Distribuição e diversidade de espécies do gênero Biomphalaria em microrregiões localizadas no Médio Paranapanema, São Paulo, SP, Brasil / Diversity and distribution of the Biomphalaria species in the middle reaches of the Paranapanema River, São Paulo, SP, Brazil

The predominant landscape in the studied region, composed by the Paranapanema and Pardo rivers, has been significantly affected by human interference in order to create extensive artificial irrigation ditches for agriculture. These environments are subject to drastic variations in water supply whereby draughts are created what bears a drastic populational fluctuation. The composition of schistosomiasis-associated planorbid fauna in Ourinhos and Ipauçu herein presented corroborate previous malacological surveys, which incriminates Biomphalaria. glabrata (Say, 1818) as the predominant species mainly at the Ourinhos micro-regions. At this site the snail distribution might be linked to the composition of deposited sediments in the hydrographic basin. Data from Ipauçu, a collection site that is only 30 km from Ourinhos, indicates absence of B. glabrata, and predominance of B. tenagophila (Orbigny, 1835). Despite closeness, the micro-regions show important differences in values of diversity index, indicating a heterogeneous distribution of Biomphalaria species.

Foram estudadas a diversidade e a abundância de espécies do gênero Biomphalaria em córregos próximos aos Rios Paranapanema e Pardo (São Paulo, SP, Brasil), em locais antigamente associados à transmissão do Schistosoma mansoni, sujeitos ainda a drásticas variações na disponibilidade de água. Os dados confirmam a predominância de Biomphalaria glabrata (Say, 1818) em córregos do município de Ourinhos, localizados nas margens do Rio Pardo e do Rio Paranapanema. Em Ipauçu, distante 30 km de Ourinhos, a predominância de Biomphalaria tenagophila (Orbigny, 1835) é acompanhada da ausência de B. glabrata. Foram estimados os índices de Diversidade e Dominância de Simpson, que evidenciam uma distribuição variada, provavelmente associada com o substrato aquático onde vivem os caramujos.

Susceptibility of biomphalaria Alexandria to infection with schistosoma mansoni: Correlation with the activity of certain glycolytic enzymes

The importance of the glycolytic flux for the success of Biomphalaria- Schistosome sporocyst interaction was acertained in this study. Hexokinase [HK], pyruvate kinase [PK], glucose phosphate isomerase [GPI] and lactate dehydrogenase [LD], as four important glycolytic enzymes, were markedly stimulated in trematode infected Biomphalaria alexandrina when measured two weeks post exposure to infection with Schistosoma mansoni miracidia. Treatment with this plant resulted in a significant inhibition of these three investigated enzymes. LC10 concentrations of S. nigrum reduced considerably the infection rate of B. Alexandrina with S. mansoni to be 34% compared to an infection rate of 80% in control, non-treated snails. Susceptibility of B. alexandrina to infection with the digenetic trematode S. Mansoni is correlated to the activity levels of the glycolytic enzymes. Moreover, sublethal and less pollutant concentration of S. Nigrum could be recommended to control schistosomiasis by disturbing the intramolluscan environment of the parasite

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 two years [1992-1994] in two newly reclaimed areas; namely, El-Manayef and El- Morra located on both sides of Suez Canal near Ismailia City. The results confirmed the occurrence of transmission of both Schistosoma mansoni and S. hematobium since infected snails of both species were recovered in these areas. Consequently, this proved that reclamation of parts of the desert utilizing Nile water had led to the spread of Schistosomiasis to these areas. Analysis of the Delta showed that the infected snails, especially B. alexandrina, was found clustered in a relatively few number of transmission sites. Furthermore, the greater majority of these sites were found to be located within a less number of transmission foci. This pattern of focality was clearly demonstrated by geographical information system [GIS] produced maps

Susceptibility of three successive snail generations from positive and negative laboratory bred biomphalaria Alexandrina from different localities in Egypt to infection with schistosoma mansoni from Giza

Susceptibility of snail vectors to schistosome infection varies between geographical areas, population in the same area and among individuals in the same population. It is also affected by biological factors of which are snail size [age], number and age of miracidia exposed to water, temperature, illumination and darkness. The previous studies indicated that snails 4 - 6 mm in diameter exposed to 5 freshly hatched miracidia under light and in water at 25C are optimum conditions for infection of Biomphalaria alexandrina from various localities in Egypt with Schistosoma mansoni [TBRI strain maintained in hamsters]. In the present study, groups of 16 snails from 3 successive generations from positive and negative laboratory bred B. Alexandrina from Giza, Alexandria, Monoufia, Cairo and Menia were exposed to S. mansoni miracidia [TBRI strain] from Giza under the abovementioned optimum conditions. From the 20th day of infection snails were checked from cercariae shedding to estimate the prepatent period and their number from each snail light for one hour. B. alexandrina from the various localities in Egypt were susceptible to S. mansoni [TBRI strain] infection. Snails from Alexandria were the most susceptible, followed by those from Cairo, Giza, Monoufia and Menia. Snails from positive generations were more susceptible to infection than those from negative ones. However, there has been a decline in the susceptibility of snails from one generation to the next

Laboratory study on the molluscicidal effect of earth tec: an environmentally responsible copper sulfate product

Studies were carried out, under laboratory conditions to evaluate the molluscicidal activity of Earth Tec on Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni. Earth Tec is an environmentally responsible copper sulfate product manufactured and marketed as an algicide/bactericide with an active ingredient form of copper ion [Cu++]. A single application of 1 ppm of copper equivalent, for 24 hours caused 100% mortality rate of the snails. Exposure for 48 hours to 1 ppm and 2 weeks to 0.25 ppm caused mortality rates of 84% and 100%, respectively. It was concluded that this chemical compound is a promising molluscicide. Field studies are ongoing and will be published in due time

Suscetibilidade de Biomphalaria tenagophila de Bragança Paulista à cepa de Schistosoma mansoni / Suscetibility of Biomphalaria tenagophila of Bragança Paulista town to infection with Schistosoma mansoni

Estudou-se a suscetibilidade de Biomphalaria tenagophila da regiao de Bragança Paulista (SP) à infecçao progressiva pelo Schistosoma mansoni, cepa SJ. Os resultados pelo Schistosoma mansoni, cepa SJ. Os resultados mostram-se positivos para a infecçao com 100 miracídios. Apenas 50 por cento dos moluscos foram positivos durante 21 dias. Com esses resultados pode-se afirmar que na regiao de Bragança Paulista, com o possível aumento de migraçao de indivíduos da zona endêmica, estamos sujeitos ao aparecimento de casos positivos de esquistossomose adquiridos na regiao.

Population dynamics and schistosomal infection of biomphalaria alexandrina in four irrigation canals in Egypt

The natural growth, reproductivity, mortality and schistosomal infection of Biomphalaria alexandrina, the snail vector of Schistosoma mansoni in Egypt, were studied for one year in four irrigation canals, namely El-Khassa and Radwan [Giza Governorate] and Sendebis and Sanafeer [Qalyoubiya Governorate]. Radwan canal contains a considerably dense Biomphalaria population and three generations of Snails [parents generation and autumn and spring generations] were recognized .Two phases of growth were distinguished in both autumn and spring generations, a faster phase followed by a slower one. The faster phase extends from January to May and from March to August in the autumn and spring generations, respectively. The daily mortality rate of snails was highest in the hot season [June - September] and lowest in the cold months [December - April]. Continuous reproductivity of Biomphalaria snails was observed allover the year with highest values of reproduction index from November to March .Biomphalurza snails collected from El Khassa and Radwan canals were free of S. mansoni infection, while snail of sanafeer canal carried patent infection and September and October. Prepatent infection was also found in Sanafeer canal in July at September and in sendebis canal in September