Human schistosomiasis is a common parasitic disease endemic in many tropical and subtropical
countries. One barrier to achieving long-term control of this disease has been re-infection
of treated patients when they swim, bathe, or wade in surface fresh water infested
with snails that harbor and release larval parasites. Because some snail species are
obligate intermediate hosts of schistosome parasites, removing snails may reduce parasitic
larvae in the water, reducing re-infection risk. Here, we evaluate the potential for
snail control by predatory freshwater prawns, Macrobrachium rosenbergii and M. vollenhovenii,
native to Asia and Africa, respectively. Both prawn species are high value, protein-rich
human food commodities, suggesting their cultivation may be beneficial in resource-poor
settings where few other disease control options exist. In a series of predation trials
in laboratory aquaria, we found both species to be voracious predators of schistosome-susceptible
snails, hatchlings, and eggs, even in the presence of alternative food, with sustained
average consumption rates of 12% of their body weight per day. Prawns showed a weak
preference for Bulinus truncatus over Biomphalaria glabrata snails. Consumption rates
were highly predictable based on the ratio of prawn: snail body mass, suggesting satiation-limited
predation. Even the smallest prawns tested (0.5-2g) caused snail recruitment failure,
despite high snail fecundity. With the World Health Organization turning attention
toward schistosomiasis elimination, native prawn cultivation may be a viable snail
control strategy that offers a win-win for public health and economic development.
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