Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Biomphalaria”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,441 records · Page 80Linked to original sources
PubMedDate not supplied

[Cell culture of snails. Their use in the study of immunologic host-parasite relationships in schistosomiasis].

The host-parasite relationship between Schistosoma mansoni and the snail Biomphalaria glabrata is so complex that its experimental study needs some particularly working methods: for instance molluscan organs and tissue's cultures. In the experiment described we report that digestive gland's cells cultures were grown on synthetic cultural medium. This one contained a physiological salt solution and a basal nutrient medium consisting of foetal calf serum, chicken embryo extract and amino-acids. In this case we observed good growth and multiplication of the digestive gland cells. This preliminary experiment has to be used in immunological studies regarding the origin and the mode of acquisition of the snail antigen by the cercariae membrane.

Animals↗
PubMed2002

Biological studies on the snail intermediate hosts of schistosomiasis with a special emphasis on using larval echinostomes as biocontrol agent against larval schistosomes and snails.

The present investigation deals with the infectivity of the two snail intermediate hosts of schistosomiasis, Biomphalaria alexandrina and Bulinus truncatus collected from nine drains in Sharkia Governorate, Egypt. The rate of infection among the snails was general low being 0% in many drains. Regarding B. alexandrina, the rate of infection ranged from 4-16%, and in B. truncatus ranged from 4-8%. Infection with larval echinostomes was dominant over larval schistosomes in the two snail vectors. The distribution of larval schistosomes was restricted to the hepatopancreas of the two snail vectors, while larval echinostomes were distributed in head, foot, kidney, haemocoelic cavity, hepatopancreas...etc. The predation of larval schistosomes by larval echinostomes and the severe histopathological effects induced by larval ecbinostomes strongly enhances using them as biocontrol agent. The physico-chemical parameters and pollution condition in the drains seem to have no effect on the process of snails infectivity. It is concluded that larval echinostomes can resist the polluting conditions in the drain. The two snail vectors exhibit very minimal or rare host response against larval echinostomes. Probably, the toxicants and pollutants in the drain may act as stressor that makes the snails much more susceptible to infection by larval trematodes.

Animals↗
PubMed1976

Studies on resistance in snails. 6. Escape of Echinostoma lindoense sporocysts from encapsulation in the snail heart and subsequent loss of the host's ability to resist infection by the same parasite.

Formation of amebocyte aggregates in the ventricular cavity of Biomphalaria glabrata, induced by developing sporocysts of Echinostoma lindoense, does not always result in destruction of the parasites, as the sporocysts occasionally escape encapsulation in the heart. When this occurs, a remarkable loss of protective capacity follows and the host snails become highly susceptible to reinfection with the same species--even more so than in control susceptible snails exposed for the first time. Although the amebocyte-producing organ is considerably enlarged after a first infection and shows numerous mitoses, the amebocytes produced by snails harboring an "escaped" infection in the heart appear unable to attack the parasites of the first or of the second exposure. Instead, the amebocytes produced accumulate in the loose connective tissues between the liver lobuli, where early developmental stages of the parasites do not occur. These amebocytes apparently have lost their ability to recognize the parasites as foreign.

Animals↗
PubMedDate not supplied

[The use of the shell of the cashew nut, Anacardium occidentale, as an alternative molluscacide].

Bioassays using hexanolic extracts of cashew nut shells, of Anacardium occidentale, collected in Ceará in 1972 (Sample 1) and 1987 (Sample 2) were undertaken with adult snails and egg masses of Biomphalaria glabrata, B. tenagophila and B. straminea both in the laboratory and in the field. Non extracted shells, 18.5 g, sample 1, were also tested with adult snails and egg masses of the three species. The toxicity of extract was tested with fish (Poecilia reticulata) and tadpoles. The lethal concentration, CL90, of sample 1 was from 2.0 to 2.2 ppm for adult snails of the three species. With sample 2, the CL90 was 2.0, 0.5 and 30.0 ppm for B. glabrata adults, newly hatched snails and egg mass respectively. Non extracted shells caused 40-80% mortality of adult snails, 22-35% mortality of embryos and 40-55% reduction of egg production. The hexanolic extract, sample 2, were innocuous for tadpole and fish at 2 ppm. In the field, in pools of still water treatment with 20 ppm of extract, sample 1, caused a 97.1% mortality of B. straminea and 100% mortality of B. glabrata and B. tenagophila. Using Niclosamide, at 3 ppm, 100% mortality of the three species occurred.

Animals↗
PubMedDate not supplied

[A survey of Planorbidae in the state of São Paulo: the 8th Administrative Region (the greater São Jose do Rio Preto area)].

In order to know the distributional patterns of Basommatophoran snails in the state of São Paulo (Brazil), 85 "counties" in the area of S. José do Rio Preto were worked out during seven months (1982). Snails from 286 breeding places were collected and identified. Biomphalaria straminea, an intermediate host of S. mansoni, was found in four little ponds, in the neighbourhood of Altair and S. José do Rio Preto. It was concluded that schistosomiasis has little chance to spread out in the studied area.

Animals↗
PubMed1958

Distribution of the intermediate hosts of bilharziasis in relation to hydrography; with special reference to the Nile Basin and the Sudan.

The author has made a collection from certain parts of the Sudan of snails of the genera Bulinus and Biomphalaria that are actual or potential vectors of bilharziasis. The snails were identified by anatomical examination and a preliminary interpretation of the findings is given. The results are related to information already available, not only from the Sudan, but also from adjacent areas, especially from the Nile basin in general. The distribution of the snails is shown both in tabular and in map form. With a view to providing a basis for a better understanding of the true relationships among this group of African planorbids, special consideration has been given to the hydrographic and hydrogeological factors which have brought about the present distribution.

Animals↗
PubMed1964

OBSERVATIONS ON BILHARZIASIS AND THE POTENTIAL SNAIL HOSTS IN THE REPUBLIC OF THE CONGO (BRAZZAVILLE).

In 1962, the author conducted a preliminary investigation of bilharziasis in the Republic of the Congo (Brazzaville), at the request of the Government, in order to review existing information and work done on bilharziasis, to assess the prevalence and distribution of the disease, to make observations on the potential snail hosts, and to propose further suitable studies and control measures.Although little time was available for this study, it appears reasonable to conclude that Schistosoma haematobium is confined to a few foci in the west of the country, the main snail host being a new subspecies of Bulinus (B.) truncatus. Intestinal bilharziasis is apparently very rare, but systematic stool surveys have not been done; S. mansoni may be, or become, endemic at Dolisie, where Biomphalaria camerunensis is abundant. The main factors governing the restricted distribution of bilharziasis are discussed.Bilharziasis control appears to merit relatively low priority compared with that due to several other diseases, and the author concludes that bilharziasis is unlikely to become widespread in future years unless there is major environmental change, although the intensity of transmission may increase in some present endemic foci.

Animals↗
PubMed1992

[Complement to the epidemiologic study of the focus of Schistosoma mansoni bilharziasis in Kara (northern Togo)].

The present study on the focus of schistosomiasis mansoni of Kara (Northern Togo) complements a report already published in the Bulletin de la Société de Pathologie Exotique in 1988 (9). The following results were obtained through different experiments carried out with snails collected in Kara. According to the season, 3 to 15% of the Biomphalaria pfeifferi studied, were infected. The maximal release of cercariae was observed between 11 am and 1 pm. The survival of cercariae and their ability to infect mice were not superior to 16 hours. Data obtained with the chaetotaxy of miracidia of the Kara strain were compatible with those obtained with african strains by other authors. Moreover, B. pfeifferi from Kara was more susceptible to the Kara strain of Schistosoma mansoni than B. pfeifferi collected in the south of Togo or than B. glabrata from the new world. On the contrary, B. pfeifferi from Kara was susceptible to a strain of S. mansoni from Brazil and was able to produce infectious cercariae. In addition, the search for an animal reservoir was carried out; 3 of the 112 (2.7%) wild rodents captured around the river Kara, were infected. This relatively low number of infected rodents was compatible with the usual findings in Africa where the animal reservoir is considered from human origin and has no importance in the transmission of S. mansoni as it could have in South America and West Indies.

Animals↗
PubMed1965

PRELIMINARY FIELD TRIALS OF ACROLEIN IN THE SUDAN.

Field trials of acrolein for the simultaneous control of aquatic weeds and snails were conducted in the Sudan.Phytotoxicity studies at 25 and 50 ppm showed minor or no damage to furrow-irrigated crops, but flood irrigation of vegetable seedlings at 15 ppm was toxic.Effective downstream carriage of acrolein was demonstrated for a distance of 1.6 km at a concentration of 25 ppm. Planorbid snails (Bulinus and Biomphalaria) were almost completely eliminated (98-99% kills). All submersed aquatic weeds were destroyed.

Acrolein↗
PubMed1960

Intermediate hosts of Schistosoma in Africa. Some recent information.

Dr Mandahl-Barth's monograph on the intermediate hosts of Schistosoma in Africa, published by the World Health Organization in 1958, attempted to clarify the complicated subject of the taxonomy of Biomphalaria and Bulinus-the snail vectors of bilharziasis in Africa. The classification of these vectors, however, is still far from being cut-and-dried, and each fresh fact unearthed must be regarded as a potential challenge to its validity. Since the publication of the monograph a great deal of further material has been submitted to the WHO Snail Identification Centre at Charlottenlund, Denmark. The additional information collected, together with some amendments to the earlier data, is presented in this supplementary contribution to the monograph.

Africa↗
PubMed1962

Key to the identification of east and central African freshwater snails of medical and veterinary importance.

This identification key has been prepared to enable field workers in eastern and centra Africa to identify the species and subspecies of snails acting as intermediate hosts of various flukes causing bilharziasis and related diseases in man and his domestic stock.The area covered by the key is eastern Africa from the Sudan and Somalia in the north to Southern Rhodesia in the south. The key includes all species and subspecies of the three medically and veterinarily important genera, Lymnaea, Bulinus and Biomphalaria. All other freshwater pulmonates of the area can be identified as to genus only.Those features of the shells and soft parts of snails which are used in identification are discussed in some detail, and indications are given as to methods of collection, preservation and dissection of snails.

Africa↗
PubMed1992

Schistosoma mansoni in Pachwach, Nebbi District, Uganda, 40 years after Nelson.

Human- and snail-related aspects of the transmission of schistosomiasis mansoni was studied in the Amor Parish community located at the western bank of the River Nile in the Nebbi District, north-western Uganda. A cross sectional survey involving 642 people revealed an overall prevalence of infection among males and females of 81.6% and 81.3%, respectively. The prevalence of infection peaked in the 10-14 years age group, being 93.2% and 93.6% in males and females, respectively, but the prevalence remained high also in older age groups. Intensity of infection peaked in the 10-14 years age group in males and in the 15-19 years age group in females, reaching 768 and 482 eggs/g faeces, respectively. Intensity of infection diminished only to a moderate extent with increasing age with the infection intensity in the 40+ years age group being 270 and 241 eggs/g faeces in males and females, respectively. Observations on the human water contact pattern revealed a community having a very intensive water contact persisting into old age. Interviews revealed a high level of awareness of the disease schistosomiasis, and 87.2% had a history of passing blood in stool. The total set of observations point to intestinal schistosomiasis being of public health importance in Amor Parish. Studies on snail-related aspects of transmission revealed that Biomphalaria stanleyi was by far the most important snail host in the area. A tendency was seen for B. stanleyi snail numbers to be reduced during the rainy season.

Adolescent↗
PubMed2003

Molluscicidal and in-vitro schistosomicidal activities of the latex and some extracts of some plants belonging to Euphorbiacea.

Plant molluscicicdes proved to be good means for controlling fresh water snails of schistosomiasis. The molluscicidal activities of the natural and lyophilized latex extracts of Euphorbia royleana and E. mouritanica and acetonitril and chloroform extracts of Jatropha carcus were investigated against Biomphalaria alexandrina the intermediate hosts for S. mansoni. The lyophilized latex extract of E. royleana showed the highest toxicity against snails with LC90 value of 11 ppm. While the natural latex extract of E. mouritanica showed the lowest toxicity against snails with LC90 value of 60 ppm. While, the acetonitril extract of Jatropha carcus gave high toxicity against snails with LC90 value of 6 ppm and the chloroform extract gave low toxicity against snails with LC90 value of 55 ppm. The in-vitro schistosomicidal activities of the lyophilized latex extract of E. royleana and the acetonitril extract of J. carcus were studied against S. mansoni adults showed that the lyophilized latex extract of E. royleana gave 100% mortality after exposure to 30 ppm for 4 consecutive days and 66.7% mortality after exposure to 10 ppm for 5 consecutive days. The acetonitril extract of J. carcus gave 91.7% mortality after exposure to 100 ppm for 4 consecutive days and 58.3% mortality after exposure to 50 ppm for 5 consecutive days.

Animals↗
PubMed2003

The effects of myrrh (Commiphora molmol) on the infected snails of Schistosoma sp. and their egg masses: effect on shedding of cercariae and on snail fecundity.

Myrrh has molluscicidal effect on infected Bulinus truncatus and Biomphalaria alexandrina snails at low concentrations (10 & 20 ppm respectively) after 24 hours exposure. The number of dead-snails increased with prolongation of exposure time. All Schistosoma free cercariae were killed by 2.5 ppm within 15 minutes. One day-old egg masses were more susceptible to the ovicidal effect of Myrrh than the five-day old ones. Both types of eggs were more resistant to the effect of Myrrh than the adult snails, embryogenesis began to stop at 20 ppm and eggs were all killed at 60 & 80 ppm. Shedding of cercariae of Schistosoma mansoni from infected B. alexandrina stopped at 1 ppm and was suppressed at 0.8 ppm. Snail fecundity decreased at 1 ppm.

Animals↗
PubMed1992

Ultrastructural aspects of intramolluscan developing cercariae of Echinostoma liei.

The ultrastructure of the daughter redia of Echinostoma liei inside their host Biomphalaria alexandrina is described. The tegument consists of one layer, bearing numerous microvilli on its outer surface. Besides, the description of the ultrastructure of the developing cercariae within the daughter rediae is also included in the present study. The young cercariae are covered with a thin nucleated primitive temporary epithelium, which is lost when the true tegument is formed beneath it. The mechanism of spine formation was not apparent, but there is some indication that the spines are associated with a thickened part of the basal membrane of the tegument. Section through these cercariae showed that the tissues lying below the tegument are disposed in consecutive layers, suggestively representing developing muscle tissues.

Animals↗
PubMed2004

[Recent evolution of schistosomiasis in the water project of Sourou in Burkina Faso].

In order to help the hydro-agricultural projects in the management of water resources together with a schistosomiasis control programme, it is important to evaluate the extent of the problem. This is the reason why parasitological and clinical surveys were conducted in schools associated with malacological surveys in transmission sites of several water projects including the one from Sourou. The data-collecting for the research on molluscs was carried out in surface water and as for parasitologic investigations on school-aged children, urine filtration and Kato-Katz were used to evaluate the parasitic load. The levels of prevalence were respectively in Guiédougou, Niassan, Di and Toma-île, in 2000, 60.5%, 40%, 48.8% and 51.9% for the urinary schistosomiasis, 5.3%, 0%, 6.9% and 50.6% for the intestinal schistosomiasis and in 2002, 56%, 51.9%, 51.6% and 43.4% for the urinary schistosomiasis, 10.1%, 8.2%, 22.7% and 90.8% for the intestinal schistosomiasis. The molluscs species collected and identified were: Biomphalaria pfeifferi for the intestinal schistosomiasis and Bulinus truncatus rohlfsi and B. senegalensis for the urinary schistosomiasis. B. senegalensis and B. truncatus were found naturally infested by S. haematobium. Water projects constitute amplifying factors of the proliferation of the species and parasitic exchange. All the actors (developers, populations, scientists) are questioning the means at their disposal to reduce the development of schistosomiasis which decrease the expected benefit of hydro-agricultural installations.

Agriculture↗
PubMed2004

[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 MIF for the intestinal schistosomiasis, centrifugation, filtration, serology reagent strips, macroscopy of urines and echography of the urinary system for the urinary schistosomiasis. All the eleven medical areas of the country have many sites submitted to parasitologic investigation. As regard the distribution of the two parasites involved with man (Schistosoma haematobium and S. mansoni), the data of prevalence (1% to 100%) and their distribution confirm their endemicity and the focal transmission. S. mansoni is located in eight medical areas particularly in the South and the West. S. haematobium is present in all the eleven medical areas of the country. In hydraulic planning as Sourou where the prevalences went from 23% to 70% for S. haematobium and from 0% to 69% for S. mansoni between 1987 and 1998. The situation requires a continuous monitoring. The spatial distribution of the six species of intermediate hosts shows that Bulinus truncatus and B. senegalensis Soudano-Sahelian species are present in all the ecological zones. B. globosus and Biomphalaria pfeifferi meet preferentially in the southern half of the country which reinforces the observation according to which the 14th northern parallel is often considered as the limit of septentrional extension of these two species. The other species Bulinus forskalii and B umbilicatus could have preference areas. All the species show a certain affinity with a type of biotope. The rarity and temporary aquatic systems lead to a concentration of the domestic and especially entertaining children activities around these biotopes very often contaminated. The phenomenon is amplified by the increase of contacts man-water, whose frequency and intensity are themselves dependent on activities related to hydro-agricultural planning. The analysis of the data shows, that in terms of colonization of the biotopes by molluscs and the relations between parasites and intermediate and final hosts, hydraulic planning turns out to be an amplifying factor of the species proliferation and parasitic flux host-parasite.

Agriculture↗
PubMed1992

Biological control of the snail intermediate hosts of Schistosoma mansoni in Martinique, French West Indies.

In Martinique water-cress beds constituted the last transmission sites for schistosomiasis. The competitor snail, Melanoides tuberculata, was introduced at the beginning of 1983 to a group of water-cress beds and eliminated the snail hosts, Biomphalaria glabrata and B. straminea, in less than two years. Following this first success, M. tuberculata was introduced to the other groups of beds which were inventoried at the beginning of the eighties. At the present time, B. glabrata and B. straminea have totally disappeared from eight sites and only a few individuals have been recorded from 12 sites. The two remaining water-cress beds have dried up and were abandoned.

Animals↗