PRACTICES TO PREVENT THESPREAD OF WHIRLING DISEASE

Do (If local trout are infected with whirling disease)

Remove all mud and aquatic plants from your ve-hicle, truck, tractor, boat, ATV, four wheeler, anchor,trailer, axles, waders, boots, shoes, and fishing gearbefore departing from the fishing location.

Drain all water from and dry your boat and equip-ment before entering another fishing location.

Disinfect gear and equipment with 10 per centchlorine bleach to kill the WD spores.

Dispose of inedible, uncooked fish parts by totalburning, by burying away from the fishing location,or by placing in the garbage.

Wash down livestock in contaminated areas be-fore moving them to a new location.

Don’t (If local trout are infected with whirling disease)

Transport live or dead fish from one body of waterto another. Don’t use dead or live contaminatedfish as bait.

Dispose of fish entrails down the disposal, asspores are not destroyed at sewage treatmentplants.

Dispose of fish entrails, skeletal parts or other by-products in any body of water.

Leave fish entrails where wild animals or birdsmay access them.

Travel from a contaminated area to an uncon-taminated area without first throughly washingall mud off of your agricultural or recreationalvehicle.

AnAgriculturalPerspective

Utah Department of Agriculture and FoodDivision of Animal Industry

Fish Health Program

WhirlingDisease

andAquaculture

Action Taken By The Department OfAgriculture And Food To PreventThe Spread Of Whirling Disease

The Utah Department of Agriculture and Food gov-erns fish species that are imported into the state and pos-sessed or transported within the state that are applicableto commercial aquaculture or fee fishing facilities. It is theresponsibility of the department to prevent the outbreakof whirling disease (WD) and to control the spread of thedisease among trout in commercial aquaculture and feefishing facilities. An entry permit is required for trout spe-cies imported into Utah, and all sources of trout must testnegative for WD prior to entry. Trout in all aquaculturefacilities undergo testing for WD at least once a year.Trout must test negative before they may be transportedfrom one facility to another. If the disease is confirmed atan aquaculture site, then the trout are either quarantinedor destroyed. The department either regulates the destruc-tion of fish at the facility or the remediation of the site ifpossible. All commercialaquaculture facilities that sell live trout in Utah must havetheir fish tested negative for WD during the past 12 monthsprior to the sale. Sales of dead trout are also regulated.Time is also spent educating operators of aquaculturefacilities on how to prevent the spread of whirling dis-ease. Trout importation and sales are controlled in Utah toprevent the spread of WD. Fish imported into Utah aresubject to inspection at ports of entry or during transport.Fish haulers are required to carry documentation uponentry into Utah and may be required to stop at ports ofentry. Documentation must verify that trout are WD free. Ifproblems arise, fish health specialists from the Depart-ment of Agriculture may be contacted. Anyone who ille-gally transports and sells fish in Utah is subject to finesand legal action. Fish operators who haul trout throughUtah are only allowed to remain in the state up to 72 hoursand may be subjected to inspection by local authorities.

For more information contact the fishpathologist or fish health specialist atthe Utah Department of Agricultureand Food (801) 538-7029.agmain.khauck@state.ut.usagmain.mmartin@state.ut.us

Courtesy of Angler’s Inn

This brochure is endorsed bythe Utah Fish Health Policy Board.

Whirling disease has been in the Eastern United Statessince 1956 and was first discovered in Utah in 1991. Thedisease was probably present in Utah up to five years priorto its discovery. Whirling disease is presently found in allof the Western United States. Rainbow trout appear to bethe most susceptible of all the trout family. Studies havesuggested that the parasite originated in Europe in browntrout. Over the years the brown trout has possibly devel-oped immunity to the parasite. Young trout are most sus-ceptible to WD. When an infected fish dies, hundreds to thousands ofthe spores are released into the water. These spores areextremely durable; they can withstand extremes in heat,cold, and dehydration and can survive in dried mud up toone year and in a stream or lake 20 to 30 years. A tinyaquatic worm known as Tubifex tubifex may eventuallyingest them. When the tubifex worms release the parasite,they become an infective TAM that may infect a trout.

Whirling disease (WD) is an infection of trout andsalmon caused by a microscopic parasite known asMyxobolus cerebralis. When present in the water theminute parasite attacks the cartilage of the head andspine of salmonids. In severely infected fish it cancause skeletal deformities (especially of the head),darkening of the tail, and a distinctive rapid whirlingor swimming in circles. Whirling disease particularlyaffects young trout and can lead to death in cases whenmany parasites are present. In descending order, thosetrout in Utah most susceptible to whirling disease in-clude rainbow, golden, cutthroat, brook, brown andsplake. Trout can reproduce without passing the para-site to their offspring. There is currently no knowncure for fish infected with the parasite. Whirling dis-ease can be controlled in hatchery environments, butcurrently cannot be controlled in wild fish environ-ments. Trout infected with WD will not harm humansand are suitable to eat.

Shipping and stocking of unapproved pond fishor fish from any unapproved source.

Sportsmen or fishermen may spread the pathogento agricultural ponds from mud or debris on bootsand gear.

Flood irrigation or sprinkling roadways with ir-rigation water that is contaminated with whirlingdisease spores. In this manner vehicles travelingthe roads may pick up the spores and transportthem to another location when contaminated mat-ter falls from vehicles.

Grazing livestock in contaminated pastures and thenrelocating them to another vicinity may spread thedisease. Spores in the mud or water may attach toanimals and dislodge at another site.

Livestock and wildlife that frequent contaminatedrivers and streams may travel to other areas andspread the disease from mud attached to their legsand bodies. Wild fish in water that supplies apond on a farm may be contaminated.

Tractors, farm equipment, four wheelers, and ve-hicles that travel though contaminated areas maycarry contaminated mud and spread the diseaseby traveling to uninfected areas. Mud from thesevehicles may contain whirling disease spores thatdislodge at another location. Those responsiblemay include ranchers, farmers and sportsmen.They may spread the disease over large distances.

HOW CAN WHIRLING DISEASE BESPREAD IN AGRICULTURAL AREAS ?

Salmonid whirling disease spores

WHIRLING DISEASE IN UTAH

WHAT IS WHIRLING DISEASE ?

7. The parasites “feed” oncartilage. Infected fish mayexhibit a “whirling” behavior,spinal and head deformities.

1. Whirling disease isan infection caused by amicroscopic parasitespore (Myxoboluscerebralis). Thesespores are normallyreleased into water andsediment after thedeath of an infectedfish.

2. Bottom-dwelling tubifexworms eat the spores.

3. Inside the tubifexworm, the spore changesform and becomes aTriactinomyxon (TAM).

4. TAMs are released fromthe tubifex worm into thewater.

5. Healthy trout are infectedwhen the tiny TAMs cling tothe fishes body or when theyingest infected tubifexworms. The TAMs thenenter the trout’s nervoussystem.

6. Inside the fish, the TAM changes formagain and moves into cartilage nearthe head. The young fish may exhibitblack tails.

8. When the infected fish dies or is eatenby a predator, the mature spores in itsbody are released into the water andsediment. The cycle starts over again afterspores are ingested by tubifex worms.

Illustration by Linda Martin