| hybridization between different strains of schistosoma intercalatum fisher, 1934 from cameroun and zaïre. | the offspring from hybridization experiments between schistosoma intercalatum, cameroun (intermediate host bulinus forskalii) and s. intercalatum, zaïre (intermediate host b. globosus) was investigated. reciprocal crosses between the two forms were performed. f1- and f2-miracidia developed in both parental intermediate hosts. the minimum prepatent period was 24 days at 26 degrees c, an average of the prepatent periods for the two parental strains. the total cercariae production per 100 exposed s ... | 1978 | 659822 |
| investigations of the unimiracidial infection of schistosoma intercalatum in snails and the infection of the final host using cercariae of one sex. | infection with single miracidial doses of schistosoma intercalatum from cameroun in bulinus forskalii and from zaire in b.globosus resulted in an equal number of male and female infections. the cercarial production of both sexes started at the same time. the male infected snails produced a greater number of cercariae, because of the longer duration of infection. the recovery of schistosomes from infection with male and female cercariae was for s. intercalatum, zaire, 38.8 +/- 10.6 and 18.7 +/- 1 ... | 1977 | 864226 |
| [research of the life cycle of a paramphistomidae (trematoda) of amphibians in africa (author's transl)]. | the intermediate hosts of diplodiscus subclavatus are in togo, bulinus forskalii and segmentorbis kinisaensis. the cercariae, amphistome, leave soon the rediae to achieve their development at the top of the hepatopancreas of the mollusc. the usual infestation of the definitive host occurs by penetration of cercariae into tadpoles with the water flood. secondary ways of infestation keep up the prevalence near a high level. | 1977 | 900779 |
| host-parasite relationship of bulinus forskalii (ehrenberg) and schistosoma intercalatum fisher 1934, from cameroun. | the susceptibility of 13 different b. forskalii strains from zaire, cameroun, gabon, senegal, rhodesia and tanzania and b. reticulatus wrighti aden has been tested to infection with schistosoma intercalatum from cameroun. the most common prepatent period was 23-28 days. b. forskalii from zaire, cameroun and gabon were excellent intermediate hosts with infection rates varying from 59-0 to 97-4% and with very low death rates, 0-28-4%. the strains from senegal and rhodesia had infection rates from ... | 1975 | 1151052 |
| [remarks on the ecological adaptation of the snail aquatic fauna in saline medium of the dallol ponds. (republique du niger) (author's transl)]. | human vesical and intestinal bilharziasis, bovine fasciolosis and paramphistomosis, equine gastrodiscosis and ovine carmyeriosis, are frequent in the dallols'region, (12 degrees - 13 degrees 30 n. lat. ; 3 degrees e. long.), republique du niger, africa. dallols are fossil valleys pouring water from late saharian lakes. they are also tributaries of the niger river. during the dry season, they become dry and many residual ponds of varied dimensions; from tens feet to one or two miles long, are lyi ... | 1975 | 1221913 |
| [population dynamics and infestation of bulinus truncatus and bulinus forskalii by schistosomal larvae in the sudan-sahelian zone of cameroon]. | the evolution of the population densities of bulinus truncatus and bulinus forskalii has been studied during 18 months in a number of sites of the sudan-sahelian zone of cameroon, in relation to certain environmental factors. only the altitude of the water in the sites has an influence on the density of the snails. the populations of b. truncatus present a greater proportion of young molluscs during the entire year, with the exception of the last months of the dry season. the population dynamics ... | 1992 | 1292427 |
| a new focus of schistosoma haematobium/s. intercalatum hybrid in cameroon. | terminal-spined schistosome eggs were found in both stool and urine specimens of a high proportion of infected individuals in kinding njabi, a village located in a savannah/forest ecotone of center province, cameroon. infections with terminal-spined schistosomes are not common in that region and first appeared in kinding njabi in the mid-1980s. the village population, determined by house-to-house census in 1986, was 345. of 302 stool samples examined by a thick smear technique, 58 (19%) were pos ... | 1991 | 1928567 |
| [focus on schistosoma intercalatum]. | area of frequent occurrence of schistosoma intercalatum is limited to few countries along the guinea gulf although the main intervening agents, bulinus globosus, bulinus forskalii are dispersed all over africa. reservoir of schistosoma intercalatum is only human and its cycle is difficult to keep up in test animals. clinical manifestations are, the most often, a simultaneous inflammation of the rectum and sigmoid. diagnosis is based on the presence of ova with terminal spine in feces or in biops ... | 1990 | 2077322 |
| [epidemiological study of schistosomes in a coastal lake of recent formation]. | parasitological and malacological surveys were conducted round a fresh water lake, previously a salted lagoon, in the south of bénin and leaded to measure prevalence of schistosomiasis. 23 percent of population were found positive for schistosoma haematobium and 13.4 percent for s. mansoni. prevalences were different from locality to locality according to beach variations, but mean of parasite density was quite constant. males were significantly more infected than females and young adults were m ... | 1990 | 2126751 |
| urban epidemiology of schistosoma intercalatum in the city of bata, equatorial guinea. | in a cross sectional study, 1221 individuals were enrolled to determine the urban epidemiology of schistosoma intercalatum in the city of bata, equatorial guinea. bulinus forskalii was the only intermediate host for schistosomes found in the study areas. the only schistosoma species detected in faeces was s. intercalatum. however, no schistosoma eggs were found in urine. the overall prevalence of s. intercalatum infection was 21.2%. although infected subjects were found in all age groups, peak p ... | 1990 | 2255841 |
| genetic variability in the compatibility between schistosoma haematobium and its potential vectors in niger. epidemiological implications. | a populational study of the compatibility between schistosoma haematobium and its potential vectors has been carried out in the niger, confronting samples of s. haematobium populations from three epidemiologic foci with bulinus populations originating from the same focus (sympatric infection) and with bulinus populations from other foci (allopatric infections). the three transmission foci selected were irrigation canals in ricefields along the niger river where one finds: bulinus truncatus rohlf ... | 1990 | 2382092 |
| studies on schistosomiasis in the niger delta: schistosoma intercalatum in the urban city of port harcourt, nigeria. | ova of s. intercalatum have been found in the urban city of port harcourt in the niger delta area of nigeria, following examination of stool and urine samples from 1,709 persons (5-15 years of age) resident in various parts of the city. the ova occurred only in urine, with prevalence ranging from 1.0% to 9.8% with an overall prevalence of 5.7%. the intensity of the infection was low. most infected individuals had counts of less than 500 ova in total bladder content. there was no significant diff ... | 1989 | 2772131 |
| a study of the biological characteristics of a hybrid line between male schistosoma haematobium (dar es salaam, tanzania) and female s. intercalatum (edea, cameroun). | the viability of a hybrid between male schistosoma haematobium (dar es salaam, tanzania) and female s. intercalatum (edea, cameroun) was studied for up to the f7 hybrid generation and the biological characteristics of the hybrid were compared with those of each of the parental species. using the total cercarial production/100 exposed snails/5 weeks value (tcp) as an index the hybrid miracidial infectivity to bulinus forskalii (kinshasa, zaire), the host snail for s. intercalatum, remained compar ... | 1985 | 2868634 |
| [chaetotaxy of gastrodiscus aegyptiacus cercaria (trematoda, paramphistomoidea) a horse parasite]. | cercarial chaetotaxy of gastrodiscus aegyptiacus (paramphistomoidea), parasite of the horse, is described. cercariae were shed by experimentally infected bulinus forskalii. this description is the first one of a gastrodiscidae. the cercarial chaetotaxy of the gastrodiscidae is quite different from those of paramphistomoidea and diplodiscidae. | 1986 | 3813414 |
| [ecological and epidemiological behavior of bulinus forskalii, vector of schistosoma intercalatum bilharziasis]. | | 1972 | 4625637 |
| [ecologic and biologic observations of bulinus forskalii, vector of schistosoma intercalatum schistosomiasis]. | | 1972 | 4677865 |
| studies on the relationship between schistosoma and their intermediate hosts. v. the genus bulinus and schistosoma bovis from iringa, tanzania. | the relationship between an isolate of schistosoma bovis from iringa, tanzania, and various species of the host snail genus bulinus from east africa was studied using the total cercarial production per 100 exposed snails over a period of 4 weeks following patency as an index of the compatibility. all populations of bulinus forskalii and b. africanus tested exhibited a high level of susceptibility while the populations of b. truncatus and b. globosus tested were either refractory or of low to mod ... | 1983 | 6624195 |
| notes on the development of metacercaria and adult of echinostoma porteri fashuyi (echinostomatidae). | the metacercaria of e. porteri was found to retain its viability for a longer time in bulinus (physopsis) globosus (morelet) than in bulinus (bulinus) forskalii (ehrenberg) and lymnaea natalensis (krauss) which is the natural host for other larval stages. it becomes infective to definitive hosts about 6 h after commencement of encystment and loses its viability after 14 days in the snail host. development of adult takes place experimentally in chicks, pigeons and rats, but hosts show age resista ... | 1984 | 6745796 |
| [epidemiologic study of s. haematobium bilharziasis in the rice fields of yagoua (north cameroon) ii. distribution and ecology of intermediate hosts]. | while inventoring the local malacological fauna and evaluating the density of species acting as intermediate hosts of human schistosomes it has been shown that bulinus truncatus is predominant in the study area. bulinus globosus is scarcely encountered. biomphalaria pfeifferi is only found in the mayo guerleo, in irrigation canals and draining ditches. but b. globosus and b. pfeifferi have not yet invaded the recent aquatic network and are not found in the lake nor in the newly created irrigatio ... | 1982 | 7201892 |
| vesical schistosomiasis at odau village in ahoada local government area, rivers state, nigeria. | studies on urinary schistosomiasis and its snail vector was undertaken between october 1991 and september 1992 in odau. of the 890 urine specimens examined 514 (57.8%) were infected. 235 (45.7%) were excreting under 100 eggs per 10ml urine, 167 (32.5%) were excreting between 100-500 eggs per 10ml urine while 112 (21.7%) were excreting more than 500 eggs in 10ml of urine. of the 514 infected persons 336 (60.5%) were males and 178 (53.1%) were females. overall peak infection (78.7%) occurred in 10 ... | 1995 | 7626537 |
| schistosomiasis in dogon country, mali: identification and prevalence of the species responsible for infection in the local community. | the prevalence of schistosomiasis amongst the dogon people in 4 villages and one school of the bankass district of mali was determined during 2 surveys in 1992; 1398 urine and 1199 stool samples were examined. the most common schistosome was schistosoma haematobium, with an overall prevalence of 51.3%; s. mansoni had a prevalence of 12%. no s. intercalatum egg was seen in the stools. biomphalaria pfeifferi and bulinus truncatus were found in pools at the base of the dogon cliffs; bulinus forskal ... | 1994 | 7886759 |
| interspecific stimulation of parthenogenesis in schistosoma intercalatum and s. mansoni. | experimental studies of mating behaviour of schistosoma intercalatum and schistosoma mansoni in mixed infections in mice showed that in simultaneous infections, without the possibility of choice of mate, heterologous pairing occurs readily. the paired females reach sexual maturity, are inseminated and lay parthenogenetic eggs. miracidia originating from the s. mansoni male x s. intercalatum female are non infective to either biomphalaria glabrata or bulinus forskalii, whereas those from the reve ... | 1994 | 7930460 |
| further data on the compatibility between schistosoma intercalatum (lower guinea strain) and bulinus forskalii: epidemiological consequences. | a study of the compatibility between schistosoma intercalatum from cameroon and its potential vectors bulinus forskalii from cameroon, equatorial guinea, ivory coast and niger has been carried out. as compatibility test, the snail infection test, completed by an histological study, was used. snail infection experiments showed that all the populations of b. forskalii we tested are very good potential vectors, with infection rates ranging between 76.5 and 93%. the histological study revealed no de ... | 1993 | 8256102 |
| schistosoma haematobium infection in abeokuta. | ten years after the initial report of the outbreak of schistosomiasis in the vicinity of sokori stream (a tributary of ogun river) in abeokuta, nigeria, investigation was carried out to determine the present status of the disease, given the increased socioeconomic activities in the city. a total of 1670 school pupils in three schools within one kilometer radius of the stream, and 234 adults found using the stream for some water related activities were examined for eggs in their urine. one hundre ... | 1998 | 10456120 |
| [malacologic-schistosomal study of the refugee camps on the plain of ruzizi in the democratic republic of the congo]. | bilharziasis due to schistosoma mansoni is widespread in the eastern part of the people's republic of the congo, particularly in the ruzizi plain area. the intermediate host is the fresh-water snail biomphalaria pfeifferi whose ecology is now well documented. bilharziasis due to schistosoma haematobium and schistosoma intercalatum have not yet been observed but the potential for this development is high given the presence of the intermediate hosts, i.e. bulinus truncatus, bulinus globosus, and b ... | 1999 | 10472580 |
| the influence of self-fertilization and pairing on life-history traits in the freshwater snail bulinus forskalii (gastropoda, planorbidae). | this study analyses the basic reproductive biology of the schistosonie-vector snail bulinus forskalli. this hermaphroditic species can self-fertilize. variation of the mating system was analysed in two populations from cameroon in a three-step experiment. (i) the fecundity (number of eggs and of egg capsules) of isolated virgin individuals from both populations was followed over a month, as well as the survival of offspring from these individuals. estimates of these parameters were intermediate. ... | 2000 | 10936575 |
| experimental evidence of hybrid breakdown between the two geographical strains of schistosoma intercalatum. | reciprocal crosses (schistosoma intercalatum male zaire x s. intercalatum female cameroon: s. intercalatum female zaire x s. intercalatum male cameroon) were produced in 10 mice by exposing each mouse to 60 male cercariae of one isolate and 60 female cercariae of the other isolate, and vice versa. hybrid generations originating from the two crosses were established. the infectivity of the f1, f2, f3 and f4 hybrid generations were evaluated after exposing snails individually to 5 miracidia. a com ... | 2002 | 11862993 |
| a new focus of schistosoma mansoni in yoro village, mbam and inoubou division, cameroon. | investigations on intestinal schistosomiasis were carried out in yoro, a small village located in the transitional zone between forest and savannah, in the mbam and inoubou division of cameroon. four human-water contact points were identified in the village and sampled for snails, and the inhabitants underwent parasitologic and clinical surveys to search for signs and symptoms of intestinal schistosomiasis. the results indicated the presence of two freshwater snails, both potential intermediate ... | 2003 | 12932101 |
| paramphistomum phillerouxi sp. nov. paramphistomatidae) and its development in bulinus forskalii. | | 1961 | 13723003 |
| [schistosomiasis due to schistosoma intercalatum and urbanization in central africa]. | the species name of schistosoma intercalatum, fischer 1934 is linked to the shape and the size of his eggs, which are intermediate between those of s. haematobium and s. bovis. s. intercalatum is the instrument of an intestinal form of schistosomiasis looking like the form induced by s. mansoni but characterized by a low location of the lesions, mainly situated at the rectum and sigmoid level. the spreading area of s. intercalatum is bound to central africa. the foci are often urban and of a siz ... | 2003 | 14582292 |
| distribution patterns and cercarial shedding of bulinus nasutus and other snails in the msambweni area, coast province, kenya. | in the msambweni area of the kwale district in kenya, an area endemic for schistosoma haematobium, potential intermediate-host snails were systematically surveyed in water bodies associated with human contact that were previously surveyed in the 1980s. bulinus (africanus) nasutus, which accounted for 67% of the snails collected, was the only snail shedding s. haematobium cercariae. lanistes purpureus was the second most common snail (25%); lower numbers of bulinus forskalii and melanoides tuberc ... | 2004 | 15100463 |
| [schistosomiasis endemic in burkina faso]. | burkina faso, through the works of many teams of the occge based in bobo-dioulasso, has signi-ficant data on several tropical endemics of which schistosomiasis. with the complementary works, it appears to be possible to establish a distribution of the schistosomiasis which reveals its importance. it will be the first stage of the planned national control program. the parasitologic data-gathering which covers the period of 1951 to 2000, used all the standard techniques. it is about kato-kartz and ... | 2004 | 15104159 |
| breeding system and demography shape population genetic structure across ecological and climatic zones in the african freshwater snail, bulinus forskalii (gastropoda, pulmonata), intermediate host for schistosomes. | the role of breeding system and population bottlenecks in shaping the distribution of neutral genetic variation among populations inhabiting patchily distributed, ephemeral water bodies was examined for the hermaphroditic freshwater snail bulinus forskalii, intermediate host for the medically important trematode schistosoma guineensis. levels of genetic variation at 11 microsatellite loci were assessed for 600 individuals sampled from 19 populations that span three ecological and climatic zones ... | 2004 | 15488012 |
| [dynamics of intestinal schistosomiasis in cameroon: evolution of transmission in the mixed zone of nkolmébanga, lékié]. | this study was undertaken to evaluate the current status of shistosomiasis in the nkolmébanga region (lékié) of cameroon, previously determined to be a mixed zone harboring both schistosoma mansoni and s. intercalatum. study involved both malacology with collection and identification of freshwater snails in four waterpools and parasitology with collection and analysis of stools from schoolchildren. five species of freshwater snails were identified including two that were intermediate host of sch ... | 2004 | 15615385 |
| susceptibility of 7 freshwater gastropod species in zimbabwe to infection with gastrodiscus aegyptiacus (cobbold, 1876) looss, 1896. | gastrodiscosis outbreaks due to gastrodiscus aegyptiacus were recorded in horses in the vicinity of harare, zimbabwe, in the absence of bulinus forskalii, b. senegalensis and cleopatra sp. which are considered to be the only intermediate host snails. this suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. a study was carried out to determine the susceptibility of 7 freshwater snail species to infection with g. aegyptiacus. first gene ... | 2004 | 15830604 |
| epidemiological studies of amphistome infections in cattle in the highveld and lowveld communal grazing areas of zimbabwe. | during the period between january 1999 and december 2000, the distribution and seasonal patterns of amphistome infections in cattle in the highveld and lowveld communal grazing areas of zimbabwe were determined through monthly coprological examination. cattle faecal samples were collected from 12 and nine dipping sites in the highveld and lowveld communal grazing areas, respectively. patterns of distribution and seasonal fluctuations of intermediate host-snail populations and the climatic factor ... | 2005 | 15991706 |
| distribution, habitats and role as intermediate host of the freshwater snail, bulinus forskalii, in south africa. | this paper focuses on the geographical distribution and habitats of bulinus forskalii, the snail intermediate host of the conical fluke of equids, gastrodiscus aegyptiacus as reflected by the 1209 samples in the database of the national freshwater snail collection of south africa. the 362 different loci on record represent an extensive distribution in kwazulu-natal province, the limpopo province, the coastal areas of the eastern cape province and the south-eastern part of the north west province ... | 2005 | 16137134 |
| bulinus forskalii: a new potential intermediate host for schistosoma haematobium in niger. | malacological monitoring of two irrigated areas in niger highlighted the natural susceptibility of bulinus forskalii to infection with schistosoma haematobium when the parasitic load is high. this first report of s. haematobium infection in b. forskalii, which is an abundant snail in irrigated areas, has been confirmed experimentally. | 2007 | 17568645 |
| freshwater snail diversity in benin (west africa) with a focus on human schistosomiasis. | the aim of this study was to conduct a large-scale freshwater snail survey in benin to assess the malacological diversity and the larval trematode infections with a focus on schistosoma genus. we conducted 82 freshwater snail surveys in 35 sites ranked in 4 types and belonging to 9 out of 12 departments. among 19,200 collected snails, 11 species of freshwater snails were identified. four species of human schistosome transmitting snails, bulinus forskalii, b. globosus, b. truncatus and biomphalar ... | 2009 | 19426659 |
| a molecular approach for identification of paramphistomes from africa and asia. | paramphistomiasis is a disease of domestic and wild ruminants caused by some digenetic trematodes of the superfamily paramphistomoidea. human infections with certain species of paramphistomes have been reported. given their ubiquity and their abundance within hosts, it seems likely that the importance of these worms is underestimated globally. based on the reported difficulties of morphological identification of paramphistomes, the development of alternative approaches to better delineate specie ... | 2010 | 20880634 |
| [schistosomiasis and soil-transmitted helminthiasis among schoolchildren of nikki and pèrèrè, two northeastern towns of benin]. | infection with schistosomiasis and soil-transmitted helminthiasis are widespread in sub-saharan africa and the burden of disease associated with parasites is enormous. a study was performed to determine the transmission and prevalence of human schistosomiasis and soil-transmitted helminthiasis among school children of nikki and perere, two north eastern towns of benin, bordering republic of nigeria. parasitological investigations by urine filtration and kato-katz conducted on 1,344 school childr ... | 2014 | 24595888 |
| the spatial and seasonal distribution of bulinus truncatus, bulinus forskalii and biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, in n'djamena, chad. | there is a paucity of epidemiological and malacological data pertaining to schistosomiasis in chad. in view of a recently articulated elimination agenda, a deeper understanding of the spatio-temporal distribution of schistosomiasis intermediate host snails is pivotal. we conducted cross-sectional malacological surveys during the dry season (april/may 2013) and after the short rainy season (october 2013) in n'djamena, the capital of chad. snails were identified at the genus and species level usin ... | 2014 | 25545929 |
| [epidemiology of urinary schistosomiasis among school children in péhunco area, northern benin. malacological survey]. | schistosomiasis is a public health problem in benin but prevalence estimates vary widely. parasitological (from may to september 2010) and malacological surveys (from september 2010 to june 2012) were conducted to determine the current status of urinary schistosomiasis among 1 585 schoolchildren from 18 primary schools of péhunco area, north-west benin, using two parasitological tests. pupils were enrolled with a mean age of 11 years (from 7 to 16 years-old age) and 51.48% of them were girls. ur ... | 2014 | 24615433 |
| a high incidence of clustered microsatellite mutations revealed by parent-offspring analysis in the african freshwater snail, bulinus forskalii (gastropoda, pulmonata). | genotyping of 11 microsatellites in 432 offspring from 28 families of the hermaphroditic, freshwater snail bulinusforskalii detected 10 de novo mutant alleles. this gave an estimated mutation rate of 1.1 x 10(-3) per locus per gamete per generation. there was a trend towards repeat length expansion and, unlike most studies, multi-step mutations predominated, suggesting that the microsatellite mutation process does not conform to a strict stepwise mutation model. interestingly, the ten mutant all ... | 2005 | 16011005 |
| molecular evolution of freshwater snail intermediate hosts within the bulinus forskalii group. | freshwater snails of the bulinus forskalii group are one of four bulinus species complexes responsible for the transmission of schistosomes in africa and adjacent regions. the species status of these conchologically variable and widely distributed planorbids remains unclear, and parasite compatibility varies considerably amongst the eleven taxa defined, making unambiguous identification and differentiation important prerequisites for determining their distributions and evolutionary relationships ... | 2001 | 11769290 |
| [epidemiology of certain endemic parasitic diseases in the town of guadalupe (republic of sao tome and principe) i. schistosomiasis intercalatum and intestinal worms]. | schistosomiasis intercalatum in known to exist in saõ tomé since 1988, (corachan et al.). it is transmitted by bulinus forskalii, (brown et al., 1989). stool, blood and urine specimens have been collected from 380 inhabitants of all age groups living in the small town of guadalupe close to the agua traź river and agua polino. the prevalence of schistosomiasis by detection of s. intercalatum eggs in a 10 mg stool thick smear (kato technique) is 25.5%. an excreted schistosoma polysaccharide antige ... | 1996 | 9053044 |
| [experimental taxonomy of bulinus (gastropoda:planorbidae). vi. the possibility of using enzyme characteristics for the distinction between the species bulinus liratus and bulinus obtusispira in madagascar]. | based on a study of one laboratory culture of each of the three species bulinus forskalii, b. obtusispira and b. liratus it is shown that the two last mentioned species differ in enzyme mobility in seven out of eight enzymes investigated. it is pointed out, that, prior to using enzyme characters for identification purposes, a study of the intra- and interpopulation variation should be carried out. it is mentioned, that the difference in absolute mobility, the quality of the bands and the price f ... | 1984 | 6534293 |
| [research on the life-cycle of metahaematoloechus exoterorchis (rees, 1964) (digenea) parasite of lungs of the frog dicroglossus occipitalis (gunther, 1858) in togoland (author's transl)]. | the sporocysts and xiphidiocercariae of metahaematoloechus exoterorchis evolve in the planorbid segmentorbis kanisaensis (preston); experiment shows that gyraulus chudeaui (germain) and bulinus forskalii (erhenberg) are possible vectors. cercariae encyst in larvae of several dragonflies. m. exoterorchis adult, is usually harboured by dicroglossus occipitalis, but experimentally develops in the frog contraua derooi hulselmans, 1971. | 2006 | 677720 |
| studies in schistosomiasis in sierra leone. ii. seasonal fluctuation in the population density of bulinus (physopsis) globosus and bulinus forskalii in a schistosomiasis endemic town in sierra leone. | | 1972 | 4634779 |