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

Souza, de; Lk, Jannotti-Passos; Freitas, de

doi:10.1590/s0074-02761995000100003

Cited by 29 publications

(19 citation statements)

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“…Compatibility Index assessments using three strains of S. mansoni Table 1 Molluscicidal activity of commercial ivermectin (a mixture of ivermectin B 1a (1) and B 1b (2)) against B. glabrata, B. tenagophila and B. straminea (LE, SJ and AL) demonstrating that B. straminea displays by far the lowest levels of infection. 20 We found ivermectin to be less potent than previously reported, B. glabrata appearing 5-fold less susceptible to ivermectin in comparison with the data presented by Matha and Weiser. It is therefore important to emphasize our finding that only one of the two constituents of IVM appears to have molluscicidal properties.…”

Section: Discussionsupporting

confidence: 70%

Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis

et al. 2017

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The impact of ivermectin on adult snails of the genus Biomphalaria (B. glabrata, B. tenagophila and B. straminea), B. glabrata infected with Schistosoma mansoni, snail egg-masses cercariae and miracidia, as well as on guppy fish (Poecilia reticulata) was examined and evaluated. Biomphalaria snails, egg-masses, parasite stages and guppies were all exposed to different concentrations of ivermectin for 24 h, followed by regular observations of mortality. The calculated lethal doses of ivermectin were around an LD 50 of 0.03 μg ml − 1 , and an LD 90 of 0.3 μg ml − 1 for the three species of snails. Specimens of B. glabrata actually shedding parasite cercariae all died when exposed to ivermectin at a concentration of a mere 0.01 μg ml − 1 . Ivermectin B 1a , the major (80%) component of commercially available ivermectin, proved to be inactive, and it was the minor (20%) component, ivermectin B 1b , which caused snail death. Snail egg-masses were not affected, even at the highest concentration of 100 μg ml − 1 . With respect to S. mansoni parasite stages, 0.2 μg ml − 1 ivermectin killed 50% of cercariae and miracidia within five minutes, rising to 90% after 30 min. Mortality of guppy fish within 24 h of exposure to ivermectin at concentrations of 0.5 μg ml − 1 and 0.01 μg ml − 1 , were 100% and 30%, respectively. The concentration of 0.01 μg ml − 1 that killed Schistosoma mansoni-infected snails only caused 30% mortality in guppy fish. Ivermectin can be considered a promising molluscicide, especially as it is more potent against infected snails than uninfected ones, although it has no impact on egg-masses. Ivermectin and its derivatives could be explored in the search for a new agent to help control schistosomiasis transmission.

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Section: Discussionsupporting

confidence: 70%

Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis

et al. 2017

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“…Parasites and hosts -The S. mansoni (LE strain) life cycle was maintained using B. glabrata (Barreiro de Cima strain) snails as intermediate hosts and Swiss mice as definitive hosts, according to Pellegrino and Katz (1968) and Souza et al (1995).…”

Section: Subjects Materials and Methodsmentioning

confidence: 99%

“…Thirty days post-infection the snails were exposed to ar-tificial light for 1 h to verify the shedding of cercariae (Souza et al 1995). The snails shedding cercariae were divided into two groups (infected snail or infected snails treated with PZQ).…”

Section: Subjects Materials and Methodsmentioning

confidence: 99%

Schistosoma mansoni: a method for inducing resistance to praziquantel using infected Biomphalaria glabrata snails

Couto

Coelho

Araújo

et al. 2011

Mem. Inst. Oswaldo Cruz

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115

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To elucidate the mechanisms of antischistosoma resistance, drug-resistant Schistosoma mansoni laboratory isolates are essential. We developed a new method for inducing resistance to praziquantel (PZQ) The current strategy for schistosomiasis control is based on large-scale treatments of populations aimed at reducing disease morbidity (WHO 2002). Currently, praziquantel (PZQ) is the drug of choice (Utzinger & Keiser 2004, Fenwick & Webster 2006, with the main advantages of its use being oral administration, single dose, low toxicity and low cost (Fenwick et al. 2003, Utzinger & Keiser 2004. Despite the advantages of PZQ, there is concern about the development of Schistosoma mansoni resistance to PZQ, both under laboratory and field conditions (Abdul-Ghani et al. 2009). In the laboratory, induction of resistance is based on the treatment of mice infected with S. mansoni, initially using sub-curative doses of PZQ. Afterwards, the dosage is increased for at least seven passages in mice/snails to complete the life cycle of the parasite (Ismail et al. 1994, Fallon et al. 1995.The complete mechanism of action of PZQ is still unclear (Doenhoff et al. 2008). Obtaining resistant strains is important for the evaluation of such mechanisms as well as for the development of alternative drugs for schistosomiasis treatment and control. Studies show that PZQ is effective not only in adult worms, but also in the intramolluscan phase of the parasite (Coelho et al. 1988. We report a novel meth- od for the induction (or selection) of S. mansoni worms resistant to PZQ using successive treatments of infected Biomphalaria glabrata snails. SUBJECTS, MATERIALS AND METHODSParasites and hosts -The S. mansoni (LE strain) life cycle was maintained using B. glabrata (Barreiro de Cima strain) snails as intermediate hosts and Swiss mice as definitive hosts, according to Pellegrino and Katz (1968) and Souza et al. (1995).Perfusion of adult worms from infected mice -Two methods were used. The methodology described by Pellegrino and Siqueira (1956) used a needle attached to a Brewer's automatic pipetter to inject saline solution under pressure into the descendent aorta. Afterwards, saline was injected into the hepatic hilum of mice after sectioning the portal vein, allowing the perfusion of the portal system and mesenteric veins. Worms were recovered and counted. To recover the worms using the methodology described by Smithers and Terry (1965) the portal vein of the mice was sectioned and the culture medium was gently injected into the base of the left ventricle of the infected mice's hearts. It is not possible to recover all the worms using this methodology with a lower pressure injection, but the integrity of the parasite's tegument is preserved. Therefore, this methodology is ideal for the recovery of worms when the goal is to cultivate or evaluate other parameters such as tegumental integrity and/or excretory activity.Induction of resistance to PZQ in the intramolluscan phase -Two-hundred B. glabrata were individually infected with 10 S. man...

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“…Differences in susceptibility/resistance occur not only intraspecifically (Souza et al 1995b), but have been demonstrated between different snail species, such as B. glabrata, B. tenagophila and B. straminea (Barbosa 1975, Souza et al 1995a.…”

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confidence: 99%

Histopathologic features associated with susceptibility and resistance of biomphalaria snails to infection with Schistosoma mansoni

Borges

Souza

Andrade

1998

Mem. Inst. Oswaldo Cruz

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Resistance and susceptibility of Biomphalaria snails to Schistosoma mansoni sporocysts occur in different degrees. Histopathology reflects these diferences. In a state of tolerance numerous sporocysts in different stages of differentiation are seen in the absence of host tissue reaction. However extensive diffuse and focal proliferation of amebocytes with sequestration and destruction of many parasitic structures appear in resistant snails. Some snails are totally resistant and when exposed to infecting miracidia may never eliminate cercarie. Sequential histopathological examination has revealed that in such cases the infected miracidia are destroyed a few minutes to 24 hr after penetration in the snail. However, B. glabrata that were exposed to S. mansoni miracidia and three moths later failed to shed cercariae, exhibited focal and diffuse proliferation of amebocytes in many organs in the absence of pasitic structures. These lesions were similar to those observed in resistant snails that were still eliminating a few cercariae, with the difference that no recognizable sporocystic structures or remmants were present. Histological investigation carried out in similarly resistant B. tenagophila and B. straminea presented essentially normal histologic structures. Only occasionally a few focal proliferative (granulomatous) amebocytic reactions were seen in ovotestis and in the tubular portion of the kidney.Probably, there are two types of reactions to miracidium presented by totally resistant snails: one would implicate the immediate destruction of the miracidium leaving no traces in the tissues; the other involving late reactions that seem to completely destroy invading sporocysts and leave histological changes.

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

Cited by 29 publications

References 0 publications

Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis

Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis

Schistosoma mansoni: a method for inducing resistance to praziquantel using infected Biomphalaria glabrata snails

Histopathologic features associated with susceptibility and resistance of biomphalaria snails to infection with Schistosoma mansoni

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