Cryptobia spp and Trypanosoma spp are slender, elongated (6-20 µm), actively motile, biflagellated protozoan parasite that are easily detected in fresh blood and tissue smears of both marine and freshwater finfish. Hematogenous forms are generally described as Trypanosoma and have a well-developed undulating membrane.
Trypanosomes may be transmitted by leeches and have been associated with anemia in blue-eyed plecostomus imported from South America. Cryptobia iubilans has been associated with granulomatous disease in African cichlids and discus.
Clinical disease is manifest by severe weight loss and cachexia. Clinically affected fish should be culled. Presumptive diagnosis can be made from microscopic examination of fresh tissue. Typically, granulomas will be found in the stomach, which may be visibly thickened. Acid-fast material will not be found in granulomas caused by Cryptobia. Motile flagellates may be visible using magnification of 400¥ or greater. Transmission electron micrographs are required to confirm the diagnosis of C iubilans.
Infected fish may respond to metrobidazole and vaccines are currently being devloped for this disease.
- Merck Veterinary Manual
- Guo, F.C. & Woo, P.T.K. (2009) Selected parasitosis in cultured and wild fish. Vet Parasitol 163:207-216
- Tan, C.W., Jesudhasan, R.R.R. & Woo, P.T.K. (2008) Towards a metalloprotease-DNA vaccine against piscine cryptobiosis caused by Cryptobia salmositica. Parasitol Res 102:265-275