Location of Bulinus (Physopsis) globosus by Miracidia of Schistosoma haematobium

Young Bulinus (Physopsis) globosus snails were exposed to miracidia of Schistosoma haematobium under various conditions of mutual dispersion to investigate host location mechanisms. There is little variation in infectivity of miracidia taken from different human hosts on different days. Exposure of...

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Bibliographic Details
Published in:The Journal of parasitology 1968-12, Vol.54 (6), p.1133-1140
Main Author: Shiff, C. J.
Format: Article
Language:English
Subjects:
Animals
Chemotaxis
Ecology
Flow velocity
Humans
Infections
Larva - growth & development
Lice
Mazes
Miracidia
Mucus
Parasite hosts
Parasitism
Schistosoma - growth & development
Schistosoma - physiology
Snails
Turbulence
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Summary:Young Bulinus (Physopsis) globosus snails were exposed to miracidia of Schistosoma haematobium under various conditions of mutual dispersion to investigate host location mechanisms. There is little variation in infectivity of miracidia taken from different human hosts on different days. Exposure of one snail to one miracidium in cylindrical vessels with diameters ranging from 2.3 to 29.0 cm filled to 0.5 cm depth resulted in infection of about 42% of snails; this percentage did not increase if three snails were used in each exposure. With the snails confined under small perspex cages, the percentage infected by single miracidia rose significantly. It is suggested that this was the result of a chemotaxis, and experiments using a simple Y-maze demonstrated an initial response some distance from the snail. In a long trough miracidia were found to range over 294 cm in still water; in water flowing at 15 cm/sec 10 miracidia per snail produced no infections. At 7.5 cm/sec 6.7% of snails became infected. The introduction of a weir to cause turbulence increased infection. It is suggested that miracidia of S. haematobium are unable to infect snails in moderately fast-flowing water unless turbulence occurs near the snails.
ISSN:0022-3395
1937-2345
DOI:10.2307/3276977