Method fighting tsetse infections used against salmon parasites
Canada: Patrick Woo, a University of Guelph parasitology professor, developed a new method for fighting deadly parasites in farmed and wild salmon. The basis for his research with salmon was the work he did the 1970s when he discovered a quick and easy way to diagnose sleeping sickness caused by a parasite infecting people in West Africa spread by the tsetse fly.
Dr. Woo took interest in parasite problems, Salmonid Crptobiosis and Salmonid Spironucleosis, found in farmed and wild salmon in British Columbia which is killing large number of fish.
A team of U of G researchers led by Dr. Woo developed a method to inoculate fish against the parasites without having to stick each fish with a needle. They found a way to use leeches to deliver a non-deadly bite to the fish. The bite transferred protection against the parasite.
Thus far the industry has not adopted Dr. Woo's method but it has the potential to protect millions of farmed fish.
Salmonid Cryptobiosis is caused by the hemoflagellate, Cryptobia (T.) salmositica, and the parasite is normally transmitted by leeches (Piscicola salmositica) in streams and rivers, but direct transmission can also occur when infected and uninfected fish are held for prolonged periods in the same tank or under certain hatchery conditions. The disease is characterized by anorexia, exophthalmia, splenomegaly, hepatomegaly, general edema and abdominal distention with ascites, a microcytic and hypochromic anemia, and red cells give a positive antiglobulin reaction. Infected fish are highly susceptible to environmental hypoxia, and their metabolism and swimming performance are reduced.
Salmonid Spironucleosis is caused by Spironucleus - the parasite is in the blood and internal organs of fish. It is morphologically similar to the intestinal flagellate (Hexamita) in fish, and both parasites are closely related to the Giardia in mammals. The parasite causes morbidity and mortality in fishes and there have been outbreaks of the disease in salmon cultured in sea cages - in Chinook salmon on the west coast of Canada and in Atlantic salmon in Norway.
