dead-end hosts. The virus is most commonly 

 transmitted from bird to bird, with mosquitoes 

 the principal vector. 



Sometimes horses are infected without the 

 involvement of man. When both horse and 

 man are involved, horse cases generally pre- 

 cede the human by 2 weeks. What factors are 

 responsible for this periodic "spill-over" from 

 birds into horses and man is not known. 



With our present knowledge that the virus 

 affects the horse, mule, ass, deer, pheasant, 

 wild birds, and humans, it seems more appro- 

 priate to designate the disease viral encepha- 

 litis. 



In horses, following incubation of several 

 days to 3 weeks, the disease produces typical 

 symptoms of an encephalitis, including fever 

 of 107° F., rapid paralysis, sleepiness, eventual 

 respiratory failure, and death. With the more 

 virulent eastern type there may be 90 percent 

 fatality. Horses can be protected by preseason 

 inoculation with a bivalent vaccine, and mos- 

 quito control. 



In pheasants, symptoms resemble the paraly- 

 sis of botulinus intoxication. Outbreaks among 

 pheasants in the Northeast generally accom- 

 pany those in horses — suggesting involvement 

 of the same vector. Mortality can exceed 60 

 percent. 



Present knowledge of viral encephalitis re- 

 moves the stigma from the horse as a danger 

 to public health. 



The Division has no eradication program for 

 viral encephalitis, nor is one contemplated. 

 Nevertheless, in these times of alertness to the 

 threat of biological warfare, a prompt diag- 

 nosis is essential — not only for recognition of 

 viral encephalitis, but also to be sure that it 

 is not .something else, more deadly and more 

 difficult to control. 



POULTRY DISEASES 



Poultry progress 



Throughout the pages of history, man has 

 waged constant war against disease. Next to 

 those directly affecting him and his family, 

 the diseases that threatened his food supply 

 have been of greatest importance. As the re- 

 sult of improved husbandry practices and eco- 

 nomic pressures on the producers, the place of 



poultry in this food supply has increased many- 

 fold since the days of chicken for "Sunday din- 

 ner." The housewife now has a choice between 

 poultry or red meat products never before 

 achieved in food logistics. 



Conscious of the ever-present possibilities 

 of economic disaster and loss of this vital seg- 

 ment of the Nation's food supply due to disease, 

 the U.S. Department of Agriculture, at the in- 

 dustry's reque.st, establi.shed a Poultry Disease 

 Section July 9, 1956. Its purpose was to coor- 

 dinate national poultry disease control and 

 eradication. The section cooperates closely 

 with State Livestock Sanitary officials, research 

 workers, the poultry industry, and other inter- 

 ested governmental agencies. 



To provide its veterinarians witli additional 

 experience in poultry disease work, the Divi- 

 sion, in 1956, started a training program at 

 Iowa State University. Poultry disease diag- 

 nostic courses conducted in 1957, 1958, and 

 1959 made available for immediate field work 

 49 Federal, 12 State, and 2 veterinary prac- 

 titioner poultry diagnosticians. Graduates 

 have at their disposal a poultry diagnostician's 

 kit of equipment plus detailed instructions in 

 ADE Division Memorandum No. 501.4, Supple- 

 ment 2, entitled "Investigation of Suspected 

 Emergency Poultry Disease Outbreaks." 



Ornithosis outbreaks 



The immediate problem facing the new Poul- 

 try Disease Section was the alarming increase 

 in the number of cases of ornithosis in turkey 

 flocks in Oregon and Texas. Ornithosis in 

 poultry and other species, or "psittacosis" as 

 the disease is known in the parrot bird family 

 and man, was first described in 1874 in Euro- 

 pean literature. 



Evidence obtained since 1950 has indicated 

 that ornithosis is fairly widespread among 

 domestic turkeys. It has also been diagnosed 

 in ducks and chickens. Numerous epidemics 

 in humans have been traced to exposure of 

 processing plant employees to diseased poultry 

 or to recent importations of infected parrots 

 or psittacine birds. Human cases of psittacosis 

 have been most severe in Oregon and Texas; 

 death has resulted in several instances. 



A regulation to control ornithosis or psit- 

 tacosis was published in the Federal Register 



34 



