| rats and bilharziasis in guadeloupe. | the rats in guadeloupe (rattus rattus and rattus norvegicus) may play a part in schistosomiasis in three ways: - by harbouring fertile s. mansoni, a fact which serves to increase the total population of the parasite and may eventually take part in the infestation of man; - by harbouring a great number of ribeiroia marini, a trematode whose larval stages sterilize biomphalaria glabrata, the vector of schistosomiasis; - simply by eating b. glabrata. the quantitative influence of these contradicto ... | 1975 | 7114 |
| [permissivity of the rat (rattus rattus) of guadeloupe with regard to schistosoma mansoni and evidence for migration of adult schistosomes to the lungs]. | in contrast to the laboratory rat, the rat (rattus rattus) of guadeloupe is a favorable host for the life cycle of s. mansoni: the parasite population is maintained at a high level (between 8 and 16% in this host until the 16th week and reproduces normally). the evolution of the parasitose is marked, shortly after the 8th week, by a transfer of schistosomes from the liver to the lungs. | 1978 | 96960 |
| [aspects of rats schistosomiasis in the non-salted mangrove swamps and the backmangrove area in the island of grande-terre (guadeloupe) (author's transl)]. | the study of parasitism by schistosoma mansoni among rats (rattus rattus and rattus norvegicus) has been carried on in guadeloupe. over half the rats caught in the non-salted mangrove swamps and the back-mangrove area of the island of grande-terre are parasitized. it seems possible diagrammatize the characteristics of these sites, where the cycle of rats schistosomiasis develops. | 1977 | 613965 |
| [the role of the rat in the dynamics of endemic schistosomias in guadeloupe]. | in guadeloupe (french lesser antilles), because they are simultaneously infested with schistosoma mansoni, which causes the human intestinal schistosomiasis, and ribeiroia marini, a trematode which sterilizes the mollusk-host of the schistosoma, the rats (rattus rattus and rattus norvegicus) seem able to influence, at least locally, the infestation of the human population. | 1975 | 813876 |
| [variations in the immune response in several schistosome-rat infections]. | the evolution of immunological reactions in two rat strains, namely rattus rattus from guadeloupe and rattus norvegicus var. albinos, was studied. both have beem experimentally infested by three different strains of schistosoma mansoni. we observed that rattus rattus infested by the american strains reacts poorly and shows a persistant infection contrary to the results obtained with other infestations. so it appears that a special pathogenic complex might be present in guadeloupe which could exp ... | 1976 | 825253 |
| long-term dynamics of natural populations of schistosoma mansoni among rattus rattus in patchy environment. | dynamics of natural populations of schistosoma mansoni were studied during 8 consecutive years among rattus rattus populations from 8 transmission sites of the marshy forest focus of guadeloupe (french west indies). the schistosome population is over-dispersed (k = 0.119) within the murine hosts and ecological factors linked to the patchy environment may be responsible for such aggregated distribution. analysis of the spatio-temporal variations in prevalences, intensities and abundances showed l ... | 1992 | 1594292 |
| relocation of schistosoma mansoni in the lungs and resistance to reinfection in rattus rattus. | the localization of adult schistosoma mansoni originating from guadeloupe (west indies) was analysed in the natural host rattus rattus in experimental and natural infections. a transfer of schistosomes from the porto-mesenteric system to the lungs occurs between the 4th and the 20th weeks post-infection, with a peak between 4 and 8 weeks; it should be noted that the worms start laying eggs at 4 weeks post-infection. in both experimentally and naturally infected r. rattus the relocation of schist ... | 1992 | 1614740 |
| [experimental study of the permissivity of the wild rat (rattus rattus) of guadeloupe with regard to schistosoma mansoni. hypothesis on the role of this host in the dynamics of natural habitats (author's transl)]. | unlike the white laboratory rat, the wild rat (rattus rattus) of guadeloupe behaves as a permissive host with regard to schistosoma mansoni, at least during a certain number of successive passages. the study of the host-parasite relationship of this couple has enabled us to demonstrate a certain number of fundamental differences in relation to the data furnished by the white rat; the worm recovery rate tested in the 4th week is more than twice as high as in the white rat (32% vs 11%), the "self ... | 1980 | 6104424 |
| [migration of schistosoma mansoni adults in rattus rattus from the mesenteric vein systems to the lungs]. | the possibility of a contribution of rattus rattus to the maintenance of intestinal schistosomiasis foci has recently been suggested. in this rodent, adult schistosoma mansoni carry out an internal migration. this begins at the 4th week and finishes at the 9th week after infection. the migration from the mesenteric veins to the liver, then from the liver to the lungs, takes place via blood vessels. schistosomes, some of which remain paired, pass successively along the portal vein, the hepatic ve ... | 1980 | 6771052 |
| [evaluation of 10 years of research on s. mansoni schistosomiasis a in the french west indies]. | from 1971 until 1982, we studied the ecological factors which stead fast a perennial schistosomiasis in guadeloupe on an exhaustive mode. more recently, we start a similar investigation in martinique. in guadeloupe the single vector of schistosoma mansoni is the snail biomphalaria glabrata which is an ubiquist species. but the transmission to man is restricted to the "canal-sewers" where faeces are dropped and not in the rivers of basse-terre or the ponds of grande-terre. moreover, the infection ... | 1982 | 7126776 |
| [experimental approach of the role of rattus rattus and rattus norvegicus in the focus of schistosoma mansoni of guadeloupe. comparative development of s. mansoni in 2 natural hosts (r. rattus and r. norvegicus) and 2 laboratory hosts (the white mouse and the white rat)]. | we have studied the development of schistosoma mansoni in two natural hosts, rattus rattus and rattus norvegicus, and in two laboratory hosts, the white mouse and the white rat. the study of survival shows that the percentage of cercariae recovered as adult worms four weeks after exposure is 31% in r. rattus, 27% in the white mouse, 14% in the laboratory rat and 12% in r. norvegicus. twenty weeks after exposure, 62% of the schistosomes which were present four weeks after exposure are still alive ... | 1982 | 7137802 |
| infectivity in rodents of schistosoma mansoni cercariae of human and murine origin. | experimental infections of white laboratory mice and wild rats (rattus rattus) with cercariae of schistosoma mansoni of different descent, whether murine or human, demonstrate that there is no significant difference in the probability of maturation of these cercariae into adult schistosomes. these results enable us to hypothesize that the reverse would be true, i.e. that cercariae of murine or human descent would be capable of infecting man with the same success rate. circulation of the parasite ... | 1980 | 7217645 |
| [the "cercarial index" of schistosoma mansoni. epidemiological and experimental results (author's transl)]. | the cercarial index defined by bayssade-dufour (1977) differs according to the hosts in which schistosoma mansoni is cycled. this index is close to 1 in african human strains, 1.3 in carribbean human strains, and 1.6 in strains kept for a number of years in rodents. the first epidemiological and experimental results supported the argument that the transmission of intestinal bilharzia in the mountainous refuge of infection at grand-etang, guadeloup, is maintained exclusively by murine rodents. ne ... | 1981 | 7325525 |
| experimental host-induced selection in schistosoma mansoni strains from guadeloupe and comparison with natural observations. | allelic frequency variation at the malate dehydrogenase (e.c.1.1.1.37) polymorphic locus (mdh-1) was analysed during several successive generations in four strains of schistosoma mansoni from guadeloupe, maintained experimentally on mice. a rapid evolution of the frequency of the mdh-1a allele is interpreted as being the result of an interaction between experimental drift and selection induced by the murine laboratory host. these experimental results are compared to the genetic structures observ ... | 1993 | 8432659 |
| distribution of schistosome genetic diversity within naturally infected rattus rattus detected by rapd markers. | random amplified polymorphic dna markers (rapd) were used to visualize the genetic diversity within and between infrapopulations of schistosoma mansoni recovered from the natural vertebrate host, rattus rattus, trapped at an insular guadeloupean focus. phenotypes were characterized by the sex of the parasites and by 8 polymorphic markers generated by 3 primers. among the 212 parasite individuals recovered from 10 infected rats, 78 genotypes were characterized. all the hosts naturally infected ha ... | 1996 | 8939047 |
| natural schistosoma mansoni infection in wild rats from guadeloupe: parasitological and immunological aspects. | rattus rattus is the predominant rodent in the mangrove area of guadeloupe. between 1990 and 1991 we found 73 r. rattus and five r. norvegicus. among the infected rats with schistosoma mansoni, 59% for r. rattus and 80% for r. norvegicus, the comparison of the median of the worm load was not statistically different. both species of infected rats showed adult worms and eggs in the lungs and 20% of them showed, at the same time, two and even three generations of worms. neither adults nor eggs were ... | 1997 | 9351999 |
| schistosome-induced portacaval haemodynamic changes in rattus rattus are associated with translocation of adult worms to the lungs. | the presence of naturally portacaval shunts has been investigated in the vasculature of normal and schistosoma mansoni-infected rattus rattus. using the technique of injecting polystyrene microspheres in the superior mesenteric vein, we demonstrated that the presence of adult schistosomes in the lungs of r. rattus was not due to an innate anomaly of the rat vasculature but resulted from the formation of portacaval shunts during infection. in rats harbouring a bisexual infection, microspheres wer ... | 1998 | 9550217 |
| population biology of schistosoma mansoni in the black rat: host regulation and basic transmission rate. | a simple mathematical model was built to investigate the population biology of schistosoma mansoni in its natural definitive host, the black rat (rattus rattus). prevalence and parasite abundance over 13 years from field studies and data from laboratory experiments were used to set up the model. sensitivity analysis showed that the abundance of parasites is strongly influenced by variation in the values of infection parameters. the model shows that the parasite is able to control populations of ... | 1999 | 10404261 |
| parasite (schistosoma mansoni) and host (biomphalaria glabrata) genetic diversity: population structure in a fragmented landscape. | random amplified polymorphic dna (rapd) markers were used to quantify genetic diversity within and between 5 populations of schistosoma mansoni within its definitive host (rattus rattus) and the 5 corresponding populations of the snail intermediate host (biomphalaria glabrata) from a limited endemic area of murine schistosomiasis on the island of guadeloupe. analysis of molecular variance (amova) and canonical correspondence analysis (cca) were used to test the significance of genetic differenti ... | 2001 | 11393828 |
| genetic diversity of schistosoma mansoni within and among individual hosts (rattus rattus): infrapopulation differentiation at microspatial scale. | the distribution of genetic diversity in a local population of the trematode schistosoma mansoni was determined within and between individual wild rats at a microspatial geographic scale of a standing water transmission site. using rapd markers, molecular variance and canonical correspondence analysis were performed to test the significance of genetic differentiation between infrapopulations. of total gene diversity, 8 and 11% was partitioned between hosts trapped at few metres distance from eac ... | 2001 | 11730788 |
| sex-specific genetic structure in schistosoma mansoni: evolutionary and epidemiological implications. | we studied the population genetic structure of 360 and 1247 adult schistosoma mansoni using seven microsatellite and seven random amplified polymorphic dna (rapd) markers, respectively. parasites were collected from their natural definitive host rattus rattus in guadeloupe (west indies). we found a sex-specific genetic structure, a pattern never before reported in a parasitic organism. male genotypes were more randomly distributed among rats than female genotypes. this interpretation was consist ... | 2002 | 12074730 |
| molecular ecology of schistosoma mansoni transmission inferred from the genetic composition of larval and adult infrapopulations within intermediate and definitive hosts. | we investigated the genotypic composition of the digenetic parasite schistosoma mansoni for its adult stages within the definitive host (the wild rat, rattus rattus) and for the larval stages within the intermediate host (the snail, biomphalaria glabrata) both collected at the same transmission site. our analyses are based upon the recognition and distribution of 200 different multilocus genotypes generated by rapd markers. while intramolluscan larval infrapopulations are characterized by a low ... | 2004 | 15552402 |
| dispersal in a parasitic worm and its two hosts: consequence for local adaptation. | characterizing host and parasite population genetic structure and estimating gene flow among populations is essential for understanding coevolutionary interactions between hosts and parasites. we examined the population genetic structure of the trematode schistosoma mansoni and its two host species (the definitive host rattus rattus and the intermediate host biomphalaria glabrata) using microsatellite markers. parasites were sampled from rats. the study was conducted in five sites of the guadelo ... | 2005 | 15807416 |
| f-statistics under alternation of sexual and asexual reproduction: a model and data from schistosomes (platyhelminth parasites). | accurate inferences on population genetics data require a sound underlying theoretical null model. nearly nothing is known about the gene dynamics of organisms with complex life cycles precluding any biological interpretation of population genetics parameters. in this article, we used an infinite island model to derive the expectations of those parameters for the life cycle of a dioecious organism obligatorily alternating sexual and asexual reproductions as it is the case for schistosomes (plath ... | 2005 | 15813776 |
| host sex and parasite genetic diversity. | is the genetic diversity of parasites infecting male and female hosts equal or different? this is the question we address in this paper by studying the neutral genetic variability of the plathyhelminth trematode schistosoma mansoni within males and females of its natural murine host rattus rattus in the marshy forest focus of guadeloupe (french west indies). using seven microsatellite markers, we demonstrate that parasites from male hosts are genetically more diversified than parasites from fema ... | 2006 | 16872857 |
| a new chronotype of schistosoma mansoni: adaptive significance. | to optimise host-to-host transmission, digenean trematodes (parasites) synchronize their cercarial emission patterns with the aquatic activities of their vertebrate hosts. schistosoma mansoni has a strictly diurnal shedding pattern involving two circadian chronotypes: an early shedding pattern with a mean peak occurring at 11:00 h and a late pattern with a mean peak occurring at 16:00 h. we analysed the cercarial emergence pattern of three schistosome populations from oman where s. mansoni is re ... | 2012 | 22512397 |
| [on the natural infection of domestic rats (rattus rattus) by schistosoma mansoni in central africa]. | | 1955 | 13250376 |
| schistosoma mansoni from naturally infected rattus rattus in guadeloupe: identification, prevalence and enzyme polymorphism. | an enzymatic comparison has been made between isolates of schistosoma mansoni from rats and humans in guadeloupe and a burundi isolate of s. rodhaini. analyses of ldh, mdh, acp, pgm, gpi, g6pdh and hk by isoelectric focusing provided no evidence for the involvement of s. rodhaini in the recent evolution of the schistosomes currently endemic in guadeloupe. no distinction could be made between murine and human isolates of s. mansoni and it is suggested that murine schistosomiasis should not theref ... | 1986 | 3092170 |
| schistosoma mansoni: comparison of a caribbean and african strain and experimental crossing based on compatibility with intermediate hosts and rattus rattus. | to elucidate changes relative to compatibility with intermediate and definitive hosts affecting schistosoma mansoni since it was introduced to the new world, the compatibility of s. mansoni from africa (the cameroons), from the caribbean (guadeloupe), and those resulting from experimental crosses with the gastropods biomphalaria glabrata and b. pfeifferi has been studied. results show that s. mansoni, regardless of its origin or its usual snail host, always infects b. pfeifferi more successfully ... | 1986 | 3082664 |
| [polymorphism of schistosoma mansoni eggs in the guadeloupe (french antilles) focus: presence of s. rodhaini-like parasites?]. | a comparative study of egg morphology of schistosoma mansoni carried out between 9 parasite populations from guadeloupean foci demonstrates the existence of an intraspecific polymorphism. three types of lateral spined eggs have been described and their relative proportions observed between populations are related to the participation of a wild host-reservoir (rattus rattus) in the life cycle of the parasite. eggs of schistosomes originating from urbanized foci where man plays the main role in th ... | 1986 | 2882660 |