Growth conditions until patency

Introduction
The length of the prepatent phase of S. mansoni in B. glabrata is highly dependent on maintenance temperature. If the snails are maintained continually at 26ºC, some snails can begin to liberate (shed) cercariae by 28-30 days after they are exposed to miracidia. In this four-week window, it is critical to get your 3-5mm snails as large as possible so that they can maintain themselves and their parasites as long as possible. It’s best to split your snails into multiple containers, this ensures less competition for food and total loss if the water fouls from overfeeding.

Equipment
Incubator or modified room that can hold a steady temperature, ~ 26ºC

Materials and reagents
Suitable pans for maintaining snails (examples; hydroponic pans, food storage containers)
Lettuces e.g. romaine (never use a tender lettuce like butter lettuce), algae, gel snail food

Procedure

• Maintain snails in shallow containers at a density of 12 – 15 snails per 1.5 L
• For a food source, use fresh lettuce, algae, gel snail food or a combination
• Be careful not to overfeed, give the snails enough food that can be cleared in 2 days
• Change the aquarium water regularly, especially if water becomes cloudy, snails are clinging to the perimeter at the water’s edge or a foul odor is detected Recommendations
• The greatest amount of cercarial shedding typically occurs 1-2 weeks after initial shedding, but absolute numbers of cercariae vary between snails and are dependent upon many factors.

References
Standen, O. D. 1952. Experimental infection of Australorbis glabratus with Schistosoma mansoni. I. Individual and mass infection of snails, and the relationship of infection to temperature and season. Annals of Tropical Medicine and Parasitology 46: 48-53.

Stirewalt, M. A. 1954. Effect of snail maintenance temperatures on development of Schistosoma mansoni. Experimental Parasitology 3: 504-516.

Lewis, F.A., Stirewalt, M.A., Souza, C.P., and Gazzinelli, G. 1986. Large-scale laboratory maintenance of Schistosoma mansoni, with observations on three schistosome/snail host combinations. Journal of Parasitology 72, 813-829
Tucker, M. S., Karunaratne, L. B., Lewis, F. A., Frietas, T. C., and Liang, Y-S. 2013. Schistosomiasis, in Current Protocols in Immunology 19.1.1-19.1.57, John Wiley and Sons, Inc. Nov 2013 in Wiley Online Library (wileyonlinelibrary.com). doi: 10.1002/0471142735.im1901s103.