TRANSMISSIBLE FOWL LEUKOSIS 3 



HISTORICAL ASPECTS 



The disease of fowl leukosis was first described in 1896 by Caparini (23) in 

 Italy. It is of interest that leukemia in man was described in 1845 (Craigie 25, 

 Bennett 12, and Virchow 208) and had also been previously described in other 

 lower animals: horse in 1858 (127), swine in 1865 (127), cat in 1871 (180), dog in 

 1874 (17, 18), and bovine species in 1876 (180). Warthin (215), Koch and Rabin- 

 owitsch (122), and Kon (123) made observations on the spontaneous occurrence 

 of fowl leukosis in 1907. Butterfield (22) in 1905 described three livers of hens 

 on which he made the diagnosis of "aleukemic lymphadenosis." These probably 

 were not examples of the disease now recognized as transmissible fowl leukosis, 

 as there was no indication of a leukemic state. However, in this report. Butter- 

 field mentions a communication from Dr. J. R. Mohler of the Bureau of Animal 

 Industry, United States Department of Agriculture, describing five cases in each 

 of which there was evidence of a leukemic state in conjunction with infiltration 

 of the visceral organs. These cases might possibly represent instances of fowl 

 leukosis. 



A significant advance was made by Ellermann and Bang (45) who in 1908 re- 

 ported the successful transmission of the disease with a filtrable agent. Hirschfeld 

 (93) and Hirschfeld and Jacoby (94), working with leukosis agent derived from 

 the original strain of Ellermann and Bang, confirmed the findings as to transmis- 

 sion and ruled out tuberculosis as the cause of the disease, an idea advanced by 

 Burckhardt (19). In 1915 Schmeisser (177) reported the development of another 

 transmissible strain of fowl leukosis and in the same year Magnusson (133) re- 

 ported transmission of the disease. Since this time a number of different trans- 

 missible strains of the disease have been described by investigators in various 

 parts of the world, as indicated in the appended synopsis. 



The occurrence of the disease has been reported in Denmark (45), Germany 

 (130), England (11), Sweden (133), Italy (6), Hungary (97), Russia (218), Holland 

 (197), Japan (139), United .States (215), France (151), South Africa (95), Brazil 

 (168), and New Zealand (65). 



TYPES OF TRANSMISSIBLE FOWL LEUKOSIS 



Ellermann (38, 39, 43, 44) distinguished three general types of leukosis; namely, 

 myeloid leukosis (leukemic and aleukemic), intravascular lymphoid leukosis 

 (also known as erythroleukosis) and lymphatic leukosis (an extravascular process). 

 Later investigators have, in general, followed the classification which he propound- 

 ed, although certain exceptions to the relationship between these various forms 

 have been made. 



Erythroblastic Leukosis 



Synonyms for this form of leukosis are: erythroleukosis (Ellermann 44, Furth 

 72), intravasculare lymphoid leukose (Ellermann 39), leucose a cellules sanguines 

 primitives (Andersen and Bang 2), erythroblastosis (Engelbreth-Holm and 

 Rothe Meyer 55), mielosi eritremica (Battaglia and Leinati 6) leukomyelose 

 (Kitt 121), leucemie erythroblastique (Oberling and Guerin 146), erythromyelosis 

 (Bayon 7), and mielosi eritremica normoblastica transmissible (Storti and De 

 Filippi 184). 



Two types of erythroblastic leukosis are recognized by many investigators 

 among whom are Jarmai (99), Furth (72), Stubbs and Furth (194), Bedson and 

 Knight (11), Engelbreth-Holm and Rothe Meyer (55), and Oberling and Guerin 



