To the best of our knowledge no other 

 group of parasites has representatives which 

 develop in cartilage or bone of the host, but 

 among the Myxosporidia there are 6 other 

 species which have been so recorded. They are: 

 Myxobolus aegelefini from the head skeleton of 

 Gadus , Pleuronectes, Molva , Merluccius (marine) 

 (Kabata, 1957); Myxobolus dentium from the base 

 of the teeth of Esox masquinongy (Fantham et al. 

 1939); Henneguya brachyura from the fin ray of 

 Notropis (Ward, 1919); Henneguya sp. in the 

 cartilage of gill of Pomoxis (Davis, 1923); and 

 Myxosoma sp. in the head cartilage of Lepomis 

 macrochirus (Hoffman, 1961, unpub. research). 

 To date the pathogenicity of cartilage parasites 

 has been studied only in M. cerebralis infections. 



During the past 3 years, we have studied 

 the symptoms, the cause, and have attempted to 

 infect fish experimentally to study methods of 

 control and treatment. Our results are here 

 incorporated in a review of the subject. 



HISTORICAL AND GEOGRAPHICAL 



The parasite and disease were first 

 described as Lentospora cerebralis by Hofer 

 (1903) in Germany. His associate, Marianne 

 Plehn (1904, 1924) described the disease, the 

 parasite, and the histopathology in greater 

 detail. SchSperclaus (1931, 1954) also described 

 the disease in detail and outlined a method of 

 control. Heuschman (1940, 1949), Tack (1951), 

 and Luling (1952) in Germany have also studied 

 whirling disease and its control. Vanco (1952) 

 records it from France, Kocylowski (1953) from 

 Poland, Scolari (1954) from Itally, Dyk (1954) 

 and Volf (1957) from Czechoslovakia, Uspenskaya 

 (1955, 1957) in trout and salmon from Russia, 

 SchSperclaus (1959, pers. comm.) from Denmark, 

 and Bogdanova (1960) in salmon from S.E. Russia. 

 Hoffman and Dunbar (1961) briefly reported on it 

 from the United States. 



The chronology of the reports indicates 

 that the disease originated in Central Eurpoe. 

 In support of this hypothesis is the fact that the 

 brown trout, a native of Europe, may become 

 infected but is resistant to the disease, whereas 

 the imported rainbow trout becomes seriously 

 diseased. 



OCCURRENCE IN THE UNITED STATES 



Whirling disease appeared in brook trout 

 at the Benner Spring Fish Research Station, 

 Bellefonte, Pennsylvania, in 1956; one pond of 

 fish was affected. European trout were circum- 

 stantially implicated in the appearance of whirl- 

 ing disease at Benner Spring; sample purchases 

 of frozen imported table fish may have been fed 

 accidentally, or their viscera discarded in 

 streams. The epizootic became severe in the 

 hatchery in 1957 and 1958 at which time a 

 tentative diagnosis was made by Dr. S. F . 

 Snieszko. This was verified histologically by 

 Dr . E . M . Wood, Fish Pathologist, Seattle, 

 Washington. In the spring of 1960 an attempt 

 was made to eradicate the parasite by using 

 calcium cyanamide (1/10 lb. per sq. ft.) in the 

 dirt ponds as recommended by Dr. Sch^perclaus 

 of Germany, and chlorine gas (max. 300 ppm) in 

 the spring water source and small reservoir. 

 A few trout were killed in the small reservoir, 

 but it was not certainly known if this was the 

 source of infection for the hatchery. There was 

 no recurrence of the disease in 1961 fingerlings 

 in the hatching building. We believe the disease 

 is under control and can be eliminated completely 

 in a year or so. Whirling disease did reappear 

 later in some of the dirt ponds, however. As 

 long as the spring water supply remains unin- 

 fested there probably will be no recurrence of 

 the disease in the hatching building. We hope 

 the spores presumably remaining in and around 

 the ponds will eventually be eliminated. 



The National Fish Hatchery, Lamar, Pa., 

 is on the same watershed as Benner Spring and 

 in 1960 Mr. Fred Howard discovered the disease 

 there. The disease was verified by the Eastern 

 Fish Disease Laboratory. There were only a 

 few fish affected, and we believe that only one 

 series of ponds was contaminated. The Lamar 

 Hatchery plans to treat the ponds, when drained, 

 with calcium cyanamide. All diseased fish were 

 incinerated. 



In December 1961, Mr. Lyle Pettijohn 

 diagnosed Myxosoma cerebralis disease in 

 fingerling rainbow trout from the Kensington 

 State Fish Hatchery, Kensington, Connecticut. 

 The hatchery personnel had noticed symptoms. 



