Degree of host-parasite compatibility between Schistosoma mansoni and their intermediate molluscan hosts in Brazil

The compatibility of Biomphalaria tenagophila, B. straminea and B. glabrata from Minas Gerais with different strains of Schistosoma mansoni was evaluated using the method of Frandsen (1979b) in standardized experiments. One hundred and fifty of each species of snail were individually exposed in the laboratory to 50 miracidia of S. mansoni lines LE, SJ and AL. The cercariae from the infected snails were counted and used to calculate TCP/100 indices, which were compared with those of Frandsen (1979b). For B. tenagophila the TCP/100 indices varied from 37,996 to 74,266 (class II and III). The snail was poorly compatible with LE (class II) and compatible with SJ and AL (class III). For B. straminea the indices varied from 9,484 to 20,508. The snail was not very compatible with SJ (class I) and poorly compatible with LE and AL (class II). For B. glabrata the indices varied from 588,828 to 1,039,065. The snails was extremely compatible (class VI) with the three lines of S. mansoni. These results confirm the epidemiological importance of B. glabrata in Brazil followed by B. tenagophila and B. straminea

Diagnostic of Biomphalaria snails and Schistosoma mansoni: DNA obtained from traces of shell organic materials

Freshwater snails belonging to the genus Biomphalaria act as intermediate hosts for the parasite trematode Schistosoma mansoni in Africa and in the neotropical region. Identification of such molluscs is carried out based on morphological characters and the presence of cercariae is verified through squeezing snails between two glass slides or by exposing them to artificial light. However, sometimes, the material collected includes molluscs with decomposed bodies or, yet, only empty shells, which precludes their identification and S. mansoni detection. Due to these difficulties, we have developed a methodology in which DNA may be extracted from traces of organic material from inside shells in order to identify molluscs through polymerase chain reaction and restriction fragment length polymorphism and to detect S. mansoni into these snails, by using low stringency polymerase chain reaction. Species-specific profiles obtained from B. glabrata, B. straminea, and B. tenagophila snails and their shells, maintained in laboratory for ten years, showed the same profiles. S. mansoni profiles showed to be present in shell specimens as far as the eighth week after being removed from aquarium

Influência da temperatura sobre o desenvolvimento da cercária fêmea de Schistosoma mansoni em Biomphalaria glabrata

In these experiments the ratio of male to female S. mansoni larvae in D. glabrata from Belo Horizonte and Ribeirão das Neves Minas Gerais, Brazil, either reared in laboratoty or collected in the field, varied from 1:1 to 1:1.3 or 1.4:1. Cercariae of LE strain of Schistosoma mansoni, shed by 39 snails maintained at 25±0.5ºC were used to infect mice on a weekly basis. Subsequent perfusion resulted in 76.6% male and 23.4% female worms. The cercariac produced by 32 infected snails maintained at 27+0.5°C were inoculated into mice and produced 43.4% male and 56.6% female worms (pNestes experimentos a relação de larvas de Schistosoma mansoni, macho e fêmea, em Biomphalaria glabrata de Belo Horizonte e de Ribeirão das Neves, MG, Brasil, criada no laboratório ou capturada no campo variou de 1:1 a 1: 1 ,3 ou 1,4:1. Cercánas de 39 moluscos mantidos a 25 ± 0,5°C, inoculadas em camundongos originaram 76,6% de vermes machos e 23,4% de fêmeas; cercárias de 32 exemplares mantidos a 27 ± 0,5°C, originaram 43,4% de vermes machos e 56,6% de fêmeas (

Schistosoma mansoni: relação de vermes machos e fêmeas em animais inoculados com cercárias de três espécies de Biomphalaria

The ratios of male to female worms of Schistosoma mansoni were determined in mice infected with cercariae from LE, SJ and AL strains shed by mollusc hosts of the parasite in Brazil. The sex ratios of worms in the animals were similar with cercariae from Biomphialaria glabrata and B. tenagophila varying from 1.1:1 to 1.6:1 with LE and AL strains and 1:1.1 with SJ. In the animals infected with cercariae from B. straminea the ratio of male to female worms was similar to those obtained using cercariae shed from the other two species of molluscs, 1.5:1 with LE strain. Inoculations by AL and SJ cercariae resulted in sex ratios of 3.1:1 and 6:1 respectively. The normal sex ratios of worms established in Brazil in animals inoculated with cercariae from B. glabrata and B. tenagophila is from 1:1 to 2:1. The higher number of male worms that developed from cercariae of the AL and SJ strains obtained from B. straminea indicate a lower compatibility of the snail concerning these strains of S. mansoni.A relação de vermes machos e fêmeas de Schistosoma mansoni foi determinada em camundongos infectados com cercárias das cepas LE, SJ e AL, eliminadas pelos moluscos hospedeiros do parasita no Brasil. Os números de vermes machos e fêmeas recuperados em inoculações de cercárias provenientes de Biomphalaria glabrata e B. tenagophila, foram semelhantes, variando de 1,1:1 a 1,6:1 com LE e AL e de 1:1,1 com SJ. Nos animais inoculados com cercárias provenientes de B. straminea a relação de vermes macho e fêmea foi semelhante à obtida com cercárias provenientes das outras duas espécies com a cepa LE, relação de 1,5:1. Nas inoculações de cercárias de AL e SJ provenientes de B. straminea a relação foi de 3,1:1 e 6:1, respectivamente. A relação normal de vermes macho para fêmea registrada no Brasil, em inoculações de cercárias de B. glabrata e B. tenagophila, é de 1:1 a 2:1. O grande número de vermes machos provenientes de cercárias das cepas AL e SJ eliminadas por B. straminea mostrou a compatibilidade menor do molusco com essas cepas de S. mansoni

Schistosoma mansoni: níveis de infecciosidade para os moluscos hospedeiros intermediários do Brasil

Os níveis de infecciosidade de Schistosoma mansoni para as três espécies de Biomphalaria, hospedeiras intermediárias do parasita no Brasil, foram pesquisados após exposições conjuntas dos moluscos a miracídios, no laboratório e no campo. Foram utilizadas as cepas LE e SJ de S. mansoni, mantidas no laboratório e WVS e RFS obtidas de fezes de escolares de Belo Horizonte, MG. Os resultados mostraram a infecciosidade maior de S. mansoni para B. glabrata, com taxas de infecção de 4, 7 a 85,5%. A B. straminea foi suscetível às cepas LE, SJ e WVS, com taxas de infecção de 11,0 a 24,6%. A B. tenagophila foi suscetível a LE e Sj com taxas de infecção de 2,5 a 6,5%. As médias de cercárias da cepa WVS, eliminadas por dia por B. straminea e B. glabrata variaram de 93 ± 59 e 782 ± 1.120, respectivamente.<br>The levels of infectivity of Schistosoma mansoni for the three species of Biomphalaria, intermediate hosts of parasite in Brazil were studied after exposing of molluscs to miracidia in the laboratory and in the field. The LE and SJ strains of S. mansoni, maintained in laboratory were used in these experiments as well as the WVS and RFS strains ohtained from faeces of schoolchildren from Belo Horizonte, MG. The results show the high level of infectivity of S. mansoni for B. glabrata with infection rates varying from 4.7 to 85-5%. The snail B. straminea was susceptible to LE, SJ and WVS strains, with infection rates of 11.0 to 24.6%, B. tenagophila was susceptible only to LE and SJ strains with infection rates of 2.5 to 6.5%. The mean number of cercariae of the WVS strain shed per day, by B. straminea and B. glabrata were 93 ± 59 and 782 ± 1,120, respectively

Sarasinula marginata (Semper, 1885) (Mollusca, Soleolifera) de Belo Horizonte (MG, Brazil) como hospedeira intermediária potencial do Angiostrongylus costaricencis Morera & Céspedes, 1971

Specimens of Sarasinula marginata were collected in kitchen and house gardens of Belo Horizonte, Minas Gerais. The suscetibility of these molluscs for Angiostrongylus costaricensis was tested by infecting 15 laboratory - reared slugs (F1). The positivity demonstrated was of 80.0%.Espécimes de Sarasinula marginata foram coletadas em hortas e jardins residenciais de Belo Horizonte, Minas Gerais. A suscetibilidade desta espécie de lesma ao Angiostrongylus costaricensis foi verificada em laboratório, utilizando-se 15 exemplares da geração F1. Foi demonstrada uma positividade de 80,0