Gastropods and their participation in transmission of Trichinella spp. in water biocenosis

Trichinellosis is a dangerous zoonotic disease caused with nematode Trichinella
spp. Trichinella have a strongly pronounced polyhostality. The spectrum of
their hosts covers more than 150 species of animals including sea mammals. Taking
into account the habitat of sea mammals, unlike land mammals, it is hard to
imagine the process of infection with Trichinella; nevertheless some domestic and
foreign authors point at infection of sea mammals with this species of helminths.
Up to the present moment the mechanism of transmission of infectious agent to sea
mammals using fish for food, different types of zooplankton and zoobenthos are
not explored. Mollusks are one of the important food objects for walruses and hairseals.
Mollusks (up to 20 species) are used as main food for pacific walrus Odobenus
rosmarus divergens in all its habitats, as for bearded seal Erignathus barbatus
– mollusks take the second place, for rough seal Phoca hispida and spotted seal
P. largha this type of food is used in a less degree. For the purpose of determination
of role of mollusks by transmission of trichinellas to obligate hosts – inhabitants
of water biocenosis, we carried out a set of experiments using a widespread
great pond snail (Lymnaea stagnalis). It is determined that gastropods are able to
swallow up not only decapsulated larvae of Trichinella but also encapsulated larvae.
Larvae of Trichinella is alive and has infective properties after passing through
gastrointestinal tract of gastropods for the time period from 24 up to 48 hours.
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Keywords: trichinellosis, great pond snail, mechanical carrier, sea mammals.