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PubMed1998

The molluscicidal activity of Crown of Christ (Euphorbia splendens var. hislopii) latex on snails acting as intermediate hosts of Schistosoma mansoni and Schistosoma haematobium.

The present study describes the action of the latex of Euphorbia splendens var. hislopii (E. milli) on species of the genus Bulinus and on Biomphalaria pfeifferi, intermediate hosts of schistosomiasis in Africa, and the Brazilian snails B. glabrata, B. tenagophila, and B. straminea, intermediate hosts of schistosomiasis in Brazil. The impact of the latex on the egg masses and embryos of B. glabrata was also evaluated. Using the standardized methodology of the World Health Organization for testing plant-derived molluscicides, we obtained a 90% lethal dose (LD90) ranging from 0.13 ppm for B. glabrata subjected to lyophilized latex to 4.0 ppm for B. pfeifferi tested with the natural latex. This material has proved to be one of the most potent and specific plant molluscicides discovered thus far, presenting advantages in terms of application so that it could be used in programs involving community participation in endemic areas in both Brazil and Africa.

Animals↗
PubMed1999

Emergence of Schistosoma mansoni infection in upper Egypt: the Giza governorate.

We found an unexpectedly high prevalence of Schistosoma mansoni in a village in the Upper Egyptian governorate of Giza. Historically, S. mansoni is endemic in the northern Egyptian Nile Delta rather than in the southern Upper Egypt. This observation was made during an evaluation of a rural health care schistosomiasis surveillance program using a cross sectional survey for S. haematobium and S. mansoni in the village of El-Gezira El-Shakra El-Saf district in the Upper Egypt Giza Governorate. A 10% systematic random sample of households of the village was chosen. All persons in the selected houses were invited to submit urine and stool samples. All students from a primary school were also included in the study. Urine was screened by a polycarbonate filtration method and stool was examined using modified Kato-Katz technique. The prevalence of S. mansoni in the population sample and in the school children was 33.7% and 57.7%, respectively, whereas the prevalence of S. haematobium infection in the population sample and the school children was 7.4% and 10.6%, respectively. The prevalence of infection was highest in the younger age groups, and males were infected more than females. Review of Ministry of Health records showed that both species of vector snails, Bulinus truncatus and Biomphalaria alexandrina, were present from 1991 to 1995, and that B. alexandrina was more abundant than B. truncatus in the canals surrounding this village. The unexpected high prevalence of S. mansoni in this village indicates an urgent need to include training programs for S. mansoni surveillance in the primary health care facilities of Giza and to educate villagers to request examinations for S. mansoni as well as for S. haematobium infection.

Adolescent↗
PubMed1976

Influence of diet on breeding and infectivity in mass cultivation of Bulinus truncatus.

Under well defined laboratory conditions as troughs, room temperature, humidity, water, and air supply Bulinus truncatus was bred and kept. In a feeding trial high protein diet consisting of powdered mice pellets, commercial tropical fish food and lettuce was compared to poor protein diet of lettuce alone. Higher yield of clutches, eggs and cercariae were observed in the rich protein diet group, Bulinus and Biomphalaria Snail seem to be influenced by diet in the same way.

Animals↗
PubMedDate not supplied

[Presence of Angiostrongylus cantonensis in the Réunion Island. Isolation of the strain].

The detection of some cases of eosinophilic meningitis suggest that Angiostrongylus cantonensis is present in Reunion Island. Larvae of this nematode have been isolated after dissection of Achatina fulica and have been used to infest laboratory rats. 30 days later, the dissection of these animals shows the presence of young worms in the brain and in the pulmonary arteries. 45 days later, first-stage larvae are recovered from the feces of animals. Now, the strain is maintained in Biomphalaria glabrata and in the rat.

Animals↗
PubMed1998

Malaria, schistosomiasis, and intestinal helminths in relation to microdams in Tigray, northern Ethiopia.

A survey was undertaken in Tigray, Northern Ethiopia, to assess the prevalence of malaria, schistosomiasis, and intestinal helminths in relation to microdams. The survey took place from March to June 1995, during the dry season, at 41 microdams. At each site the village nearest the dam (within thirty minutes walk) was selected, ten households were randomly chosen, and all family members were examined for malaria and intestinal parasites. The overall study sample was 2271 people, of all age groups. Plasmodium falciparum infection was documented in four villages (at 10% of microdams); prevalence was 1.2% (range 0-20% by village). Larvae of Anopheles gambiae s.l. were found at one microdam. Infection with intestinal schistosomiasis was documented in 20 villages (at 49% of microdams), and one third of those infected had moderate to heavy infections. Biomphalaria species, the intermediate host snails of Schistosoma mansoni, were found at 16 microdams (39%), and snails infected by mammalian cercariae were found in one locality. Infections with soil-transmitted nematodes were prevalent: hookworm was detected in more than two thirds of the villages, and Ascaris lumbricoides and Trichuris trichiura were present in almost half of the villages. Out of 2078 stool examinations, the prevalence of S. mansoni infection was 7.2% (range 0-48% by village), of A. lumbricoides 2.3% (range 0-31%), of T. trichiura 2.4% (range 0-21%), and of hookworm 8.9% (range 0-78%). The prevalence of malaria, S. mansoni and hookworm was higher at altitudes below 2000 metres above sea level. S. mansoni was more prevalent in microdams built more than 5 years before the survey, while T. trichiura was more prevalent at recently constructed microdams. The widespread distribution of schistosomiasis and intestinal helminths, and the presence of malaria infection during the dry season confirm that microdams create favourable conditions for the transmission of these parasitic diseases. Health safeguards must be incorporated into the planning, construction, and operation of microdams and irrigation systems in order to prevent or reduce these diseases. In areas with high prevalence, control activities should be intensified.

Adolescent↗
PubMed1999

Schistosomiasis in newly reclaimed areas in Egypt. 2--Patterns of transmission.

The distribution, abundance and seasonality of infected Biomphalaria alexandrina and Bulinus truncatus were studied for 2 years (1992-1994) in two newly reclaimed areas, namely El Manayef and El-Morra areas located on both sides of Suez Canal near Ismailia City. The results confirm the occurrence of transmission of both Schistosoma mansoni and S. haematobium since infected snails of both species were recovered in these areas. This consequently proves that reclamation of parts of the desert utilizing Nile water had led to spread of schistosomiasis to these areas. Analysis of the data shows that the infected snails, especially B. alexandrina, were found clustered in a relatively few numbers of transmission sites and furthermore the greater majority of these sites were found located within a less number of transmission foci. This pattern of focality is clearly demonstrated by Geographical Information System (GIS) produced maps. Infected B. alexandrina snails fluctuated seasonally showing 2 peaks, a minor peak in August and a higher one in November. Only one peak of infected B. truncatus was recognized in July.

Animals↗
PubMedDate not supplied

[Assessment of schistosomiasis and other intestinal parasitoses in school children of the Bambuí municipality, Minas Gerais, Brazil].

This work was carried out with the purpose of determining the prevalence of intestinal parasitoses in the school children of Bambuí, through parasitological examinations (direct and Kato-Katz methods) and reevaluating the snails' breeding places described in the county. Of the 2,091 school children examined, 20.1% had at least one parasitic infection. Giardia lamblia, Entamoeba coli, Ascaris lumbricoides and hookworm are the most frequent parasites, with a prevalence of 6.2%, 6.2%, 4.8% and 1.4%, respectively. The hookworms were significantly more frequent among students from the rural area and in those aged over 14 years, while the prevalence of E. coli was greater in the urban area and the G. lamblia was more frequent in children under 6 years old. Only three children shed eggs of Schistosoma mansoni. The only intermediate host found was Biomphalaria glabrata and none of them was shedding cercariae of S. mansoni. When these data were compared with data from other surveys previously effected in the county, a decline was observed in the prevalence of all parasites. Some hypotheses which may explain this decline are discussed, such as: intense urbanization process and improvement of social-sanitary conditions of the county.

Adolescent↗
PubMedDate not supplied

[Preliminary evaluation of morbidity due to S. haematobium and S. mansoni in the area of the future Adjarala Dam in Benin].

The aim of this study was to provide a preliminary assessment of morbidity due to schistosomiasis in the area of the future Adjarala Dam in Benin. We included 412 schoolchildren from five villages in the study. The mean age of the children was 9.4 +/- 2.3 years and the sex ratio (F/M) was 0.94. These children underwent parasitological examination. The children provided urine samples, which were examined by eye, filtered and tested for blood and protein. Stool samples were examined using Kato's technique and an ultrasound scan of the urinary tract was performed. We carried out a survey of snails at the possible transmission sites of all the villages, with a view to identifying the intermediate hosts. We detected S. mansoni and S. haematobium in the area. Urinary schistosomiasis was mesoendemic (prevalence of 19.7%) whereas schistosomiasis due to S. mansoni was hypoendemic (prevalence of 3. 9%). Ultrasound scans showed that 28% of the children had bladder lesions and that 2.5% were carriers of hydronephrosis. We compared the diagnostic performances of the various indirect indicators of morbidity. We found that a history of hematuria was the most sensitive indicator (88%) but that the sensitivity of this indicator differed significantly according to the sex of the child. Hematuria >= 1+ was the most effective indicator. Snail surveys showed that Biomphalaria pfeifferi and Bulinus globosus were present in the area.

Age Factors↗
PubMedDate not supplied

[Comparative morphofunctional analysis of the gastropod-trematode interactions].

A morphofunctional aspect of pathogenesis in various mollusc--trematode combinations is very different. To evaluate the level of antagonism between the host and parasite, it is reasonable to use a summarized parameter of general physiological state of infected individuals. The somatic growth of the host could be used for that purpose. Analysis of original and reference data has shown, that the gastropod growth response to the trematode infection depends on the longevity of molluscs. The growth acceleration (gigantism) in infected individuals is common for snails with the intermediate longevity (3-4 yr), such as Hydrobia, Onobia and Bithynia (Prosobranchia: Rissoacea). As an exception, the gigantism is observed in the short-living species, which do not change the growth rate when they are parasitized: Biomphalaria, Bulinus, Helisoma and Lymnaea (Pulmonata: Basomathophora). Earlier, it was assumed that the single trend manifested in the infected long-living species (6-27 yr), such as Littorina (Prosobranchia: Littorinacea) and Cerithidea (Prosobranchia: Cerithiacea), in the decrease of the growth rate. The only case of the growth acceleration within the long-living molluscs was detected in the Littorina littorea from the White Sea infected with low pathogenic partenits of Cryptocotyle lingua (Heterophyidae). Based on the groups of snails with different longevity and being phylogenetically distant from each other, we can presume that the growth response to the infection correlates with the morphological peculiarities of hosts. The morphofunctional distinction in the system formed by trematodes and molluscs of different taxa are expressed in the parthenit localization in the host body and in the degree of digestive gland and/or gonad destriction. From the viewpoint of general physiological status of the host organism, the results of disfunctions in these organs are not similar. The destruction of digestive system ("energy power station" of organisms) is more fatal for infected individuals than a parasitic castration. Therefore, the localization of parasites in the mollusc gonad can be recognized as a parasitic adaptation to decrease the probability of a premature host's death and respectively to prevent the elimination of parasites. Phylogenetically distant gastropods with different life cycles use a diverse reproduction strategy, which implies a different proportion of gonad and digestive gland volume. Thus, snail species from different taxa are not similar in relation to the life space, which could be "granted" to the parasite without any risk to reduce a viability of the host. The space lack forces the parthenits parasitizing in the molluscs with the longer life span to occupy the digestive gland tissues, that increases their pathogenicity and decreases the host's growth rate.

Animals↗
PubMedDate not supplied

Occurrence and distribution of fresh-water molluscs in the Riacho Fundo Creek Basin, Brasilia, Brazil.

To study the distribution of molluscs in the Riacho Fundo Creek (cerrado region of central Brazil), five creek sites were sampled once every two months for one year. Molluscs were sampled using standardized kick-net sampling. Four species of molluscs were found: Physella cubensis, Melanoides tuberculata, Biomphalaria straminea and Pisidium sp. The most abundant were P. cubensis and Pisidium sp. Physella cubensis was most abundant in the dry season and Pisidium sp. was most abundant in the rainy season, probably reflecting the rainy season increase of water currents.

Animals↗
PubMedDate not supplied

[Study of the molluscocid properties of lead triphenylacetate].

The molluscicide and biocide properties of lead triphenylacetate (4,5 p p m, on Biomphalaria glabraia and Bulinus contortus) are not so great that the toxic action of tin tributiloxyde, on the same snails (2 p p m). Still the prices of the organic salts of lead are not so expensive as tin organic salts.

Lead↗
PubMed2001

The effect of ecological parameters on the distribution of snail vectors of schistosomiasis.

The infestation of the water courses showed 32.5% for Biomphalaria alexandrina and 8.75% for Bulinus truncatus. Ecological parameters, showed non significant variations in the water courses harbouring snail vectors and those free from snails except for conductivity in the habitats harbouring B. truncatus. This variation was more highly significant (p<0.001). Of the examined sites, 11.25% were harbouring B. alexandrina and Lymnaea natalenesis living together and 5% of the sites were harbouring B. truncatus and Physa acuta snails. Snail vectors were distributed with different degrees with aquatic plants reflecting the degree of species preference plants for snails' life.

Animals↗
PubMed2000

Otoliths developed in microgravity.

Little is known about mechanisms that regulate the development of the otoliths in the gravity-sensing organs. Several reported experiments suggest that the growth of the otoliths is adjusted to produce a test mass of the appropriate weight. If this is the case, larger than normal otoliths would be expected in animals reared in reduced gravity and a reduced mass, relative to 1-g controls, would be expected in animals reared at elevated g. In gastropod mollusks, the gravity-sensing organ is the statocyst, a spherical organ whose wall is made largely of sensory receptor cells with motile cilia facing the lumen. Dense statoconia in the cyst lumen interact with cilia of receptor cells at the bottom of the cyst and action potentials in their axons carry information on direction and magnitude of gravity and linear acceleration. In the marine mollusk, Aplysia californica, larvae reared at 2 to 5-g, the volume of statoconia was reduced in a graded manner, compared to 1-g control animals. In the statocyst of the fresh-water pond snail, Biomphalaria glabrata, reared in space in the Closed Equilibrated Biological Aquatic System (CEBAS), the number and total volume of statoconia was increased approximately 50%, relative to ground-reared controls. Lychakov found the utricular otolith to be 30% larger in space-reared Xenopus, whereas we found the saccular otolith to be significantly larger in newt larvae reared in space. In cichlid fish reared on a centrifuge, the saccular otolith was smaller than in 1-g controls. Here, we demonstrate that the otoliths of late-stage embryos of the swordtail fish, Xiphophorus helleri, reared in space on STS-89 and STS-90 (Neurolab) were significantly larger than those of ground-controls reared in functionally identical hardware.

Animals↗
PubMed2003

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 hosts of Schistosoma sp: Biomphalaria pfeifferi and Bulinus forskalii. However, only the former species was incriminated in the transmission of the disease, with the prevalence of snail infection being 10% (1 of 10) and 14.3% (2 of 14), respectively, during surveys 1 (in the dry season) and 2 (in the rainy season). The overall prevalence of Schistosoma mansoni eggs in stool samples was 54.4% (98 of 180). The mean +/- SD intensity of infection was 100.3 +/- 114.7 eggs per gram of stool. Eggs of S. intercalatum were not detected during parasitologic examination of stool specimens. In Cameroon, it appears that unlike the distribution of S. mansoni, which usually follows that of B. pfeifferi, B. forskalii is commonly found where S. intercalatum does not exist due to competitive exclusion through introgressive hybridization. Of the 180 people included in the study, 52.3% reported abdominal pain and 37.5% had bloody stools. Splenomegaly and hepatomegaly were noted in 11.7% and 3.9%, respectively, of the subjects examined. Three foci of S. mansoni were previously described in the Mbam and Inoubou Division, including Bafia town, Makenene, and Kinding Djabi villages. With the present focus in Yoro, the Mbam and Inoubou Division appears to be the most important endemic zone of S. mansoni in southern Cameroon.

Adolescent↗
PubMed1963

A LARGE-SCALE EXPERIMENT IN THE CONTROL OF AQUATIC SNAILS BY THE USE OF MOLLUSCICIDES ON A SUGAR ESTATE IN THE NORTHERN REGION OF TANGANYIKA.

The author describes a large-scale experiment in which the molluscicide Bayer 73 (Bayluscide) was used in an attempt to eliminate Biomphalaria pfeifferi, the snail host of Schistosoma mansoni, from an irrigation system in Tanganyika. Applied at a concentration of 1 p.p.m., the molluscicide gave a very high kill of snails and much of the treated area remained completely free of vector snails for seven months after treatment. However, there were a few survivors in small pockets associated with a drainage area that became flooded during heavy rains coincident with the application of molluscicide. From these survivors a dramatic resurgence of snails occurred in some of the treated canals. This resurgence may be analogous to similar phenomena observed in some insecticide work. The suggestion is made that removal of parasites and predators, in particular trematode parasites, by a molluscicide might increase the snail's capacity for repopulation. Studies of the seasonal fluctuations of snail population density in an adjacent, but separate, irrigation system suggest that molluscicide applications would be more effective if timed to coincide with the end of the rainy seasons.

Animals↗
PubMed1992

Human helminthosis in a rural community of Plateau State, Nigeria.

Urine and faecal samples were obtained from 1,517 people in Fier, a typical rural village in Plateau State, Nigeria, for a parasitological survey among the population. 643 (42.39%) persons were found to be infected with altogether 9 helminths, namely: Ascaris lumbricoides, hookworm, Taenia sp., Trichuris trichiura, Enterobius vermicularis, Schistosoma mansoni, S. haematobium, Hymenolepis nana and Strongyloides stercoralis. Age and religion as opposed to sex, type of sewage system, and type of housing had a significant effect (P < 0.05) on the prevalence rates of the helminths in the population. Snail vector survey for schistosomatosis revealed the presence of Bulinus (Bulinus) truncatus, Bulinus (Physopsis) globosus and Biomphalaria pfeifferi with the latter being the most common with brevifurcate cercariae, and xiphidiocercariae being the most common cercariae harboured by the snails.

Adolescent↗
PubMed2003

[Transmission of schistosomiasis in an urban population and prevalence of intestinal helminthiasis in Bamako, Mali ].

Parasitological, malacological and anthropological studies were performed to assess the prevalence of Schistosoma haematobium and S. mansoni in schoolchildren living in the suburban area of Bamako. A total of 1017 schoolchildren aged 6-14 years were selected in two different areas between September 1997 and December 1999. In Djikoroni, the prevalence of S. haematobium and S. mansoni was 80.7% (339/420) and 22.8% (85/372) respectively. There was no significant difference of prevalence and intensity of infection with S. haematobium between schools, gender and age (p > 0.05), whereas, those of S. mansoni were higher in the vicinity of (+/- 100 m from) major sites where infected Biomphalaria pfeifferi were found (p < 0.001). In Niomirambougou, S. haematobium was prevalent in 46.7% (279/597) and S. mansoni in 28.2% (134/475). Boys and children aged 11-14 years were more infected (p < 0.001). Associated intestinal helminths (Hymenolepis nana, Necator americanus and Ascaris lumbricoides) were relatively scarce (prevalence < 1%). The prevalences of schistosome infected snails intermediate host were relatively high, 49.3% (100/203) in B. pfeifferi, 20.6% (88/138) in B. truncatus and 24.1% (7/29) in B. globosus. We recorded a total of 2514 water contacts about which 1130 in December and 1384 in January. Most of the children, 42.9% (1077/2511) were attracted to water bodies for bathing, swimming and playing, suggesting the lack of recreational facilities in these areas. Developing local control programmes in schools located in the vicinity of water bodies would contribute to break the parasite transmission cycle in Bamako.

Adolescent↗
PubMed2003

Diagnosis of Fasciola gigantica in snail using the polymerase chain reaction (PCR) assay.

The 124-bp repetitive and highly abundant DNA sequence--used as a specific probe for the detection of Fasciola hepatica infection in snails--was tested in the detection of F. gigantica infection in Lymnaea natalensis. The probe did not show any positive PCR results with Lymnaea natalensis, Physa acuta, Biomphalaria alexandrina and Bulinus trucatus or with Schistosoma mansoni, S. haematobium and Echinostoma liei. However, the probe was found capable to detect F. gigantica infection within L. natalensis at very early stages of the prepatent period and at very low concentrations. Thus, the present assay is specific and sensitive for the detection of F. gigantica within its intermediate host. It confirmed the idea that 124-bp repetitive and highly abundant DNA sequence in Fasciola sp. genome could be used as an epidmiological tool for examination of fasciolosis intermediate host. The nucleic acid-based assay could eliminate both inherent uncertainties and lengthy periods of time required for visual examination of the snails. Also, the assay is valuable in epizootiology of F. gigantica, vector suitability and host-parasite relationship.

Animals↗