including man, such as rabies, equine encephalomyelitis, swine 
influenza, 2 fever, and vesicular stomatitis. 
A few virus diseases, such as hog cholera and horse sleeping 
sickness, frequently cause a very high death rate. Others, ine 
eluding infectious anemia of horses, vesicular exanthema of 
swine, ecthyma and scrapie of sheep, and the pox viruses, cause 
little mortality but affect production and usefulness of the 
animals, Still others, such as virus abortion of horses, may 
affect only the reproductive system. 
The diagnosis, control, prevention, treatment, and eradication 
of these virus diseases depend on the scientific information 
available about them. The more that is known about a virus and 
its characteristics, the more successful will be the application 
of sound control measures. Sometimes a weak link in the life 
cycle can be broken to make control relatively easy; at other 
times nature has provided a much more complex and effective 
system for propagating the disease. 
In addition to the high average annual loss from the virus di- 
seases of livestock, large sums of money for antibiotics, sulfa 
drugs, other pharmaceuticals, disinfectants, biologics, etc., 
are paid to veterinarians, drug stores, feed stores, mail-order 
houses, and other distributors from whom there is no available 
means of obtaining reliable estimates. 
For some of these diseases loss estimates could not be included 
in the tables, since information about incidence, mortality, and 
morbidity is not available. These diseases include infectious 
anemia and virus abortion of horses; Q fever, infectious dysentery, 
cow pox, and warts of cattle; scrapie and ecthyma of sheep; virus 
enteritis, swine pox, and influenza of swine, There are frequent 
field reports from livestock owners, veterinary colleges, experi- 
ment stations, and livestock sanitary officials, as well as in 
research publications, describing diseases highly suggestive of 
virus origin. 
Because these diseases are difficult to recognize, their economic 
importance cannot be evaluated without an organized cooperative 
effort on the part of farmers, veterinarians, county agents, drug 
merchants, chemical, pharmaceutical, and biological companies, 
diagnostic laboratories, and State and Federal agricultural diseasee 
control officials. 
Recterial and Myeotic Diseases of Livestock 
Diseases caused by bacteria bring heavy losses to the livestock 
industry. Many of these diseases are enzootic in the United 
States, and only a few are being controlled by national programs, 
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