TRANSMISSIBLE FOWL LEUKOSIS. A REVIEW OF THE 

 LITERATUREi 



By Carl Olson, Jr. 

 Research Professor of Veterinary Science 



CONTENTS 



Page Page 



Introduction 2 Experimental 12 



Historical aspects 3 Types of disease produced 13 



Types of transmissible fowl leukosis 3 Incubation period and course 17 



Erythroblastic leukosis 3 Pathogenesis 19 



Granuloblastic leukosis 4 The transmissible agent 22 



Types of disease sometimes classified as Filtrability 22 



"Fowl Leukoses" 4 Biological properties 23 



Lymphocytoma 4 Specificity 27 



Myelocytoma 7 Immunity 29 



Fowl paralysis 7 Treatment 33 



Incidence of fowl leukosis 9 Attempts to produce leukosis without the 



Transmission of fowl leukosis 10 use of the specific agent . 33 



Relation of ectoparasites 11 Conclusions 36 



Through the egg 11 References 36 



INTRODUCTION 



A group of diseases sometimes referred to as "fowl leukoses" has become of 

 much interest in the past few years to those concerned with diseases of the domes- 

 tic chicken. These diseases represent a serious menace to the poultry industry 

 because of the large losses which are caused by them. The actual loss that may 

 be attributed to this group of diseases is very difficult if not impossible to evaluate 

 with any degree of precision. It may be said, however, that the losses due to 

 these diseases are greater than those from any other disease for which we as yet 

 have no adequate means of control. 



There is considerable uncertainty as to the relationship between the various 

 disease processes which have been described in the literature under the term 

 "fowl leukoses." This uncertainty is due in part to the varying results that have 

 been obtained in the experiments of different investigators and also to indiscrim- 

 inate use of terms applied to the disease processes. Such a state of confusion is 

 not conducive to clear understanding of the fundamentals of these diseases. 

 It would seem, therefore, that a review of the literature on transmissible fowl 

 leukosis would be of considerable value to those who are interested in the problem 

 but who have neither the time nor the facilities to engage in an exhaustive study 

 of the literature. It is with this purpose in mind that this discussion is presented. 



Although the disease process referred to as "transmissible fowl leukosis" con- 

 stitutes the main subject of this review, it is necessary to elaborate upon the other 

 diseases sometimes classified with it in the group of so-called "fowl leukoses." 

 It is preferable to use the term leukosis or transmissible fowl leukosis in the re- 

 strictive sense to indicate a single entity in which there is a characteristic dis- 

 turbance of the myeloid tissue. The term will be used in this sense throughout 

 this review except where quotation marks indicate the use of the term in the 

 sense implied by the particular author cited. 



^This article is a revision of a portion of a thesis submitted to the Graduate School of the Univer- 

 sity of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy, 

 while associated with the Mayo Foundation, Rochester, Minn. 



