RESUMO
The construction of the Diama dam on the Senegal river, the Manantali dam on the Bafing river, Mali and the ensuing ecological changes have led to a massive outbreak of Schistosoma mansoni in Northern Senegal, associated with high intensity of infections, due to intense transmission, and the creation of new foci of S. haematobium. Data on the vectorial capacity of Biomphalaria pfeifferi from Ndombo, near Richard Toll, Senegal are presented with sympatric and allopatric (Cameroon) S. mansoni. Comparisons are made on infectivity, cercarial production, chronobiology of cercarial emergence and longevity of infected snails. Recent data on the intermediate host specificity of different isolates of S. haematobium from the Lower and Middle Valley of the Senegal river basin (SRB) demonstrate the existence of at least two strains of S. haematobium. The role of Bulinus truncatus in the transmission of S. haematobium in the Lower and Middle Valleys of the SRB is reviewed. Both S. haematobium and S. mansoni are transmitted in the same foci in some areas of the SRB.
Assuntos
Água Doce/parasitologia , Schistosoma haematobium/isolamento & purificação , Schistosoma mansoni/isolamento & purificação , Esquistossomose Urinária/transmissão , Esquistossomose mansoni/transmissão , Animais , Biomphalaria/parasitologia , Biomphalaria/fisiologia , Bulinus/parasitologia , Bulinus/fisiologia , Surtos de Doenças , Vetores de Doenças , Humanos , Schistosoma haematobium/fisiologia , Schistosoma mansoni/fisiologia , Esquistossomose Urinária/epidemiologia , Esquistossomose mansoni/epidemiologia , Senegal/epidemiologiaRESUMO
The construction of the Diama dam on the Senegal river, the Manantali dam on the Bafing river, Mali and the ensuing ecological changes have led to a massive outbreak of Schistosoma mansoni in Northern Senegal, associated with high intensity of infections, due to intense transmission, and the creation of new foci of S. haematobium. Data on the vectorial capacity of Biomphalaria pfeifferi from Ndombo, near Richard Toll, Senegal are presented with sympatric and allopatric (Cameroon) S. mansoni. Comparisons are made on infectivity, cercarial production, chronobiology of cercarial emergence and longevity of infected snails. Recent data on the intermediate host specificity of different isolates of S. haematobium from the Lower and Middle Valley of the Senegal river basin (SRB) demonstrate the existence of at least two strains of S. haematobium. The role of Bulinus truncatus in the transmission of S. haematobium in the Lower and Middle Valleys of the SRB is reviewed. Both S. haematobium and S. mansoni are transmitted in the same foci in some areas of the SRB
Assuntos
Humanos , Animais , Barragens , Água Doce/parasitologia , Schistosoma haematobium/isolamento & purificação , Schistosoma mansoni/isolamento & purificação , Esquistossomose Urinária/transmissão , Esquistossomose mansoni/transmissão , Biomphalaria/parasitologia , Biomphalaria/fisiologia , Bulinus/parasitologia , Bulinus/fisiologia , Surtos de Doenças , Schistosoma haematobium/fisiologia , Schistosoma mansoni/fisiologia , Esquistossomose Urinária/epidemiologia , Esquistossomose mansoni/epidemiologia , SenegalRESUMO
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.
Assuntos
Bulinus/efeitos dos fármacos , Bulinus/parasitologia , Euphorbiaceae , Látex/farmacologia , Extratos Vegetais/farmacologia , Esquistossomose Urinária/transmissão , Esquistossomose mansoni/transmissão , Animais , Bioensaio , Diterpenos/farmacologia , Embrião não Mamífero/efeitos dos fármacos , Oócitos/efeitos dos fármacos , Esquistossomose Urinária/prevenção & controle , Esquistossomose mansoni/prevenção & controleRESUMO
A detailed knowledge of distribution patterns of schistosome intermediate hosts and their population dynamics and factors affecting these patterns will provide useful information about the possibilities and desirability of conducting snail control measures in various transmission situations. On the basis of various case studies the association between the occurrence of human water contacts and the presence of schistosome intermediate hosts or infections in the intermediate hosts is illustrated. Other parameters affecting snail distribution patterns and density fluctuations are discussed. It is concluded that ecological studies on the intermediate hosts are extremely relevant, either to optimally apply existing control measures or to develop alternative measures of snail control, such as ecological or biological control.