Direct assessments of gene function in parasitic flatworms have been hampered by the lack of effective tools to alter gene expression. The aim of the present study was to use RNA-interference (RNAi) to achieve targeted gene knockdown in larval stages of the human blood fluke, Schistosoma mansoni. We selected two S. mansoni genes for RNAi experiments: SGTP1, a facilitated diffusion glucose trans...

Experimental infections of Lymnaea columella with Fasciola hepatica were carried out to test the effect of sympatric and allopatric combinations between parasite and host, by using snails and flukes from southern and south-eastern Brazil. Four groups of 50 snails were infected with four miracidia per snail: two groups in sympatric and two groups in allopatric combinations. Sympatric combination...

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 respecti...

The efficacy of praziquantel for the treatment of Schistosoma japonicum in humans is reported from a cross-sectional survey conducted in 33 villages in Sichuan Province. Infection prevalence was found to be 5.7% (185 infected of 3,269 tested) in a region where 44-73% prevalence was found 9 years before. Collected miracidia were subjected to an in vitro test of praziquantel susceptibility. An ef...

Infectivity, development, and growth of Zygocotyle lunata in 18 male Balb/c mice, each exposed to 20 metacercariae cysts, were examined 1 to 6 wk post-infection (PI). Metacercariae cysts were obtained from naturally infected Helisoma trivolvis snails. At necropsy, 11 of 18 mice were found infected with a total of 32 worms. The range of recovery was 1 to 6 worms per host. The mean body area of w...

BACKGROUND Trematodes belonging to the genus Schistosoma cause schistosomiasis. The relationship between schistosomes and their intermediate hosts varies among snails. This study investigated the effects of S. japonicum on its snail host, Oncomelania hupensis, and cercarial release rythmicity of S. japonicum and the effects of light on it. METHODS Seven groups of O. hupensis (n = 40 each) wer...

Fascioliasis is a parasitic disease of domestic ruminants that occurs worldwide. The lymnaeid intermediate hosts of Fasciola hepatica include Lymnaea columella, which is widely distributed in Brazil. A colony of L. columella from Belo Horizonte, MG, was reared in our laboratory to be used in studies of the F. hepatica life cycle, the intermediate host-parasite relationship and development of an...