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 1,495 records · Page 83Linked to original sources
PubMed1979

The specific methods of control and eradication of schistosomiasis in Israel.

A review of the epidemiological status of urinary schistosomiasis and intestinal schistosomiasis in Israel is made. The ecology, bionomy and geographical distribution of the snail vectors were studied and research on their vectorial capacity to the imported Schistosoma strains was undertaken. Biomphalaria alexandrina, the snail vector of S. mansomi, was eradicated through ecological factors (salinity and pollution by sewage) and human activities. The elimination of snail vectors by applications of chemicals succeeded when the entire infested foci were isolated. The factors responsible for the reappearance of snail vectors after those chemical applications are described. Examples are given of successfully combined measures used for the control of snail vectors; increase of water currents to over 20 cm/sec, rapid emptying and drying up of water reservoirs, weekly deflection of infested water courses in different directions, etc. In 1951, 19 schoolchildren became infected with S. mansoni and in 1955, 97 schoolchildren became infected with S. haematobium. Since 1955 no more new infections with Schistosomiasis have been reported in Israel.

Biomphalaria↗
PubMedDate not supplied

Assessment of schistosomiasis in the Dominican Republic.

Active transmission of intestinal schistosomiasis is currently limited to the southeastern part of the Dominican Republic. A population-based stool survey in 1980 detected 4 asymptomatic individuals among 114 selected at random in 2 towns and a rural community in El Seibo Province. The distribution of the transmitting snail, Biomphalaria glabrata, considerably exceeds that of Schistosoma mansoni, extending to the National District and capital city of Santo Domingo and well into certain central valley provinces. There is evidence that transmission sites have shifted during the past three decades because of urban development, molluscicidal activities and, perhaps, introduction of competing mollusks. In spite of intermittent control activities, the combination of domestic and recreational use of streams with consequent fecal contamination, and the extended distribution of B. glabrata indicates that the potential for new transmission foci is as great today as it was 10 years ago. This potential transmission of S. mansoni is a continuing threat to public health in the Dominican Republic.

Adolescent↗
PubMed1986

Lectin-dependent cell-mediated cytotoxicity in an invertebrate model: Con A does not act as a bridge.

The plant lectin concanavalin A (Con A) has been used in an invertebrate model of lectin-dependent cell-mediated cytotoxicity (LDCC). Macrophage-like cells from the susceptible host snail Biomphalaria glabrata become cytotoxic effectors when they encounter sporocysts of the parasitic trematode Schistosoma mansoni that have been treated with Con A. The sugar alpha-methyl mannoside and rabbit anti-Con A antibodies fail to block this LDCC. Con A is effective only when the target, not the effector cell, has been exposed to it. These results constitute evidence against the molecular bridging hypothesis and support the notion that surface modulation of the target may be the stimulus that provokes cytotoxicity. Results from this invertebrate model are discussed in the context of murine T lymphocyte LDCC.

Animals↗
PubMedDate not supplied

[Epidemiologic study of intestinal and urinary bilharziasis in the Tala Mokolo region (Mandara Mountains, North Cameroon)].

In the Mandara Mountains, where small dams have been erected, people living in the Tala Mokolo district eliminate some S. haematobium eggs in 31,4% of urines samples, and some S. mansoni eggs in 38,1% of stools samples. Evaluated from hemagglutination test, bilharziosis prevalence reaches 55,7%. Male subjects are more frequently affected than female subjects, particularly as for as intestinal bilharziosis is concerned. Urinary bilharziosis prevalence or intestinal bilharziosis prevalence are subject to proximity of small water reservoirs mostly infested either by Bulinus globosus or Biomphalaria pfeifferi. These small water reservoirs are mainly "mayo" head-bays.

Adolescent↗
PubMed1985

Focality and seasonality of Schistosoma mansoni transmission in the Gezira Irrigated Area, Sudan.

In the Gezira Irrigated Area of Central Sudan, transmission of Schistosoma mansoni was shown to be geographically focal, being concentrated near villages and small settlements. In a study during 1981 and 1982 of the entire area around a typical Gezira village almost 90% of the Biomphalaria pfeifferi snails carrying schistosome infections were found in one minor canal near the village. Sites near smaller settlements some distance from the minor canals yielded few infected snails. The factors which influenced the prevalence of infection in the snails were temperature, turbidity and human contact with the snail habitat. A strategy was proposed for control of Schistosoma transmission through focal and seasonal mollusciciding, health education, chemotherapy, improved water supply and latrine distribution.

Agriculture↗
PubMed1985

Snails and aquatic vegetation in Gezira irrigation canals.

All 38 minor canals in a limited area of the Gezira Irrigated Area were surveyed four times over a 2-year period to determine the aquatic and semi-aquatic vegetation types found and their distribution. A more detailed 2-year study of the correlation between snail density and aquatic vegetation was carried out in 18 of these canals. A total of 22 different species of weed were recorded, with floating and submerged weeds being more widespread and dense in the clear, slow-moving water at the end of the irrigation season in March/April, than in the turbid flood waters in October. The schistosome vector snails Biomphalaria pfeifferi and Bulinus truncatus were found in conjunction with aquatic weeds and B. pfeifferi in particular increased in numbers as weed growth continued. In the second season of the study when mechanical weed clearing and regular focal mollusciciding was being carried out there was a noticeable reduction in weed density but repopulation was rapid. Snail numbers were reduced by mollusciciding and/or weed clearance in four canals, but outside the focal target canal stretches the weed clearance alone did not substantially reduce the snail populations.

Agriculture↗
PubMed1985

Molluscicidal properties of Acacia nilotica subspecies tomentosa and astringens I.

The acetone, alcohol and aqueous extracts of the fruits and stem bark of Acacia nilotica subspp. tomentosa, astringens and nilotica showed molluscicidal activity against the two snail species which transmit schistosomiasis in the Sudan. Being effective against Bulinus truncatus and Biomphalaria pfeifferi, extracts of the Acacia nilotica subspecies may be promising vegetable molluscicides.

Acacia↗
PubMed1985

Molluscicidal properties of Acacia nilotica subspecies tomentosa and astringens II.

A screening programme of plants rich in plant phenolic tannins for molluscicidal activity against the snail species Bulinus truncatus and Biomphalaria pfeifferi is now under way. The spray-dried powders of the pods and stem bark of Acacia nilotica subspp. nilotica, tomentosa and astringens prove to be promising vegetable molluscicides.

Acacia↗
PubMed1972

Effect of a control programme on transmission of Schistosoma mansoni on an irrigated estate in Tanzania.

Three methods were used to measure the level of transmission of infections of Schistosoma mansoni on an irrigated sugar estate in northern Tanzania. The studies were carried out over a period of 3 years, during a programme for the control of the host snail Biomphalaria pfeifferi. During the second and third years a mass diagnosis and treatment campaign against the infection was also carried out. Examinations for infection were made in newly employed subjects on arrival and after 6 and 12 months. Two studies were made in young children at an interval of 18 months, to determine age prevalence curves. In the third method, subjects were examined for infection 18 months after being found free from infection in a previous survey. Results are compared with data recorded in a previous study, made before snail control was commenced. The results suggest that the control programme has led to a great reduction in the incidence of S. mansoni on the estate.

Agricultural Workers' Diseases↗
PubMed1972

The effect of a control programme against Schistosoma mansoni on the prevalence and intensity of infection on an irrigated sugar estate in northern Tanzania.

On an irrigated sugar estate in northern Tanzania a control programme against Schistosoma mansoni was carried out during 1968-70. Through the routine use of molluscicides, the population of Biomphalaria pfeifferi snails was kept at a greatly reduced level. Concurrently a mass campaign was carried out to detect residents who were infected with S. mansoni so that they might be treated. The effect of these measures on the overall prevalence of the disease was measured by random studies before and after the mass diagnosis and treatment. The techniques used for mass diagnosis, for treatment, and for the prevalence studies are described, and the results of the control programme are presented and discussed. In the mass diagnosis campaign over 90% of the population were examined and 2 286 courses of treatment were administered to 1 922 persons. The combination of chemotherapy and snail control led to a significant reduction in the number of S. mansoni. infections. In field workers the prevalence was reduced from 59% in early 1969 to 31% in late 1970. In nonfield workers the reduction was from 36% to 15% and in the wives of employees from 28% to 14%. The main reasons why the prevalence was not reduced further were considered to be the failure of the drugs used to effect a complete parasitological cure and the inability of the mass diagnosis campaign to detect light infections. It was estimated that the overall reduction in the number of eggs released into the community as a result of the control programme was about 85%.

Adult↗
PubMed1973

Molluscicidal activity of trifenmorph in field trials.

Trifenmorph granules provided 100% control of Biomphalaria glabrata and B. tenagophila when applied at 2 kg of active ingredient per hectare, except at one site with a pH of 5.6 where the snail population was reduced by only 50%. Granulation was found to facilitate application by either hand or mistblower, and reduces the risk of infection to the spray team. Applied to canal margins the granules had a residual toxic effect.

Animals↗
PubMed1979

Biological control of schistosome transmission in flowing water habitats.

Marisa cornuarietis was evaluated in Puerto Rico for control of schistosome transmission in flowing water. A population of Biomphalaria glabrata and their schistosome infections disappeared after introduction of 20,000 M. cornuarietis to an endemic stream, while in nearby untreated streams the B. glabrata population remained stable and the schistosome prevalence increased. This method cost U.S. $0.10 per capita for over a year of protection, 5%-10% of the cost of chemical control.

Animals↗
PubMed1971

Electrophoretic studies on the digestive gland esterases of some biomphalarid and lymnaeid snails.

Because of the problems encountered in the classification of snails of medical importance, biochemical methods have been sought to help clarify the situation. Of these, the separation of the enzymes of adult snails by electrophoresis seems the most promising but very few attempts have been made so far to use the results for taxonomic studies. The purpose of the present study was to evaluate the use of the enzyme systems of neotropical planorbid and of lymnaeid snails to elucidate their taxonomy and also snail-schistosome relationships at the species and population levels.The findings show the characteristic electrophoretic patterns of digestive gland esterases of the planorbid and lymnaeid snails used, as well as their variation and the level of such variation among certain populations and the consistency of the patterns among others. The results also show that, in general, the extent of variation between some populations of the same species is greater than the differences between species of the same group. However, at the specific level, there are similarities suggesting close relationships between some populations of Biomphalaria glabrata and B. tenagophila on the one hand, and of certain populations of B. peregrina and of B. obstructa on the other hand.The present study has thrown some light on the question of electrophoretic variation in enzymes, and the ways in which this can be applied to studies of the genetics of snails. A correlation is suggested between certain patterns that indicate biochemical similarities or differences among the planorbid snail populations and the susceptibility of the species or the population to infection with the schistosomes.

Animals↗
PubMed1978

Prevalence of schistosomiasis among fishermen of Lake Maryut.

A survey was carried out to investigate the presence of Bilharziasis among the fishermen of the lake Maryut. Schistosoma mansoni is more prevalent, than S. haematobium among fishermen of lake Maryut. Biomphalaria alexandrina, snails were prevalent around the lake specially in places of low salinity, where fresh water discharges exist. Bulinus truncatus snails were not found during the time of the present survey and more frequent surveys are needed. There is an inverse relation between the number of snails and the salinity of the water. Since the salinity of the water is decreasing by time as a result of the increased discharge of agricultural and domestic waste into the lake, Bilharziasis infection may increase among the fishermen. This situation needs more attention from public health authorities in the area.

Adolescent↗