Many crustaceans like crabs (Scylla spp., Portunus spp.), spiny lobsters (Panulirus spp.), crayfish (Astacus spp., Cherax spp.) and freshwater shrimp (Macrobrachium spp.) are reported to be infected with variable severities depending on the life stage of the host and presence of external stressors (temperature, salinity, bacterial diseases, pollutants).