Veterinary/zoology session

Snails are important from a veterinary point of view because they serve as intermediate hosts of different parasites. They are vectors of many helmintoses of farm animals, for example different species of protostrongylid nematodes, or Dicrocoelium, Fasciola, Paramphistomum flukes and some cestodes of poultry. The larvae of worms that develop in snails are usually being investigated on laboratory reared snails. This well known process has been very effective for example in examinations of feared human parasitosis like shistosomosis for a long time. Intermediate hosts of blood flukes are freshwater snails, which can be reared easily in aquarium. However, parasites developing in land snails are difficult to study under artificial circumstances, because it is more troublesome to maintain those snails in closed area, than aquatic species.

Snails collected from nature cannot be used for experimental infections, since we do not know whether they carry parasites or not. In addition, snail specimens taken from their natural environment usually die quickly among artificial circumstances. Therefore, parasite-free colonies of land snails should be established for experiments, that can be maintained in laboratory. We intended to produce specific parasite-free (SPF), self-maintaining colonies of terrestrial snail species, that are susceptible to many kinds of parasites, and can be reared in small places. Our choice fell to the terrestrial Stylommatophoran snails because all of them are adequate intermediate hosts of various protostrongylid, angyostrongilid worms, Dicrocoelium trematodes, and they are rather common in Hungary.

We reared several small-sized snail species in self-designed, transparent, plastic boxes, under determined circumstances of light and humidity. These snails were partly grass-dwelling species that may easily transmit parasites to farm animals and others were greenhouse dwellers being adopted to exist in restricted habitats. Laboratory breeding was successful in case of Vallonia costata, V. pulchella and Cochlicopa lubrica (belonging to the first group) and Lamellaxis clavulinus from the second group. These species produced more fully-developed offspring than the parents during one year, thus a self-maintained, parasite-free (SPF) colony was established. The reared progenies of these species were infected experimentally with protostrongylid larvae, and their susceptibility to parasitic nematodes was confirmed.