-strain; 6.0%, beta-strain, and 20.5%, gamma-strain. The greater infectivity to the gamma-strain, over both the alpha- and beta-strains, was statistically significant. Comparisons of infectivity patterns for the Kratie isolate, with those described in earlier studies using S. mekongi isolates from southern Laos, revealed differences among the strains. The gamma-strain of N. aperta is responsible for endemic transmission of human schistosomiasis in southern Laos and at Kratie. Consequently, the findings of this study are of use in the prediction of changes in the distribution of Mekong schistosomiasis, particularly its introduction to northeast Thailand from the neighbouring countries, Cambodia and Laos.
TL;DR: Primers for polymerase chain reaction to amplify genomic DNA of both Toxocara canis and T. cati were constructed by adapting cloning and sequencing random amplified polymorphic DNA.
Abstract: Primers for polymerase chain reaction to amplify genomic DNA of both Toxocara canis and T. cati were constructed by adapting cloning and sequencing random amplified polymorphic DNA. The primers are expected to detect eggs and/or larvae of T. canis and T. cati, both of which are known to cause toxocariasis in humans.
TL;DR: Different organs and secretions/excretions of the swimbladder parasite, Anguillicola crassus (Nematoda), were tested for the presence of antigens to the humoral immune response previously detected in the European eel, AngUilla anguilla.
Abstract: Different organs and secretions/excretions of the swimbladder parasite, Anguillicola crassus (Nematoda), were tested for the presence of antigens to the humoral immune response previously detected in the European eel, Anguilla anguilla. Proteins from different fractions of Anguillicola crassus were separated using SDS-PAGE (sodium-dodecyl-sulphate polyacrylamide-gel electrophoresis) under reducing conditions and electroblotted onto nitrocellulose membranes. Infected eels showed a specific antibody response to a 43 kDa antigen in the cuticle and towards two gonad antigens around 34 and 43 kDa. In protein released from the worms, two secretory/excretory antigens of approximately 28 kDa were found. The secretion/excretion rate of protein from the parasite to the surroundings was determined. Subsequently, an ELISA system was established applying these antigens as the first layer of coating. Furthermore, antigens from Anguillicola crassus were examined for the presence of glutathione-s-transferase (GST) using a specific antibody against GST. The antigens were found to be subunits of GST.
TL;DR: The life-cycle of the tapeworm Bothriocephalus claviceps (Goeze, 1782) (Cestoda: Pseudophyllidea), a specific parasite of eels, was studied under experimental conditions and perch and guppies were shown to serve as paratenic hosts of the parasite.
Abstract: The life-cycle of the tapeworm Bothriocephalus claviceps (Goeze, 1782) (Cestoda: Pseudophyllidea), a specific parasite of eels (Anguilla spp.), was studied under experimental conditions. It was demonstrated that the parasite completed its development within 4 months at the temperature range of 22-24 degrees C. Embryonic development was finished in 2 days at this temperature, when coracidia spontaneously hatched. The rate of their development was controlled by water temperature, with delayed formation of coracidia at lower temperatures (8 days at 10-12 degrees C). At 2-4 and 6 degrees C, development did not take place but the eggs remained viable; at 33 degrees C the eggs died. The procercoids developed in copepods of the species Macrocyclops albidus, M. fuscus, Megacyclops viridis, Cyclops strenuus, C. vicinus and Acanthocyclops vernalis (Copepoda: Cyclopidae); their development was finished after 8-12 days at 22-24 degrees C. The definitive hosts, eels, acquired infection after ingestion of infected copepods; the prepatent period of the parasite was more than three months. Perch (Perca fluviatilis) and guppies (Poecilia reticulata) were shown to serve as paratenic hosts of the parasite; in guppies, the tapeworms survived up to 14 days after exposure and they developed similarly to tapeworms in the definitive host.
TL;DR: Data regarding seasonal trends in the acquisition of D. phoxini indicated that fish in both populations become infected with the parasites mainly during the spring and summer, with negligible infection occurring during winter months.
Abstract: Data are presented on the infection dynamics of the brain-dwelling metacercariae of Diplostomum phoxini (Digenea: Trematoda) parasitizing European minnow (Phoxinus phoxinus) populations in a lowland river (River Endrick) and a highland loch (Loch Maragan) in central Scotland. Prevalence of the parasite approached 100% in all samples taken from both populations over a 12-month period, and within each population the intensity of infection increased with increasing host fork length. However, the two relationships differed, and size-matched minnows from the Endrick exhibited significantly higher intensities than those from Loch Maragan, suggesting that metacercarial acquisition occurred at different rates in the two populations. Data regarding seasonal trends in the acquisition of D. phoxini indicated that fish in both populations become infected with the parasites mainly during the spring and summer, with negligible infection occurring during winter months. Analysis of size-matched fish from individual samples revealed apparent differences in the distribution of D. phoxini within the two host populations. Whereas D. phoxini metacercariae appeared to be overdispersed amongst length-matched fish from Loch Maragan samples, the parasite was distributed normally amongst fish from the Endrick. Possible reasons for the observed differences in the infection characteristics of D. phoxini in the two minnow populations are discussed, with reference to the parasite's transmission dynamics and local environmental conditions.
TL;DR: Sera from patients with clinical characteristics of toxocariasis were assayed using the ELISA method and larval excretory-secretory antigen to derive Toxocara seroprevalences in the rural and urban areas of Galicia, Spain.
Abstract: Sera from patients with clinical characteristics of toxocariasis were assayed using the ELISA method and larval excretory-secretory antigen. Four hundred and seven samples of Toxocara serology were received at the laboratory of ‘Ciudad Sanitaria Juan Canalejo’ Hospital of Corunna, Spain, from 1984 to 1989. Of these, 30 were from adults, 332 from children and 45 from patients of unknown age, resulting in Toxocara seroprevalences of 23.3%, 32.8% and 17.7% respectively. The reasons for these serological differences in the rural and urban areas of Galicia, Spain are discussed.
TL;DR: Female mice of nine inbred strains and H-2 congenic B10 resembled C57BL/10 in prohibiting the development of protoscoleces, suggesting that the qualitative difference in hydatid development may be regulated by non-H-2 gene(s).
Abstract: Female mice of nine inbred strains (A, AKR, BALB/c, C3H, C57BL/6, C57BL/10, CBA, DBA/1 and DBA/2) and H-2 congenic B10.D2, at 9-10 weeks of age, were infected with larval Echinococcus multilocularis by trans-portal injection of hydatid homogenate. Parasitized livers were histologically examined 9 or 13 weeks after infection. Hydatid development was quite different among mouse strains. Multivesiculation was prominent in C57BL/10, DBA/1, C57BL/6 and BALB/c. Protoscoleces were well developed in DBA/2, AKR, DBA/1 and CBA. H-2 congenic B10.D2, which has the background genes of C57BL/10 except for the H-2d gene of DBA/2, resembled C57BL/10 in prohibiting the development of protoscoleces. These data suggest that the qualitative difference in hydatid development may be regulated by non-H-2 gene(s).
TL;DR: It was concluded that the outer cyst layer was the product of secretory granules which were previously identified in cercarial tegument which accumulated in the cyst lumen for some time before becoming polymerized to form the thick inner layer or layers of the metacercarial cysts.
Abstract: This study deals with the formation of the metacercarial cysts of four microphallid trematodes, Maritrema subdolum, M. arenaria, Levinseniella brachysoma and Microphallus claviformis. The first observable cyst was present around Maritrema arenaria 18 h p.i. (post-infection). The other species had not developed a cyst by day 8 p.i. but their cysts were apparent by day 16 p.i. These were bi-layered and that of M. subdolum was thicker than those of L. brachysoma and Microphallus claviformis of the same age. The structure of older cysts varied substantially between the four species. Microphallus claviformis and Maritrema subdolum cysts were fully formed at 30 days p.i. Like those of M. arenaria they were bi-layered, the outer layer (up to 3 microm thick) being electron-dense and the inner one (up to 7 microm thick) being less electron-dense. The cysts of fully formed L. brachysoma metacercariae were much more complex, composed of four layers, one of which was divisible into three sub-layers. It was concluded that the outer cyst layer was the product of secretory granules which were previously identified in cercarial tegument. The inner, thicker layer was derived from several sources. These included small tegument vesicles produced over the entire surface of the metacercariae, larger fragments of tegument released from the anterio-ventral region and material liberated from the metacercarial excretory bladder. This heterogeneous material accumulated in the cyst lumen for some time before becoming polymerized to form the thick inner layer or layers of the metacercarial cysts.
TL;DR: Differences in in vitro vesicular development in three Spanish strains of Echinococcus granulosus are reported, and it is possible to consider the sheep strain as the most likely source of human infections in Spain.
Abstract: Differences in in vitro vesicular development (microcyst formation) in three Spanish strains of Echinococcus granulosus (sheep-cattle, horse and pig-goat) are reported. Microcyst formation occurred in 19-37 days (sheep strain), 9-18 days (pig strain) and 35-47 days (horse strain). Comparing these results with those from human samples (microcyst formation in 24-38 days), it is possible to consider the sheep strain as the most likely source of human infections in Spain.
TL;DR: The results show that S. feltiae infective juveniles which subsequently become female have a greater probability of invasion into test hosts than their male counterparts, which leads to markedly female biased sex ratios during the initial stages of the infection interaction.
Abstract: An infection experiment was conducted to assess the change in the proportions of Steinernema feltiae Filipjev (Site 76 strain) infective juveniles becoming male or female on exposure to the test host Galleria mellonella L. Using a mathematical model for the infection interaction, the per capita probability of penetration per unit time (transmission coefficient), for those juveniles becoming male or female, and the magnitude of the male and female classes in the infective juvenile pool were estimated. The results show that S. feltiae infective juveniles which subsequently become female have a greater probability of invasion into test hosts than their male counterparts, which leads to markedly female biased sex ratios during the initial stages of the infection interaction. As the infection progresses, however, it was found that the sex ratio became balanced. This was because the underlying sex ratio in the infective stage pool was balanced. The implications of this dynamism in the sex ratio of the entomopathogenic nematodes are discussed with respect to the infection interaction, transmission and the likely environment in which the infective juveniles reside.
TL;DR: The larval development of Dicrocoelium dendriticum in experimentally infected Cernuella (Xeromagna) cespitum arigonis (Schmidt, 1853), a species of mollusc important in the epidemiology of dicro coeliosis in Spain, has been studied.
Abstract: The larval development of Dicrocoelium dendriticum (Digenea: Dicrocoeliidae) in experimentally infected Cernuella (Xeromagna) cespitum arigonis (Schmidt, 1853), a species of mollusc important in the epidemiology of dicrocoeliosis in Spain, has been studied. A total of 948 specimens of this mollusc, distributed in five batches, were tested with individual doses of 50 to 150 parasite eggs, obtained from sheep, after 4 days without food. After infection these molluscs and control specimens were kept in an environmental simulation chamber at 20 degrees C, 50% relative humidity and 7 h of light per day. To detect the parasite, a minimum of six molluscs were examined every 20 days from day 1 post-infection (p.i.). The eggs of D. dendriticum were eliminated in the molluscan faeces 48 h post infection. The percentages of molluscs harbouring the parasite ranged between 17.53% and 75%. Daughter sporocysts with undifferentiated germinal masses and occupying very reduced areas of the hepatopancreas were observed 50 days p.i. and in the period immediately following. After 110 days p.i. sporocysts with cercariae at different stages of development were found although slimeball emission was never observed.
TL;DR: Introduction of excretory/secretory products of both infective-stage and newborn larvae of Trichinella spiralis into cultures of primary rat myocytes elicited morphological and structural changes in the myotubes that showed the formation of 'nodular' structures, each bearing an enlarged nucleus, along theMyotubes.
Abstract: Introduction of excretory/secretory (ES) products of both infective-stage and newborn larvae of Trichinella spiralis into cultures of primary rat myocytes elicited morphological and structural changes in the myotubes. They appeared more granular, thinner, and failed to form networks. The most prominent lesion was the formation of ‘nodular’ structures, each bearing an enlarged nucleus, along the myotubes. Each node contained numerous cavities enclosed by an intact sarcolemma. Co-culture of myocytes with newborn larvae also elicited nodular formation but each node contained a large central cavity encircled by smaller ones. An immunocytolocalization study using IFAT and laser confocal microscopy showed the presence of parasitic epitopes inside the nodes. However, ES products from adult worms did not affect the myotubes.
TL;DR: The prosobranch snail Clypeomorus bifasciata in Kuwait Bay was examined for digenean infections over a one year period during 1994/1995 and the crab Xantho exaratus collected from snail sampling sites was heavily parasitized by microphallid metacercariae of the genera Longiductotrema and Microphallus.
Abstract: The prosobranch snail Clypeomorus bifasciata in Kuwait Bay was examined for digenean infections over a one year period during 1994/1995. A total of 1500 snails was examined and 567 (37.8%) were found to harbour nine digenean species. The prevalence of a microphallid species was 33.9% while each of the others occurred in less than 1.2% of the snails. The prevalence of infection increased with shell size. Multiple infections were observed in only five of the infected snails and the microphallid was involved in all of them. Snails were infected with the microphallid throughout the year and there appeared to be two peaks in the proportion of infected snails shedding cercariae, a winter peak from November to January and a summer peak from June to August. The crab Xantho exaratus collected from snail sampling sites was heavily parasitized by microphallid metacercariae of the genera Longiductotrema and Microphallus. This is the first report on microphallid metacercariae in crabs in the Arabian Gulf region.
TL;DR: The surface morphology of metacercariae isolated from Puntius spp.
Abstract: The surface morphology of metacercariae isolated from Puntius spp., adult worms from infected hamsters and eggs of Centrocestus formosanus (Digenea: Heterophyidae) were studied using scanning electron microscopy. It was found that the surfaces of the metacercariae and adult worms were closely similar in appearance. The oral sucker was surrounded by a circumoral expansion with two rows of 32 spines (16 spines each). The ventral sucker, with six large nonciliated papillae on the lip, and the genital opening were located mid-ventrally. The excretory pore was terminal. The body surface was covered with pectinate scale-like spines of varying sizes. The scales in the middle area were larger than those in the anterior and posterior parts of the body. Sensory papillae, mostly uniciliated, were present in greater abundance at the anterior region of both stages. However, morphological variations were observed among the adults depending on the age of the worms. At 4 weeks, the oral sucker and circumoral expansion were cobblestone-like in structure and the grooves of spines split compared with their smooth surfaces at 10 days. In addition, the ventral sucker became depressed and its large papillae on the lip disappeared at 10 weeks post infection. Multiciliated papillae were also present in 10-week old worms. Each egg of this parasite possessed a prominent operculum and a latticed design on the egg shell.
TL;DR: Comparison and statistical analysis of the results established that the species from Northern Ireland was M. piriformes and not M. pygmaeus as had previously been assumed, and indicates the need for critical assessment of the accuracy of literature dealing with the occurrence of 'M. pyGmaeus' in both intermediate and final hosts.
Abstract: This study compares the metacercariae of a ‘pygmaeus’ microphallid discovered in Littorina saxatilis from the coast of Northern Ireland with the metacercariae of Microphallus piriformes and M. pygmaeus from the same species of gastropod mollusc from Arctic Russia. Light and scanning electron microscopy were used to provide morphometric and surface details for descriptions of the organisms concerned. Comparison and statistical analysis of the results established that the species from Northern Ireland was M. piriformes and not M. pygmaeus as had previously been assumed. It dearly indicates the need for critical assessment of the accuracy of literature dealing with the occurrence of ‘M. pygmaeus’ in both intermediate and final hosts.