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Hadasit study on fluorescent treatment for Saprolegnia parasitica

by the Fish Site Editor
25 September 2007, at 1:00am

ISRAEL - Hadasit is involved in an advanced study of specific types of fluorescent whitening agents as a treatment for Saprolegnia parasitica, one of the most prevalent fish pathogens.

The whitening agents are being studied for both prevention and treatment applications of this damaging infections which occur in aquatic organisms including fish and fish eggs.

The study, funded by the Chief Scientist of the Ministry of Agriculture of Israel, is being conducted at the Hadassah-Hebrew University Medical Center, Jerusalem and the Laboratory of Fish Health in Nir David. It is expected to last for two years and the data collected will be presented to the Veterinary Chemical Products Registration Committee, Israel’s regulatory body for chemical permits.

"The immune systems of fish decrease when in stress conditions, such as a cold environment. Deadly zoospore, the infective unit of the water mold, which thrives in cold water, capitalises on the fragile condition of the fish by latching on and spreading its hyphae on the fish skin," said Professor Itzhack Polacheck, head of the Medical Mycology Laboratory in the Department of Clinical Microbiology and Infectious Diseases, at the University.

The infection results in white patches of filamentous mycelium on the body and fins of the fish, a condition that used to be treated with Malachite Green. However, this agent has been prohibited due to its carcinogenic properties, so alternatives are rapidly being researched.

"We've identified an alternative treatment that is non-carcinogenic, non-toxic and very economical," said Professor Polacheck.

Huge financial loss
The economic loss assocaited with Saprolegnia parasitica infection is in the tens of millions of dollars for many countries worldwide. In the US alone, "winter kill" in Catfish caused by Saprolegnia, costs the industry an annual $40 million loss. In Japan, there is an annual mortality rate of 50 per cent in Coho Salmon and Elver due to this water mold. Aquaculture businesses in Scotland, Scandinavia, Chile, Canada and Israel, suffer similar "winter kills" on their respective local fish populations.

"Diaminostilbene derivatives, used as fluorescent whitening agents, are highly water-soluble, safe to living organisms and the environment, therapeutically effective, and economical. In fact, they are part of a large group of substances that are already widely used in commercial products in the textile industry. Our research group has discovered a new application of these compounds," said Dr. Rama Falk, of Hadassah a member of the study team. Others involved in with the research include Fish Veterinarian Dr. Simon Tinman and Mr. Nir Froyman, the head of the Laboratory of Fish Health, both from the Central Fish Health Laboratory of the Ministry of Agriculture of Israel.

Although there is a vast amount of information already availbable on this group of compounds the Hadasit study will focus on toxicology and residues assocaited with this kind of of treatment in fish. The study will also analyse the mechanism of antifungal activity of this compound - primarily how it works to control and prevent infection.

Hadasit is actively seeking potential partners interested in supporting and co-ordinating the regulatory, manufacturing and marketing aspects of this project.

Further Reading

- Find out more information on FUNGAL DISEASE by clicking here.

the Fish Site Editor