Influence Of Saccharose On The Development Of Cercariae From Schistosoma Mansoni Strains Bh And Sj.

The development of cercariae from Schistosoma mansoni strains BH and SJ in Biomphalaria glabrata and Biomphalaria tenagophila treated with saccharose was studied. The molluscs were maintained in dechlorinated tap water containing 0.01% saccharose. After one week of treatment with saccharose, B. glabrata and B. tenagophila were exposed to ten S. mansoni miracidia, from BH and SJ strains respectively. Control snails of both species were maintained in dechlorinated tap water without saccharose and exposed to the same number of miracidia. There was no significant difference between the infection rates of snails treated or not with saccharose. However, the two groups of B. glabrata had significantly greater infection rates than the corresponding B. tenagophila groups. Molluscs treated with saccharose had a lower survival rate, with the greatest mortality occurring immediately before and at the beginning of cercariae release. Treatment with saccharose did not result in the release of more cercariae, but larvae from molluscs so treated showed a greater capacity to penetrate mouse skin, which was attributed to the greater energy supply during larval development in the mollusc.651434

A Study Of The Granulomatous Responses Induced By Different Strains Of Schistosoma Mansoni

The increased pathogenesis of the Schistosoma mansoni BH strain compared with the SJ strain has been attributed to the number of granulomas formed in experimental infections, which increase the mortality in definitive hosts. The aim of the present study was to investigate the development of granulomas around the eggs of the S. mansoni BH and SJ strains and to determine whether this host reaction was strain specific. Four experimental groups were analyzed. Two groups contained mice inoculated in the caudal vein with eggs from the S. mansoni BH or SJ strains and the other two contained mice that were infected with cercariae of the BH strain prior to being inoculated with eggs. The number of granulomas per tissue area in the lungs and liver, as well as the size of the granulomas, was analyzed to characterize the response to schistosome infection. The largest granulomatous responses were observed around eggs of the BH strain. Granulomas covered a larger area in the lungs of mice that were previously infected with cercariae and subsequently inoculated with eggs of the BH strain. These results indicated that specific granulomatous responses occurred following an infection with the BH and SJ strains of S. mansoni. © 2012 Nádia Regina Borim Zuim et al.2012Capron, A., Schistosomiasis: Forty years' war on the worm (1998) Parasitology Today, 14 (10), pp. 379-384. , DOI 10.1016/S0169-4758(98)01322-2, PII S0169475898013222Programmes and Projects > Neglected Tropical Diseases, , http://www.who.int/schistosomiasis/en/index.html, World Health Organization-(WHO) 2009Rollinson, D., Southgate, V.R., Rollinson, D., Southgate, V.R., The genus Schistosoma: A taxonomic appraisal (1987) The Biology of Schistosomes from Genes to Latrines, pp. 1-49. , San Diego, Calif, USA Academic PressMagalhães, L.A., Carvalho, J.F., Verificação do número de machos e de fêmeas de Schistosoma mansoni capturados em camundongos infectados com duas cepas do helminto (1969) Revista da Sociedade Brasileira de Medicina Tropical, 3, pp. 253-254Magalhães, L.A., Carvalho, J.F., Desenvolvimento do Schistosoma mansoni das linhagens de Belo Horizonte (MG) e de São José dos Campos (SP) em Mus musculus (1973) Revista de Saúde Pública, 7, pp. 285-287Magalhães, L.A., Carvalho, J.F., Sobre o comportamento de duas linhagens de Schistosoma mansoni Sambon, 1907. Proposição para método de estudo quantitativo (1976) Revista da Sociedade Brasileira de Medicina Tropical, 4, pp. 169-194Paraense, W.L., Corrêa, L.R., Variation in susceptibility of Australorbis glabratus to a strain of Schistosoma mansoni (1963) Revista Do Instituto de Medicina Tropical de Sao Paulo, 5, pp. 15-22. , 2-s2.0-0015152812Lobato Paraense, W., Correa, L.R., Differential susceptibility of Biomphalaria tenagophila populations to infection with a strain of Schistosoma mansoni (1978) Journal of Parasitology, 64 (5), pp. 822-826Saoud, M.F.A., The infectivity and pathogenicity of geographical strains of Schistosoma mansoni (1966) Transactions of the Royal Society of Tropical Medicine and Hygiene, 60 (5), pp. 585-600. , 2-s2.0-0013993940Zanotti-Magalhães, E.M., Magalhães, L.A., Carvalho, J.F., Relação entre a patogenicidade do Schistosoma mansoni em camundongos e susceptibilidade do molusco vetor. II. Número de ovos nas fezes e número e tamanho dos granulomas nas vísceras (1993) Revista de Saúde Pública, 29, pp. 265-270Zanotti-Magalhaes, E.M., Magalhaes, L.A., De Carcalho, J.F., Relationship between the pathogenicity of Schistosoma mansoni in mice and the susceptibility of the vector mollusk. IV - Infectiousness of the miracídia (1997) Revista de Saude Publica, 31 (5), pp. 488-494Coelho, P.M.Z., Raso, P., Mello, R.T., Toppa, N.H., Dimensões do granuloma hepático produzido por ovos de duas linhagens geográficas do Schistosoma mansoni, no camundongo (1989) Memórias Do Instituto Oswaldo Cruz, 84, pp. 213-217Higgins-Opitz, S.B., Dettman, C.D., The infection characteristics of a South African isolate of Schistosoma mansoni: A comparison with a Puerto Rican isolate in BALB/c mice and Mastomys coucha (1991) Parasitology Research, 77 (2), pp. 142-151. , 2-s2.0-0026035421Magalhães, L.A., Carvalho, J.F., Estudo morfológico de Schistosoma mansoni pertencentes a linhagens de Belo Horizonte (MG) e de São José dos Campos (SP) (1973) Revista de Saúde Pública, 7, pp. 289-294Magalhães, L.A., Alcantara, F.G., Carvalho, J.F., Alguns dados referentes ao estudo parasitológico e anatomopatológico de duas linhagens de Schistosoma mansoni, Sambon, 1907 (1975) Revista de Saúde Pública, 9, pp. 1-5Yoshioka, L., Zanotti-Magalhaes, E.M., Magalhães, L.A., Linhares, A.X., Schistosoma mansoni: A study of pathogenesis of Santa Rosa strain (Campinas, SP, Brasil) in mice (2002) Revista da Sociedade Brasileira de Medicina Tropical, 35 (3), pp. 203-207. , 2-s2.0-0036580395Magalhães, L.A., Alcantara, F.G., Carvalho, J.F., Distribuição de lesões esquistossomóticas extra-hepáticas em camundongos infectados pelas linhagens BH e SJ de Schistosoma mansoni (1975) Revista de Saúde Pública, 13, pp. 326-334Zanotti-Magalhães, E.M., Magalhães, L.A., Carvalho, J.F., Relação entre a patogenicidade do Schistosoma mansoni em camundongos e susceptibilidade do molusco vetor. III. Mortalidade, peso corporal e das vísceras (1995) Revista de Saúde Pública, 29, pp. 265-270Dias, L.C.S., Glasser, C.M., Etzel, A., The epidemiology and control of schistosomiasis mansoni where Biomphalaria tenagophila is the snail host (1988) Revista de Saúde Pública São Paulo, 22, pp. 462-463Santos, N.R., (1967) Esquistossomose Mansônica Autóctone No Vale Do Médio Paraíba, Estado de São Paulo, Brasil: Contribuicão Para O Estudo da Zona Endêmica [Ph.D. Thesis], , São Paulo, BrasilKastner, M.R.Q., Kohn, A., Teixeira, E.D., Pitanga, L.C., Estudo morfológico do Schistosoma mansoni Sambon, 1907, encontrado na espécie humana (1975) Revista da Sociedade Brasileira de Medicina Tropical, 9, pp. 247-261MacHado-Silva, J.R., Galvão, C., Presgrave, O.A.F., Rey, L., Gomes, D.C., Host-induced morphological changes of Schistosoma mansoni Sambon, 1907 male worms (1994) Memorias Do Instituto Oswaldo Cruz, 89 (3), pp. 411-416. , 2-s2.0-0028477538MacHado-Silva, J.R., Galvão, C., De Oliveira, R.M., Presgrave, O.A., Gomes, D.C., Schistosoma mansoni Sambon, 1907: Comparative morphological studies of some Brazilian strains (1995) Revista Do Instituto de Medicina Tropical de São Paulo, 37 (5), pp. 441-447. , 2-s2.0-0029367229Machado-Silva, J.R., Lanfredi, R.M., Gomes, D.C., Morphological Study of Adult Male Worms of Schistosoma mansoni Sambon, 1907 by Scanning Electron Microscopy (1997) Memorias do Instituto Oswaldo Cruz, 92 (5), pp. 647-653MacHado-Silva, J.R., Pelajo-Machado, M., Lenzi, H.L., Gomes, D.C., Morphological Study of Adult Male Worms of Schistosoma mansoni Sambon, 1907 by Confocal Laser Scanning Microscopy (1998) Memorias Do Instituto Oswaldo Cruz, 93, pp. 303-307. , 2-s2.0-0032246240Neves, R.H., Dos Santos Pereira, M.J., De Oliveira, R.M.F., Gomes, D.C., MacHado-Silva, J.R., Schistosoma mansoni Sambon, 1907: Morphometric differences between adult worms from sympatric rodent and human isolates (1998) Memorias Do Instituto Oswaldo Cruz, 93, pp. 309-312. , 2-s2.0-0032254332Paraense, W.L., Corrêa, L.R., Observations on two biological races of Schistosoma mansoni (1981) Memorias Do Instituto Oswaldo Cruz, 76 (3), pp. 287-291. , 2-s2.0-0019593327Prata, A., Coura, J.R., Carvalho, O.S., Coelho, P.M.Z., Lenzi, H.L., Fases e formas clínicas da esquistossomose mansoni (2008) Schistosoma Mansoni & Esquistossomose. Uma Visão Multidisciplinar, pp. 739-787. , Rio de Janeiro, Brazil Editora FiocruzMagalhães, L.A., Guaraldo, A.M.A., Zanotti-Magalhães, E.M., Carvalho, J.F., Sgarbieri, V.C., Alcântara, F.G., Esquistossomose mansônica em camundongos experimentalmente subnutridos (1986) Revista de Saúde Pública, 20, pp. 362-368Coutinho, E.M., Malnutrition and hepatic fibrosis in murine schistosomiasis (2004) Memorias do Instituto Oswaldo Cruz, 99 (5), pp. 85-92Lima, E., Costa, M.F., Rocha, R.S., Magalhães, M.H.A., Katz, N., Um modelo hierárquico de análise das variáveis sócio-econômicas e dos padrões de contatos comáguas associados à forma hepatoesplênica da esquistossomose (1994) Cadernos de Saúde Pública, 102, pp. 241-253Dias, L.C.S., Glasser, C.M., Marçal, Jr.O., Bonesso, P.I., Epidemiologia da esquistossomose mansônica em área de baixa endemicidade (1994) Cadernos de Saúde Pública Rio de Janeiro, 12, pp. 254-260Warren, K.S., Domingo, E.O., Cowan, R.B., Granuloma formation around Schistosome eggs as a manifestation of delayed hypersensitivity (1967) American Journal of Pathology, 51 (5), pp. 735-756. , 2-s2.0-0014145729Magalhães, L.A., Technic of viability evaluation of Schistosoma mansoni 's cercariae penetration in Mus musculus (1969) Hospital, 75 (5), pp. 1663-1666. , 2-s2.0-0014514454Warren, K.S., Domingo, E.O., Schistosoma mansoni: Stage specificity of granuloma formation around eggs after exposure to irradiated cercariae, unisexual infections, or dead worms (1970) Experimental Parasitology, 27 (1), pp. 60-66. , 2-s2.0-0014735659Yolles, T.K., Moore, P.V., Degensti, D.L., Ripson, C.A., Meleney, H.E., A technique for the perfusion of laboratory animals for the recovery of schistosomes (1947) Journal of Parasitology, 33. , article 419Institute, S.A.S., (2000) SAS System for Windows, Version 8. 01, , Cary, NC, USALichtenberg, F.V., Host response to eggs of S. mansoni. I. Granuloma formation in the unsensitized laboratory mouse (1962) American Journal of Pathology, 41, pp. 711-731. , 2-s2.0-0000964607Lichtenberg, F.V., Studies on granuloma formation. III. Antigen sequestration and destruction in the schistosome pseudotubercle (1968) American Journal of Pathology, 45, pp. 75-93Ashton, P.D., Harrop, R., Shah, B., Wilson, R.A., The schistosome egg: Development and secretions (2001) Parasitology, 122 (3), pp. 329-338. , DOI 10.1017/S0031182001007351Schramm, G., Gronow, A., Knobloch, J., Wippersteg, V., Grevelding, C.G., Galle, J., Fuller, H., Doenhoff, M.J., IPSE/alpha-1: A major immunogenic component secreted from Schistosoma mansoni eggs (2006) Molecular and Biochemical Parasitology, 147 (1), pp. 9-19. , 2-s2.0-33645846029 10.1016/j.molbiopara.2006.01.003Sadun, E.H., Yamaki, A., Lin, S.S., Burke, J.C., Studies on the host-parasite relationships to Schistosoma japonicum. VI. Acquired resistance in mice and monkeys infected with the Formosan and Japanese strains (1961) The Journal of Parasitology, 47, pp. 891-897. , 2-s2.0-0343097146Mathieson, W., Wilson, R.A., A comparative proteomic study of the undeveloped and developed Schistosoma mansoni egg and its contents: The miracidium, hatch fluid and secretions (2010) International Journal for Parasitology, 40 (5), pp. 617-628. , 2-s2.0-77950023643 10.1016/j.ijpara.2009.10.014Eltoum, I.A., Wynn, T.A., Poindexter, R.W., Finkelman, F.D., Lewis, F.A., Sher, A., Cheever, A.W., Suppressive effect of interleukin-4 neutralization differs for granulomas around Schistosoma mansoni eggs injected into mice compared with those around eggs laid in infected mice (1995) Infection and Immunity, 63 (7), pp. 2532-2536. , 2-s2.0-0029012562Anderson, L., Pierce, R.J., Verjovski-Almeida, S., Schistosoma mansoni histones: From transcription to chromatin regulation: An in silico analysis (2012) Molecular & Biochemical Parasitology, 183, pp. 105-114Bina, J.C., Prata, A., Schistosomiasis in hyperendemic area of Taquarendi. I- Schistosoma mansoni infection and severe clinikal forms (2003) Revista da Sociedade Brasileira de Medicina Tropical, 36 (2), pp. 211-216Zanotti, E.M., Magalhães, L.A., Piedrabuena, A.E., Evaluation of the pathogenicity resulting from infection by Schistosoma mansoni Sambon 1907, agent of unisexual infections in Mus musculus (1983) Revista de Saude Publica, 17 (5), pp. 394-405. , 2-s2.0-0020838115Andrade, Z.A., Warren, K.S., Mild prolonged schistosomiasis in mice. Alterations in host response with time and the development of portal fibrosis (1964) Transactions of the Royal Society of Tropical Medicine and Hygiene, 58 (1), pp. 53-57. , 2-s2.0-000234650

Experimental Evaluation Of The Pathogenicity Of Different Strains Of Schistosoma Mansoni

The pathogenesis of three different Schistosoma mansoni strains from the Brazilian states of Minas Gerais (BH strain) and São Paulo (SJ and SD strains) was evaluated in experimentally infected mice. Observations of the most severe clinical cases among local patients treated (SD strain) in the city of Campinas (São Paulo, Brazil) formed the basis of this study. Mice were used as definitive hosts and were infected with cercariae from Biomphalaria tenagophila (SJ and SD strains) and Biomphalaria glabrata (BH strains). The parameters analyzed were as follows: number of S. mansoni eggs in mice feces; number of granulomas per tissue area in liver, spleen, lungs, pancreas, and ascending colon; measurements of hepatic and intestinal granulomas; number of adult worms; and measurements of trematode eggs. The comparison among the three strains indicated that the SD strain, isolated in Campinas, presented a higher worm recovery relative to the number of penetrating cercariae. In addition, when compared to the SJ and BH strains, the SD strain demonstrated similar pathogenicity to the BH strain, with a greater quantity of granulomas in the viscera, as well as larger granulomas and eggs. Furthermore, a greater quantity of trematode eggs was also shed in the feces. © 2012 Antônio Aurélio Euzébio et al.2012Chieffi, P.P., Waldman, E.A., Aspectos particulares do comportamento epidemiológico da esquistossomose mansônica no Estado de São Paulo (1988) Cadernos de Saúde Pública, 4, pp. 257-275Paraense, W.L., Corrêa, L.R., Sobre a ocorrência de duas raças biológicas do Schistosoma mansoni no Brasil (1963) Ciência e Cultura, 15, pp. 245-246Magalhães, L.A., Carvalho, J.F., Estudo morfológico de Schistosoma mansoni pertencentes às linhagens de Belo Horizonte (BH) e de São José dos Campos (SP) (1973) Revista de Saúde Pública, 7, pp. 289-294Paraense, W.L., Corrêa, L.R., Observations on two biological races of Schistosoma mansoni (1981) Memorias Do Instituto Oswaldo Cruz, 76 (3), pp. 287-291. , 2-s2.0-0019593327Lemos Neto, R.C., Magalhães, L.A., Piedrabuena, A.E., Some aspects concerning the study of strains of Schistosoma mansoni Sambon, 1907, originating from the States of Minas Gerais and São Paulo, Brazil (1978) Revista de Saude Publica, 12 (3), pp. 277-290. , 2-s2.0-0018018745Magalhães, L.A., Alcântara, F.G., Carvalho, J.F., Distribuição de lesões esquistossomóticas extra-hepáticas em camundongos infectados pelas linhagens BH e SJ de Schistosoma mansoni (1975) Revista de Saúde Pública, 13, pp. 326-334Magalhães, L.A., Carvalho, J.F., Sobre o comportamento de duas linhagens de Schistosoma mansoni Sambon, 1907. Proposição para método de estudo quantitative (1976) Revista da Sociedade Brasileira de Medicina Tropical, 10, pp. 169-194Santos, N.R., (1967) Esquistossomose Mansônica Autóctone No Vale Do Médio Paraíba, Estado de São Paulo, Brasil: Contribuição Para O Estudo da Zona Endêmica [Ph.D. Thesis], , São Paulo, Brasil School of Medicine, University of São PauloPiza, J.T., Ramos, A.S., Os focos autóctones da esquistossomose no Estado de São Paulo Arquivos de Higiene e Saúde Pública, 25 (86), pp. 261-271Freitas, A.R.R., Oliveira, A.C.P., Schistosomal myelopathy and the relevance of Schistosomiasis in a low-prevalence area Proceedings of the 8th International Symposium on Schistosomiasis 2002 Recife, BrazilFreitas, A.R.R., Yokoda, J.C.R., Santos, A.M., Reis, R.D., Neumann, M.M.A.G.L., Yamanaka, A., Approach to hepatic alterations in Schistosomiasis in areas of low prevalence by ultrasonography using WHO standardization Proceedings of the 8th International Symposium on Schistosomiasis 2002 Recife, BrazilMagalhães, L.A., Technic of viability evaluation of Schistosoma mansoni 's cercariae penetration in Mus musculus (1969) Hospital, 75 (5), pp. 1663-1666. , 2-s2.0-0014514454Katz, N., Chaves, A., Pellegrino, J., A simple device for quantitative stool thick-smear technique in Schistosomiasis mansoni (1972) Revista Do Instituto de Medicina Tropical de Sao Paulo, 14 (6), pp. 397-400. , 2-s2.0-0015423525Yolles, T.K., Moore, D.U., De Ginsti, D.L., Ripson, C.A., Meleney, H.E., A technique for the perfusion of laboratory animals for the recovery of Schistosomes (1947) Journal of Parasitology, 33, pp. 419-426Institute, S., (2006) SAS System for Windows Versão 9. 01, , Cory, NC, USASaoud, M.F.A., The infectivity and pathogenicity of geographical strains of Schistosoma mansoni (1966) Transactions of the Royal Society of Tropical Medicine and Hygiene, 60 (5), pp. 585-600. , 2-s2.0-0013993940Bina, J.C., Prata, A., Schistosomiasis in hyperendemic area of Taquarendi. I- Schistosoma mansoni infection and severe clinikal forms (2003) Revista da Sociedade Brasileira de Medicina Tropical, 36 (2), pp. 211-216Zanotti-Magalhães, E.M., Magalhães, L.A., Carvalho, J.F., Relação entre a patogenicidade do Schistosoma mansoni em camundongos e a susceptibilidade do molusco vetor. II. Número de ovos nas fezes e número e tamanho dos granulomas nas vísceras (1993) Revista de Saúde Pública, 27, pp. 412-420Zanotti-Magalhães, E.M., Magalhães, L.A., Carvalho, J.F., Relação entre a patogenicidade do Schistosoma mansoni em camundongos e a susceptibilidade do molusco vetor. III. Mortalidade, pesos corporal e das vísceras (1995) Revista de Saúde Pública, 29, pp. 265-270Yoshioka, L., Zanotti-Magalhaes, E.M., Magalhães, L.A., Linhares, A.X., Schistosoma mansoni: A study of pathogenesis of Santa Rosa strain (Campinas, SP, Brasil) in mice (2002) Revista da Sociedade Brasileira de Medicina Tropical, 35 (3), pp. 203-207. , 2-s2.0-0036580395De Abreu Ferrari, T.C., Involvement of central nervous system in the schistosomiasis (2004) Memorias do Instituto Oswaldo Cruz, 99 (5), pp. 59-62Stadecker, M.J., The development of granulomas in schistosomiasis: Genetic backgrounds, regulatory pathways, and specific egg antigen responses that influence the magnitude of disease (1999) Microbes and Infection, 1 (7), pp. 505-510. , 2-s2.0-0032717153 10.1016/S1286-4579(99)80089-

Relationship Between The Pathogenicity Of Schistosoma Mansoni In Mice And The Susceptibility Of The Vector Mollusk. Iii. Mortality, Body And Viscera Weight [relacao Entre A Patogenicidade Do Schistosoma Manoni Em Camundongos E A Susceptibilidade Do Molusco Vetor. Iii. Mortalidade, Pesos Corporal E Das Visceras.]

The relationship between the development of hepatomegaly, splenomegaly, body weight and mortality rate and the degree of susceptibility of Biomphalaria glabrata and B. tenagophila at which infective cercariae developed was studied. The study utilized Swiss mice, SPF, as definitive hosts and populations of snails genetically selected for character susceptibility as intermediate hosts. Low body weight and smaller viscera were observed in infected mice with cercariae originating from snails that showed a high degree of susceptibility. The higher susceptibility of molluscs infected with S. mansoni corresponded to a lower survival of the infected mice. These results lead to the conclusion that the higher degree of adaptation of the parasite to its intermediate hosts, evidenced by the high indexes of susceptibility, leads to different behaviour on the part of this parasite in its definitive host.29426527

Relationship Between The Pathogenicity Of Schistosoma Mansoni In Mice And The Susceptibility Of The Vector Mollusc. I. Cercariae Infectivity And Worm Burden [relação Entre A Patogenicidade De Schistosoma Mansoni Em Camundongos E A Susceptibilidade Do Molusco Vetor. I. Infecciosidade Das Cercárias E Carga De Vermes.]

The possible influence of the immune mechanisms of the molluscs on the development of the sporocysts and the resultant behavior of the adult worm in the vertebrate host were studied. Two strains of Schistosoma mansoni (BH and SJ) were used. These were genetically selected for their susceptibility and maintained, respectively, in Biomphalaria glabrata and Biomphalaria tenagophila, the natural invertebrate hosts. Experimental groups of mice infected with cercariae proceeding from the two species of molluscs, belonging to generations P, F1, F2, F3 and F4, were formed. The infection rates of the snails, the number of the penetrant cercariae and the worm burden in mice were evaluated. It was concluded that the higher susceptibility of Biomphalaria tenagophila results in a greater ability on the part of the cercarial to develop into adult worms. The higher susceptibility of B. glabrata results in greater power of penetration into mice tegument on the part of the cercariae.25535936

Relationship Between The Pathogenicity Of Schistosoma Mansoni In Mice And The Susceptibility Of The Mollusk Vector. Ii. Number Of Eggs In Feces And Number And Size Of Granuloma In Visceras [relação Entre A Patogenicidade Do Schistoma Mansoni Em Camundongos E A Susceptibilidade Do Molusco Vetor. Ii. Número De Ovos Nas Fezes E Número E Tamanho Dos Granulomas Nas Vísceras.]

The influence of the susceptibility of the vector snails of S. mansoni on the development of the pathogenicity of the worm to the host was studied. Off-spring of snails Biomphalaria glabrata and Biomphalaria tenagophila were used, selected with regard to the susceptibility to S. mansoni of the strains BH and SJ trait, respectively. Parenteral, F1, F2, F3 and F4 generation cercariae were used for the infection of Swiss mice, which were killed eight weeks after infection. The number of eggs in the feces and the number of granulomas in the liver, spleen and intestines were counted. The size of the granulomatous reactions was evaluated. The results led to the conclusion that greater susceptibility of B. tenagophila was associated with a larger egg production in the feces and a higher density of granulomas in the liver. There is a clear inverse relationship between the area of hepatic, splenic and intestinal granulomas and the rate of infection of the snails which served as intermediate hosts for the S. mansoni.27641242

Miracidial Attraction By Biomphalaria Tenagophila Genetically Selected For Susceptibility [atração Miraxonal Exercida Por Biomphalaria Tenagophila Selecionada Geneticamente Para O Caráter Susceptibilidade.]

The attraction of Schistosoma mansoni miracidea by snails genetically selected for susceptibility to infection is considered. Miracidea were exposed to snails or to snail conditioned water in a specially devised three-chamber glass apparatus. Ten miracidea were used for each test and were deposited in the middle chamber (a passage); after 15 minutes, them in each of the number of the three chambers were recorded. In one of the chambers, chosen randomly at each trial, either snails or SCW were used. The snails and the SCW were chosen from either selected snails (highly susceptible) or unselected. The miracidea were of two groups: they came either from susceptible snails in previous generation or were of unselected traits. The results show that only snail generation has importance for the attraction: selected molluscs of susceptible traits do attract the miracidea more.252134138EPSRC; Engineering and Physical Sciences Research Counci