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PubMed1957

Intermediate hosts of schistosoma: African Biomphalaria and Bulinus. II.

This study is an attempt to classify all described species of African Bulinus. It is based upon the author's examination of a great number of specimens collected from many parts of Africa. The variations attributable to age, environment and genetic factors which may be noted in the taxonomic characters are discussed, and some new species and subspecies are established. For each recognized species and subspecies the author states the distinguishing characters, indicates the geographical distribution, and gives a list of synonyms.

Africa↗
PubMed2003

Difference in the susceptibility to certain molluscicides and Schistosoma mansoni infection of three forms Egyptian Biomphalaria glabrata.

The first generation of 3 morphologically different forms of B. glabrata collected from Giza were compared for LC50 values susceptibility to bayluscide and copper sulphate (chemical molluscicides) and Anagallis arvensis and Calendula micrantha (plant molluscicides) and to Schistosoma mansoni infection. Form (2) as juvenile and adult were less sensitive to C. micrantha and A. arvensis. Form (3) as juvenile and form (1) as adult were least sensitive to CuSO4. Approximately the same susceptibility to bayluscide was observed in the 3 forms either as juvenile or adult. The sublethal concentrations of the molluscicides on B. glabrata 3 forms showed no significant difference in the growth or survival rate in between. Form (2) was significantly higher in the egg lying capacity. The total protein concentration was not affected except in certain cases where the increase was primarily due to the increase in the globulin concentrations which indicate with the marked increase observed in the urea concentration and marked increase or inhibition in the activity of either AST or ALT that the digestive gland of the 3 forms of snails is seriously affected by molluscicides. The 3 forms of B. glabrata showed low susceptibility to infection with the local strain of S. mansoni.

Animals↗
PubMed2003

Biomphalaria alexandrina: cellular responses of susceptible and resistant snails to Schistosoma mansoni infection.

Distribution pattern of Schistosoma mansoni miracidia level of host susceptility/resistance and the basic cellular responses brought into play during the parasite development. Several snail stocks showed a wide spectrum of host reaction to the parasite. From the present study, a vigorous "resistant-type" cellular response to invading miracidia is seen in the histological sections of non-susceptible snails. In this respect, they were classified in our study as "resistant snails". B. alexandrina experimentally infected with S. mansoni exhibit a wide range of histopathological and immunological changes. The rate of phagocytosis as well as the actual number of hemocytes were determined in different groups of snails during the infection cycle. The significant fluctuation (increase and/or decrease) in circulating hemocyte number was only correlated with a shift in hemocyte populations in the first two days after exposure to the infective stage. The in vitro phagocytic activity of resistant snail hemocytes was found to be higher than that observed in susceptible snails. The observed phagocytic activity indicates that susceptible snail hemocytes were capable of recognizing parasite antigen in vitro, despite of that, they were not able to clear the infection in vivo. Thus suggesting the presence of endogenous factors preventing the immune system of susceptible snails from destroying the developed parasite larvae. Therefore, the mechanism underlying the susceptibility of the snails should be investigated by studying the host-parasite interactions.

Animals↗
PubMed2003

A possible role for an enkephalinergic system in the internal defense mechanism of Biomphalaria alexandrina exposed to Schistosoma mansoni.

The present study documents that in Bioniphalaria alexandrina coordinated responses to Schistosoma mansoni infection are modulated by receptor-mediated opioid signals. Rather comprehensive tests in susceptible and resistant snails have demonstrated: I- the presence of an endogenaus opioids in the snail hemolymph (in particular, Leu-enkephalin-like material). II- in vitro treatment of snail hemocytes with synthetic Leu-enkephalin analogue (DADLE) resulted in the modulation of cellular adherence, and phagocytic activity. III- the addition of Naloxone, either alone or in combination whith DADLE, generally reduced hemocyte activity indicating opioid-receptor-mediated mechanism. V- the presence of DADLE or Naloxone modulated the level of IL-2-, TNF-gamma- and FNF-alpha-like molecules in S. mansoni resistant and susceptible snails. Specifically, DADLE and DADLE in combination with Naloxone generally were found to be capable of modulating resistant snail hemocytes at concentrations of 10(-6) and 10(-8) M. Similar actions after incubation with the same concentrations were not detected in the susceptible snails. These observations demonstrate the existence of a complete opioid system in B. alexandrina, associated with susceptibility and resistance to S. mansoni infection, the results suggest the role of such opioid system in molecular signaling within the host and in host-parasite interactions.

Animals↗
PubMedDate not supplied

Synthesis of pyrido[2,1-c][1,2,4]triazine,1,2,4 triazolo[4,3-a] pyridine and 2-(substituted-pyrazolyl)nicotinonitrile and their effect on Biomphalaria alexandrina snail enzymes.

The reaction of 2-hydrazino-4-(4-methoxyphenyl)-6-pheny-nicotinonitrile 3 with halo compounds yielded 4a-c,5,6. Heating 3 with carbon disulphide gave 7-(4-methoxyphenyl)-5-phenyl-3-thioxo-2,3-dihydro [1,2,4-] triazolo [4,3-a] pyridine-8-carboxylic amide 7. The behaviour of 3 towards some alpha,beta-unsaturated nitriles ,ethoxymethylene and ketene dithioacetal derivatives has been investigated, affording 9a-c,11a-c,13a-c,16a,b respectively. The activity of compounds 4a,5,6 and 7 have been investigated as molluscicidal.

Animals↗
PubMed2004

Influence of Capparis spinosa and Acacia arabica on certain biochemical haemolymph parameters of Biomphalaria alexandrina.

The work investigated the molluscicidal potency of dried Capparis spinosa and Acacia arabica leaves on selected biochemical parameters of Bionimphalaria alexandrina, in order to render them, physiologically, unsuitable for S. mansoni infection or at least disturb the life-cycle of the parasite within its respective snail host. The effect of the two plants on lactate dehydrogenase (LDH), 5'-nucleotidase, acid phosphatase (AP), aspartate and alanine aminotransferases (AST & ALT), alkaline phosphatase (ALP) and glucose content were studied. This work was extended to evaluate the effect of these two plants on protein profile as well as total protein (TP) content of snail's in haemolymph after 24 hours and one week of snails plants feeding. The study revealed that both plants induced marked alteration in all the measured parameters, where LC50 of C. spinosa after fed one week showed the most potent effect.

5'-Nucleotidase↗
PubMed2004

Compatibility of Biomphalaria alexandrina snails to infection with Schistosoma mansoni after exposure to sublethal concentrations of Myrrh.

The effect of exposing B. alexandrina to sub-lethal dose (LC10 & LC20) of Myrrh, on its susceptibility to infection with S. mansoni miracidia were determined. Starting three weeks post miracidial exposure, cercarial shedding was monitored. No shedding of cercariae were observed from snails treated with LC20. In snails treated with LC10, longer prepatent cercarial and shorter cercarial production periods than those of control group were recorded. The number of infected snails and of shedding cercariae were decreased. The study revealed that sublethal values of myrrh decreased the compatibility of B. alexandrina to S. mansoni infection thus playing an important role in the control of schistosomiasis.

Animals↗
PubMed2005

Semi field trials to control Biomphalaria alexandrina by different modes of exposure to certain plant and chemical molluscicides.

Semi-field trials were carried out in Snail Research Station under simulated natural conditions to evaluate different modes of exposure to Anagallis arvensis and Calendula micrantha as plant molluscicides and bayluscide and copper sulphate as chemical molluscicides. Firstly, B. alexandrina were exposed to the tested molluscicides alone and in addition to two densities of aquatic plants. No apparent effect of aquatic plants on the activity of both plant and chemical molluscicides, this may be due that the two densities of the aquatic plants used were insufficient to interfere with the molluscicides action. Secondly, snails were pre-exposed to three sub-lethal concentrations of the plant molluscicides for 24h then to three concentrations of the chemical molluscicides and vice versa. The results indicate that the pre-exposure increases the snail mortality significantly in all treatments of bayluscide and A. arvensis (except in the highest concentration when the snails firstly exposed to bayluscide then to A. arvensis, where the two compared treatment showed 100%) and in all treatments of bayluscide and C. micrantha. Also, in one treatment of copper sulphate and A. arvensis (in the highest concentration when the snails firstly exposed to A. arvensis then to copper sulphate) and in three treatments of copper sulphate and C. micrantha, (in least and moderate concentrations when snails firstly exposed to C. micrantha then to copper sulphate and in the highest concentration when snails firstly exposed to copper sulphate then to C. micrantha). Thirdly, snails were exposed to mixtures of six different ratios of bayluscide and each of A. arvensis and C. micrantha. The results indicated that the snail mortality increased significantly only in the first treatment of bayluscide and A. arvensis mixtures and in treatment number 6 of bayluscide and C. micrantha.

Animals↗