Showing papers in "Parasite in 2008"

Aedes albopictus, vecteur des virus du chikungunya et de la dengue à la Réunion : biologie et contrôle

Abstract: Chikungunya virus (CHIKV) and dengue virus (DENV) are mosquito-borne viruses transmitted by the Aedes genus. Dengue is considered as the most important arbovirus disease throughout the World. Chikungunya, known from epidemics in continental Africa and Asia, has up to now been poorly studied. It has been recently responsible for the severe 2004-2007 epidemic reported in the Indian Ocean (IO), which has caused several serious health and economic problems. This unprecedented epidemic of the IO has shown severe health troubles with morbidity and death associated, which had never been observed before. The two major vectors of those arboviruses in the IO area are Aedes aegypti and Aedes albopictus. The latest is considered as the main vector in most of the islands of the area, especially in Reunion Island. Ae. albopictus showed strong ecological plasticity. Small disposable containers were the principal urban breeding sites, and preferred natural developmental sites were bamboo stumps and rock holes in peri-urban and gully areas. The virus has been isolated from field collected Ae. albopictus females, and in two out of 500 pools of larvae, demonstrating vertical transmission. Experimental works showed that both Ae. albopictus and Ae. aegypti from west IO islands are efficient vectors of dengue and chikungunya viruses. Since 2006 and all along the epidemic of CHIKV, measures for the control of larvae (temephos then Bacillus thuringiensis) and adults (fenitrothion, then deltamethrine) of Ae. albopictus where applied along with individual and collective actions (by the use of repellents, and removal of breeding sites around houses) in Reunion Island. In order to prevent such epidemics, a preventive plan for arboviruses upsurge is ongoing processed. This plan would allow a quicker response to the threat and adapt it according to the virus and its specific vector.

Enterocytozoon bieneusi in human and animals, focus on laboratory identification and molecular epidemiology.

Abstract: Human microsporidian infections have emerged following the onset of the AIDS pandemic. Microsporidia are unicellular eukaryotic parasites that form spores. They are an exceptionally diverse group of parasites that infect a wide range of eukaryotic cells in numerous invertebrate and vertebrate hosts. Of the 14 species newly described as pathogens in human, Enterocytozoon bieneusi, which causes gastrointestinal diseases, is the most common agent of human infections. In the past fifteen years, E. bieneusi was also identified in environmental sources, especially in surface water, as well as in wild, domestic and farm animals. These findings raised concerns for waterborne, foodborne and zoonotic transmission. Molecular analyses of the 243-bp internal Transcribed spacer-(ITS) of the rRNA gene have revealed a considerable genetic variation within E. bieneusi isolates of human and animal origins, supporting the potential for zoonotic transmission. The focus of this revue is to present and discuss recent advances in diagnosis and zoonotic potential of E. bieneusi infections.

Toxoplasma gondii, "new" genotypes and virulence.

Abstract: Summary: Toxoplasma gondii has been described as a parasite with a low genetic diversity and a clonal population structure. The three main clonal lineages designated as type I, II or III largely predominate in Europe and North America. But strains not related to these main lineages circulate, notably, in other continents. They possess a shuffled combination of alleles that typify the three clonal types and unique polymorphisms detected by multilocus analysis. The population structure of Toxoplasma in these continents is also characterized by a higher genetic diversity associated with a lower linkage desequilibrium suggesting a role for genetic exchange. Due to their genomic diversity, it is difficult to draw global conclusions about their virulence. However, most of them are virulent in mice at isolation. Several reports also suggest a higher pathogenicity in humans and an association with ocular toxoplasmosis or severe cases of acquired toxoplasmosis in immunocompetent patients.

Environmental parasitology. Interactions between parasites and pollutants in the aquatic environment.

Abstract: In recent years there has been an increasing number of papers showing how parasitism and pollution can interact with each other in aquatic organisms. Among the variety of investigated aspects especially the combined effects of pollution and simultaneous infection on the health of aquatic hosts (molluscs, crustaceans, fish, mammals) is of considerable interest. Effects of pollution on the occurrence and distribution of parasites is another interesting field of "Environmental Parasitology" attracting increasing attention. This mini-review presents some promising examples of interdisciplinary studies paying attention to the fact that under natural conditions no organism will only be affected by either parasites or pollution.

Pathophysiology of enteric infections with Giardia duodenalius.

Abstract: Giardia is the most prevalent human intestinal parasitic protist in the world, and one of the most common parasite of companion animals and young livestock. Giardia is a major cause of diarrhea in children and in travelers. The host-microbial interactions that govern the outcome of infection remain incompletely understood. Findings available to date indicate that the infection causes diarrhea via a combination of intestinal malabsorption and hypersecretion. Malabsorption and maldigestion mainly result from a diffuse shortening of epithelial microvilli. This enterocytic injury is mediated by activated host T lymphocytes. Pathophysiological activation of lymphocytes is secondary to Giardia-induced disruption of epithelial tight junctions, which in turn increases intestinal permeability. Loss of epithelial barrier function is a result of Giardia-induced enterocyte apoptosis. Recent findings suggest that these effects may facilitate the development of chronic enteric disorders, including inflammatory bowel disease, irritable bowel syndrome, and allergies, via mechanisms that remain poorly understood. A newly discovered SGLT-1 glucose uptake-mediated host cytoprotective mechanism may represent an effective modulator of the epithelial apoptosis induced by this parasite, and, possibly, by other enteropathogens. A better understanding of the pathogenesis of giardiasis will shed light on new potential therapeutic targets.

Borrelia burgdorferi sensu lato, the agent of lyme borreliosis: life in the wilds.

Abstract: In Europe, Borrelia burgdorferi sensu lato (sl) the agent of Lyme borreliosis circulates in endemic areas between Ixodes ricinus ticks and a large number of vertebrate hosts upon which ticks feed. Currently, at least 12 different Borrelia species belonging to the complex B. burgdorferi sl have been identified among which seven have been detected in I. ricinus: B. burgdorferi sensu stricto (ss), B. garinii, B. afzelii, B. valaisiana, B. spielmanii and B. bissettii. A few dozens of vertebrate hosts have been identified as reservoirs for these Borrelia species. Specific associations were rather early observed between hosts, ticks and borrelia species, like for example between rodents and B. afzelii and B. burgdorferi ss, and between birds and B. garinii and B. valaisiana. The complement present in the blood of the hosts is the active component in the Borrelia host specificity. Recent studies confirmed trends toward specific association between Borrelia species and particular host, but also suggested that loose associations may be more frequent in transmission cycles in nature than previously thought.

Drug treatment and novel drug target against Cryptosporidium.

Abstract: Cryptosporidiosis emergence triggered the screening of many compounds for potential anti-cryptosporidial activity in which the majority were ineffective. The outbreak of cryptosporidiosis which occurred in Milwaukee in 1993 was not only the first significant emergence of Cryptosporidium spp. as a major human pathogen but also a huge waterborne outbreak thickening thousands of people from a major city in North America. Since then, outbreaks of cryptosporidiosis are regularly occurring throughout the world. New drugs against this parasite became consequently urgently needed. Among the most commonly used treatments against cryptosporidiosis are paromomycin, and azithromycin, which are partially effective. Nitazoxanide (NTZ)'s effectiveness was demonstrated in vitro, and in vivo using several animal models and finally in clinical trials. It significantly shortened the duration of diarrhea and decreased mortality in adults and in malnourished children. NTZ is not effective without an appropriate immune response. In AIDS patients, combination therapy restoring immunity along with antimicrobial treatment of Cryptosporidium infection is necessary. Recent investigations focused on the potential of molecular-based immunotherapy against this parasite. Others tested the effects of probiotic bacteria, but were unable to demonstrate eradication of C. parvum. New synthetic isoflavone derivatives demonstrated excellent activity against C. parvum in vitro and in a gerbil model of infection. Newly synthesized nitro- or non nitro- thiazolide compounds, derived from NTZ, have been recently shown to be at least as effective as NTZ against C. parvum in vitro development and are promising new therapeutic agents.

Plant-nematode interactions: environmental signals detected by the nematode's chemosensory organs control changes in the surface cuticle and behaviour.

Abstract: Plant parasitic nematodes have developed the capacity to sense and respond to chemical signals of host origin and the ability to orientate towards plant roots enhances the nematode's chance of survival. Root exudates contain a range of compounds which mediate belowground interactions with pathogenic and beneficial soil organisms. Chemical components of root exudates may deter one organism while attracting another and these compounds alter nematode behaviour and can either attract nematodes to the roots or result in repellence, motility inhibition or even death. In vitro, plant signals present in root exudates, trigger a rapid alteration of the surface cuticle of Meloidogyne incognita and the same changes were also induced by indole-acetic acid (IAA). IAA binds to the chemosensory organs of M. incognito and it is possible that IAA acts as a signal that orientates the nematode on the root surface in the rhizosphere and/or inside the root tissue and thereby promotes nematode infection.

The population genetic structure of vectors and our understanding of disease epidemiology.

Abstract: Understanding and predicting disease epidemiology relies on clear knowledge about the basic biology of the organisms involved. Despite the key role that arthropod vectors play in disease dynamics and detailed mechanistic work on the vector-pathogen interface, little information is often available about how these populations function under natural conditions. Population genetic studies can help fill this void by providing information about the taxonomic status of species, the spatial limits of populations, and the nature of gene flow among populations. Here, I briefly review different types of population genetic structure and some recent examples of where this information has provided key elements for understanding pathogen transmission in tick-borne systems.

Molecular dissection of host cell invasion by the apicomplexans: the glideosome

Abstract: Gliding motility is an essential and fascinating apicomplexan-typical adaptation to an intracellular lifestyle. Apicomplexan parasites rely on gliding motility for their migration across biological barriers and for host cell invasion and egress. This unusual substratedependent mode of locomotion involves the concerted action of secretory adhesins, a myosin motor, factors regulating actin dynamics and proteases. During invasion, complexes of soluble and transmembrane micronemes proteins (MICs) and rhoptry neck proteins (RONs) are discharged to the apical pole of the parasite, some protein acts as adhesins and bind to host cell receptors whereas others are involved in the moving junction formation. These complexes redistribute towards the posterior pole of the parasite via a physical connection to the parasite actomyosin system and are eventually released from the parasite surface by the action of parasite proteases.

Fish immune response to Myxozoan parasites.

Abstract: Myxozoan parasites are responsible for important economic losses among fisheries and aquaculture industries, and hence the high interest in studying the immune response of fish against them. The most important data available concerning the immune response of fish against myxosporeans are reviewed, with emphasis on the different innate and adaptive immune mechanisms, their relationship with natural and acquired resistance and the strategies to control and prevent myxosporoses. Cellular effectors (lymphocytes, granulocytes, phagocytes, non-specific cytotoxic cells, rodlet cells) and humoral factors (lysozyme, peroxidades, antiproteases, complement, specific antibodies) have been examined for several myxosporoses, and some immune relevant genes have been studied. This information will be crucial for the future development of vaccines and other preventive strategies such as immunomodulation and selection of disease-resistant strains

Infection of foxes by echinococcocus multilocularis in urban and suburban areas of nancy, france : influence of feeding habits and environment

Abstract: This study evaluated the impact of biological and environmental factors on the infection of red foxes (Vulpes vulpes) by Echinococcus multilocularis in an endemic area of north-east France. From January 2004 to April 2006, 127 foxes were examined for E. multilocularis and their stomach contents analysed. The effect of year, season, age, sex and urbanisation level on E. multilocularis presence was estimated using a General Linear Model (GLM) with logit link, (i.e. logistic regression). Urbanisation level was the only influencing factor, with a decreasing gradient from rural [54%, CI 95% (40-68)] to peri-urban [31%, CI 95% (15-52)] and urban area [4%, CI 95% (0.7-15)]. The consumption of Arvicola terrestris and Microtus sp., grassland species, the main presumed intermediate hosts of E. multilocularis, was studied by the same approach. The two species were consumed less in the urban area and more in autumn than in spring. Anthropogenic food consumption was linked to urbanisation and to age. The frequency of anthropogenic food consumption decreased in the rural area. A global model explaining the presence of E. multilocularis and including urbanisation level and diet was then elaborated. Independently of urbanisation, there was a suggestion of less E. multilocularis infection with anthropogenic food consumption. Red foxes consuming Microtus sp. and A. terrestris had higher worm burden than those that did not. The results suggest that the decreasing gradient observed from rural to urban area is linked to behaviour and feeding habits.

Parasite co-structure: broad and local scale approaches.

Abstract: A co-structure study is a comparison of demographic and/or genetic structure between two or more species. Such a comparative analysis among a parasite and its host(s) or among multiple parasite species is useful to elucidate factors that shape genetic variation within and among parasite populations. I provide a brief review of how co-structure studies in parasite systems can be used to address ecological, evolutionary, and epidemiological questions. Subjects that can be addressed with parasite costructure studies range from broad-scale analyses that compare phylogeographical patterns to local scale analyses that examine among host transmission within a host population.

Evaluation of circulating cathodic antigen (CCA) strip for diagnosis of urinary schistosomiasis in Hassoba school children, Afar, Ethiopia

Abstract: A total of 206 urine samples collected from Hassoba Elementary schoolchildren, Afar, Ethiopia, a low Schistosoma haematobium endemic setting, was diagnosed to evaluate the performance of CCA strip using double references, urine filtration technique and urinalysis dipstick (Combur 1.0 Test) that detect schistosome eggs and blood in urine, respectively. The former was used as a gold standard reference method. Sensitivity, specificity, positive and negative predictive values for the CCA were 52%, 63.8%, 56.7% and 59% respectively, with reference to urine filtration technique whereas these parameters were 50.4%, 62.4%, 55.6% and 57.5% respectively, with reference to Combur 10 Test. 47 S. haematobium egg-positive children were found negative by CCA strip while 38 egg-negative children were found positive by CCA strip. Moreover, among the pre-tests done in duplicate, inconsistent results were also recorded. Assays were also compared with regard to the cost of equipment and reagents, speed and simplicity of use. Though CCA strip was found to be rapid and could be performed with minimal training, it was found to be expensive (US $ 4.95 per test) to use it for large-scale field use even if its diagnostic value would have been satisfactory. Further development and standardization of the CCA strip are required for its applicability for field use. It is also recommended that its cost per strip should be substantially cut down if it is to be used in poor schistosomiasis endemic countries.

Seasonal and diurnal biting activities and zoonotic filarial infections of two Simulium species (Diptera: Simuliidae) in northern Thailand.

Abstract: Les rythmes journaliers et saisonniers d'activite de vol et de l'infection naturelle des simulies attirees par appât humain ont ete etudies dans le village de Ban Pang Faen, Province de Chiang Mai, nord de la Thailande. Les captures ont ete effectuees deux fois par mois de 6 heures a 18 h, de janvier 2005 a fevrier 2006. Parmi les dix especes de Simulium recoltees, S. nodosum et S. asakoae predominent, representant respectivement 57.3 % et 37.2 % des 16553 simulies femelles capturees. Ces deux especes montrent des schemas distincts d'abondance saisonniere : la majorite des S. nodosum (86.7 %) a ete recoltee a la saison chaude (de mi-fevrier a mi-maij, tandis que la majorite des S. asakoae (74.5 %) a ete recoltee pendant la saison des pluies (de mi-mai a mi-octobre). Pour l'activite journaliere de vol, S. nodosum presente deux courbes : la principale est unimodale avec un pic entre 17 h et 18 h; l'autre est bimodale avec un pic principal entre 16 h et 18 h et un pic mineur entre 7 h et 9 h. Chez S. asakoae, la courbe est principalement unimodale avec un pic entre 6 h et 10 h. Les larves de filaires recoltees chez S. nodosum et S. asakoae sont morphologiquement differentes. Les larves infectantes courtes et epaisses recoltees chez S. asakoae sont distinctes de toutes celles qui sont connues; il est suggere qu'elles pourraient etre des parasites d'oiseaux, Splendidofilariinae ou iemdaninae. L'infection de l'espece mammophile S. nodosum par de grandes larves infectantes de type Onchocerca est confirmee dans ce village. Les infections naturelles ont ete trouvees chaque mois (sauf en decembre) chez S. nodosum, ou chez S. asakoae, ou chez les deux. Les taux mensuels d'infection calcules avec tous les stades de filaires ont ete de 0,6-5,0 % pour S. nodosum et 1,0-4,0 % pour S. asakoae. Il est suggere que la population de ce village est exposee pendant toute l'annee au risque d'infection par des filaires zoonotiques.

Nosocomial Pneumocystis jirovecii infections.

Abstract: Airborne transmission of Pneumocystis sp. from host to host has been demonstrated in rodent models and several observations suggest that interindividual transmission occurs in humans. Moreover, it is accepted that the Pneumocystis organisms infecting each mammalian species are host specific and that the hypothesis of an animal reservoir for Pneumocystis jirovecii (P. jirovecii), the human-specific Pneumocystis species, can be excluded. An exosaprophytic form of the fungus cannot be strictly ruled out. However, these data point toward the potential for the specific host to serve as its own reservoir and for Pneumocystis infection in humans as an anthroponosis with humans as a reservoir for P. jirovecii. This review highlights the main data on host-to-host transmission of Pneumocystis in rodent models and in humans by the airborne route and provides a rationale for considering the occurrence of nosocomial infections and measures for their prevention.

Pcr-based methods to the diagnosis of imported malaria

Abstract: Rapid and precise diagnosis of malaria is needed to take care febrile patient returning from endemic areas. Since the first description of the diagnosis of Plasmodium infection by polymerase-chain-reaction (PCR), the role of this kind of molecular method in the laboratory diagnosis of imported malaria is still a topical question. PCR-based assays were found to be more sensitive and more specific than all conventional methods. The highest contribution of the molecular diagnosis is that a PCR negative result would ascertain the lack of any malaria infection, thus quickly orienting the investigations toward other aetiology. This technique should be now considered as the gold standard for the diagnosis of imported malaria.

Insulin receptors and glucose uptake in the human parasite Schistosoma mansoni.

Abstract: Very little is known about insulin signalling in schistosomes despite its potential importance in host-parasite molecular dialogue and parasite growth and development. The recent characterization of two insulin receptors (SmIR-1 and SmIR-2) in Schistosoma mansoni has led us to reconsider the question of the potential importance of insulin in host-schistosome interactions. In this work, we demonstrated that insulin could regulate glucose uptake in schistosomes and we investigated the implication of SmIR-1 and SmIR-2 in this process. The possibility that specific inhibitors of SmIR-1 and SmIR-2 tyrosine kinase activities could be developed to target schistosomes is discussed.

Population genetics of fungal diseases of plants

Abstract: Summary: Although parasitism is one of the most common lifestyles among eukaryotes, population genetics on parasites lag far behind those on free-living organisms. Yet, the advent of molecular markers offers great tools for studying important processes, such as dispersal, mating systems, adaptation to host and speciation. Here we highlight some studies that used molecular markers to address questions about the population genetics of fungal (including oomycetes) plant pathogens. We conclude that population genetics approaches have provided tremendous insights into the biology of a few fungal parasites and warrant more wide use in phytopathology. However, theoretical advances are badly needed to best apply the existing methods. Fungi are of prime interest not only because they are major parasites of plants and animals, but they also constitute tractable and highly useful models for understanding evolutionary processes. We hope that the emerging field of fungal evolution will attract more evolutionary biologists in the near future.

Kinetoplastid phylogenetics, with special reference to the evolution of parasitic trypanosomes.

Abstract: To fully understand the evolutionary history of parasitic kinetoplastids and to understand the context within which the evolution of each parasite group has developed, an understanding not just of the parasites, but of all kinetoplastids is required. Accordingly, this paper provides an overview of kineloplastid evolution and systematics, including coverage of the proposal by Moreira et al. (2004) to divide kinetoplasts into Prokinetoplastina (Ichthyobodo and Perkinsiella) and Metakinetoplastina luther bodonids and trypanosomatids|. The implications of such a revision, with regard to correctly identifying outgroup taxa for studies of evolution within taxa of medical importance, are addressed, together with a more detailed review of the evolution and origins of the trypanosomes in the light of new phylogenies, new approaches and revisions in kinetoplaslid systematics.

The nematoda Filarioidea: critical analysis linking molecular and traditional approaches.

Abstract: Summary: The molecular analysis of the Filarioidea and the endobacteria Wolbachia is no more limited to the agents of human diseases and the diversified sampling permits a synthesis with the morphological and biological results. The validity of the genera with “uncoherent host range”, such as Mansonella, Litomosoides and Cercopithifilaria, is confirmed and, consequently, their evolution by host-switchings. Dirofilaria and Onchocerca, types of two subfamilies, appear more closely related than with other onchocercids. Waltonellinae from anurans and Oswaldofilariinae from reptiles have a basal position. These filariae, and some others also considered primitive, do not harbour Wolbachia. Evidence for transversal transmission of the bacteria and a second acquisition event is given with the supergroup F, identified in Mansonella, in one of the Cercopithifilaria species and in arthropods.

Kinetoplastida: new therapeutic strategies

Abstract: New formulations and therapeutic switching of the established drugs, amphotericin B and paromomycin, together with the discovery of miltefosine, have significantly improved the opportunities for treatment of visceral leishmaniasis (VL) chemotherapy. However, for human African trypanosomiasis (HAT), Chagas disease and cutaneous leishmaniases there has been limited progress. For HAT, a novel diamidine, parfuramidine, is in phase III clinical trial for early-stage disease, but for the treatment of late-stage disease there are no new drugs and combinations of eflornithine with melarsoprol or nifurtimox have been the focus of clinical studies. For Chagas disease, different classes of compounds that have validated biochemical targets, sterol biosynthesis methylases and cysteine proteases, are in various stages of development. The genome sequences that are now available for the pathogens that cause the leishmaniases and trypanosomiases, and new methods for rapid validation of targets, are part of the solution to discover new drugs. The integration of medicinal chemistry, pharmacokinetics, project planning and interaction with the pharma/biotech sector are essential if progress is to be made. Although there are financial constraints, the appearance of new funding sources and not-for-profit product development partnerships offers hope for drug development.

Platyhelminth systematics and the emergence of new characters.

Abstract: Since the inclusion of molecular data in modern phylogenetic analyses, significant progress in resolving the origins and radiation of flatworms has been made, although some key problems remain. Here I review developments in the supply and use of systematic characters that provide the basis for diagnosis and phylogeny reconstruction, that in turn have driven systematic revisions and the interpretation of broader evolutionary patterns and processes; focus is placed on the parasitic taxa. Although useful tools have been refined to the point of becoming established systematic markers of broad utility, attention to the need for denser gene and taxon sampling is addressed in the light of unresolved questions and current trends in molecular systematics, from nucleotide to genome. Tradition and the nature of available comparative information tends to dictate the choice of systematic markers, but faced with incongruent phylogenies, the emergence of new technologies and the need for rapid species diagnosis, there is a pressing need to assess and standardize our choice of tools so they are fit for purpose, available to all and used widely. I present a brief review of existing and potential sources of phylogenetic characters and discuss their likely value in the context of the systematics and diagnostics of parasitic flatworms.

The influence of host hormones and cytokines on Echinococcus multilocularis signalling and development.

Abstract: Parasitic helminths display highly complex life-cycles in which the establishment of adults or larvae within host target organs as well as the transition of one developmental stage to the following is influenced by host-derived factors. Due to its approachability concerning in vitro cultivation, the larval stage of the fox-tapeworm Echinococcus multilocularis has recently emerged as a model system to study the molecular nature of such host-derived stimuli and their influence on developmental control in the parasite. Data obtained so far indicate that cytokines which are used by the host for cell-cell communication can also be exploited by the parasite as clues to find suitable target organs. This involves direct interactions of evolutionary conserved signalling systems of the receptor tyrosine--and the receptor serine/threonine-kinase pathways of the parasite with corresponding host cytokines of the insulin-, the epidermal growth factor-, and the transforming growth factor-beta-families. In the present article, we will briefly review in vitro cultivation approaches undertaken so far for E. multilocularis larvae as well as our current knowledge on the parasite's signalling systems and their interaction with host cytokines.

Field-based evaluation of a reagent strip test for diagnosis of schistosomiasis mansoni by detecting circulating cathodic antigen (CCA) in urine in low endemic area in Ethiopia.

Abstract: The sensitivity specificity positive and negative predictive values of a reagent strip test for the diagnosis of schistosomiasis mansoni by detecting circulating cathodic antigen (CCA) in urine were evaluated using 184 stool and urine samples collected from schoolchildren living in relatively low endemic area of schistosomiasis mansoni in Ethiopia. A combined result of stool samples processed by Kato and formol-ether concentration methods was used as gold standard. The results showed that detection of CCA in urine using reagent strip test was slightly higher than the combined results of the stool techniques (65.2 % vs 42.4 % p > 0.05) in suggesting the prevalence of the disease. The sensitivity specificity positive and negative predictive values of the reagent strip test were 76.9 % 43.4 % 50 % and 71.9 % respectively. The result of egg counts using Kato method suggested that detection of urine CCA could be used to indicate the intensity of infection. Nevertheless like that of stool examination the reagent strip test was found to be less sensitive in case of light to moderate infections. About 23.1 % of the study children who were excreting the eggs of the parasite were found negative by the reagent strip test. The relative insensitivity of a reagent strip test in low intensity of infection necessitates for the development of more sensitive assay that can truly discriminate schistosome-infected from non-infected individuals.

Infective larvae of five Onchocerca species from experimentally infected Simulium species in an area of zoonotic onchocerciasis in Japan.

Abstract: Microfilariae of five Onchocerca species, O. dewittei japonica (the causative agent of zoonotic onchocerciasis in Oita, Kyushu, Japan) from wild boar (Sus scrofa), O. skrjabini and O. eberhardi from sika deer (Cenus nippon), O. tienalis from cattle, and an as yet unnamed Onchocerca sp. from wild boar, were injected intrathoracically into newly-emerged black flies of several species from Oita to search the potential vector(s) of these parasites and identify their infective larvae. Development of O. dewittei japonica microfilariae to the infective larvae occurred in Simulium aokii, S. arakowae, S. bidentatum, S. japonicum, S. quinquestriatum, and S. rufibasis while development of infective larvae of O. skrjabini, O. eberhardi, and the unnamed Onchocerca sp. was observed in S. aokii, S. arakawae, and S. bidentatum. Development of O. lienalis microfilaria to infective larvae occurred in S. arakawae. Based on the morphology of infective larvae obtained, we proposed a key of identification of Onchocerca infective larvae found in Oita. We also reconsider the identification of three types of infective larvae previously recovered from Simulium species captured at cattle sheds: the large type I larvae that may be an undescribed species; the small type III identified as O. lienalis may include O. skrjabini too; the intermediary type II that may be O. gutturosa, or O. dewittei japonica, or the unnamed Onchocerca sp. of wild boar.

Use of nuclear and mitochondrial DNA PCR and sequencing for molecular identification of Diphyllobothrium isolates potentially infective for humans.

Abstract: Tapeworms of the genus Diphyllobothrium (Cobold, 1858) are widely distributed all around the world and some of them are agents of human diphyllobothriasis. Approximately 50 species have been described within the Diphyllobothrium genus but only 13 are human pathogens. Species identification by using morphological criteria is very difficult. We determined the value of 18S ribosomal RNA gene, internal transcribed spacer (ITS) and cytochrome c oxidase subunit 1 gene (COI) sequences to differentiate between Diphyllobothrium isolates. Sequences from 18 isolates (larvae or adults) of D. latum, D. nihonkaiense, D. ditremum, D. dentriticum and D. stemmacephalum species were obtained. COI region sequences analysis was clearly more discriminative than those of the ITS1 and 18S rRNA and was a useful tool for identifying specimens.

The inflammatory response of fish to helminth parasites

Abstract: Fish serve as a good model for studying vertebrate immune systems because they have a relatively simple system. Descriptions of histopathological effects of helminth parasites on fish are few and far between with limited observations made on the identification of the inflammatory cells involved in the host reaction. Recently, two cell types found within teleosts received a great deal of attention, namely mast cells and rodlet cells. Fish most cells also known as eosinophilic granule cells, are morphologically and functionally similar to their mammalian counterparts. Acute tissue damage causes mast cells degranulation and the release of mediators of inflammation, whereas, an increase in the number of these cells is usually found in chronically inflamed tissues. Rodlet cells, however, are exclusive to fish and are characterized by a distinct cell cortex and conspicuous inclusions, called rodlets, which accounts for their name. Piscidin has also been encountered within rodlet cells. As important cell types within the immune system of fish, both mast cells and rodlet cells have been seen to increase in number in infected fish, notably at the sites of pathogen attachment or infection. The present survey will provide data from studies with the light microscope on the response of mast cells and rodlet cells in a range of fish species (Anguilla anguilla, Oncorhynchus mykiss, Salmo trutta, Coregonus lavoretus) infected with a range of different parasite genera including representatives from the Digenea, Cestoda, Nematoda and Acanthocephala.

Molecular crosstalks in Leishmania-sandfly-host relationships.

Abstract: Sandflies (Diptera: Phlebotominael are vectors of Leishmania parasites, causative agents of important human and animal diseases with diverse manifestations. This review summarizes present knowledge about the vectorial part of Leishmania life cycle and parasite transmission to the vertebrate host. Particularly, it focuses on molecules that determine the establishment of parasite infection in sandfly midgut. It describes the concept of specific versus permissive sandfly vectors, explains the epidemiological consequences of broad susceptibility of permissive sandflies and demonstrates that genetic exchange may positively affect Leishmania fitness in the vector. Last but not least, the review describes recent knowledge about circulating antibodies produced by hosts in response to sandfly bites. Studies on specificity and kinetics of antibody response revealed that anti-saliva IgG could be used as a marker of host exposure to sandflies, i.e. as a useful tool for evaluation of vector control.

Genetic relationships among species of Contracaecum Railliet & Henry, 1912 and Phocascaris Höst, 1932 (Nematoda: Anisakidae) from pinnipeds inferred from mitochondrial cox2 sequences, and congruence with allozyme data.

Abstract: The genetic relationships among 11 taxa, belonging to the genus Contracaecum (C. osculatum A, C. osculatum B, C. osculatum (s.s.), C. osculatum D, C. osculatum E, C. osculatum baicalensis, C. mirounga, C. radiatum, C. ogmorhini (s.s.), C. margolisi) and Phocascoris (Phocoscris cystophorae), parasites as adults of seals, were inferred from sequence analysis 1519 bp) of the mitochondrial cytochrome c oxidase subunit II (mtDNA cox2) gene. Phylogenetic analyses obtained from Parsimony (MP) and Neighbour-Joining (NJ) K2P distance values generated similar topologies, each well supported at major nodes. All analyses delineated two main clades: the first encompassing the parasites of the phocid seals, i.e. the C. osculatum species complex, C. osculatum boicolensis, C. mirounga and C. radiatum, with the latter two species forming a separate subclade; the second including the parasites of otarids, i.e. C. ogmorhini (s.s.) and C. margolisi. An overall high congruence between mtDNA inferred tree topologies and those produced from nuclear data sets (20 allozyme loci) was observed. Comparison of the phylogenetic hypothesis here produced for Controcaecum spp. plus Phocascaris with those currently available for their definitive hosts (pinnipeds) suggests parallelism between hosts and parasite phylogenetic tree topologies.