Myxobolus Cerebralis - Prevention and Control

Prevention and Control

Some biologists have attempted to disarm triactinomyxon spores by making them fire prematurely. In the laboratory, only extreme acidity or basicity, moderate to high concentrations of salts, or electrical current caused premature filament discharge; neurochemicals, cnidarian chemosensitizers, and trout mucus were ineffective, as were anesthetized or dead fish. If spores could be disarmed, they would be unable to infect fish, but it is unclear whether any of the methods that worked in the laboratory could be employed in the wild.

Some strains of fish are more resistant than others, even within species; using resistant strains may help reduce the incidence and severity of whirling disease in aquaculture. There is also some circumstantial evidence that fish populations can develop resistance to the disease over time. Additionally, aquaculturists may avoid M. cerebralis infections by not using earthen ponds for raising young fish; this keeps them away from possibly infected tubificids and makes it easier to eliminate spores and oligochaetes through filtration, chlorination, and ultraviolet bombardment. To minimise tubificid populations, techniques include periodic disinfection of the hatchery or aquaculture ponds, and the rearing of small trout indoors in pathogen-free water. Smooth-faced concrete or plastic-lined raceways that are kept clean and free of contaminated water keep aquaculture facilities free of the disease.

Lastly, some drugs, such as furazolidone, furoxone, benomyl, fumagillin, proguanil and clamoxyquine, have been shown to impede spore development, which reduces infection rates. For example, one study showed that feeding fumagillin to O. mykiss reduced the number of infected fish from between 73% and 100% to between 10% and 20%. Unfortunately, this treatment is considered unsuitable for wild trout populations, and no drug treatment has ever been shown to be effective in the studies required for United States Food and Drug Administration approval.

Recreational and sports fishers can help to prevent the spread of the parasite in a number of ways. Cleaning fishing equipment between fishing trips and never transporting fish from one body of water to another should protect against cross-contamination of waterways. Spores are particularly persistent in felt-soled wading shoes, which should be treated with 10% chlorine bleach and water for at least 15 minutes and then rinsed thoroughly. Fish bones or entrails should never be disposed of in any body of water, since spores from the carcass will be released into the waterway. Salmon and trout should not be used as bait.