102 



MISCELLANEOUS PUBLICATION NO. 1065, U.S. DEPARTMENT OF AGRICULTURE 



the world in 1849 that epidemics of cholera de- 

 rived from fecal pollution of drinking water. 

 From 1857 onward, William Budd investigated 

 the nature and mode of spreading typhoid fever. 

 Over the past century, civilized people have de- 

 veloped a well-founded awe for the grave conse- 

 quences that may arise from water and soil con- 

 taminated with infectious organisms. 



The potato famine of 1846 in Ireland demon- 

 strated with widespread human suffering that a 

 famine caused by an airborne plant disease can be 

 just as ravaging as an outbreak of typhoid fever. 

 Animal Disease Agents 



As our population expands, all phases of our 

 livestock industry — including production, trans- 

 portation, slaughter, and processing — may be ex- 

 pected to increase in magnitude, with these opera- 

 tions becoming more concentrated geographically. 

 Consequently, greater opportunity will exist for 

 environmental contamination by disease-produc- 

 ing agents of animal sources. In other words, as 

 time passes our pollution problems due to animal 

 wastes will become more serious. 



Research is underway but must, in the future, be 

 pursued more diligently on parasitic and infec- 

 tious diseases of cattle, swine, sheep, and poultry. 

 Many of these disease agents are capable of infect- 

 ing man as well as livestock; others, in the light 

 of our present knowledge, cause losses only in our 

 livestock populations. All, in one way or another, 

 affect the well-being of man. 



The following are a few specific examples of 

 animal diseases that are present^ receiving re- 

 search attention : brucellosis, leptospirosis, enceph- 

 alitis, tuberculosis, salmonellosis, and ornitho- 

 sis. This research will have as one of its prime 

 benefits the reduction of sources of environmental 

 contamination by infectious organisms. 



Research underway on parasitic diseases will 

 reduce environmental contamination in two dis- 

 tinct ways: First, by reducing environmental con- 

 tamination by parasite-infested animal wastes 

 through de\*elopment of methods to reduce para- 

 sitism in our livestock population : and second, by 

 reducing the opportunity for environmental con- 

 tamination by pesticides through development of 

 methods of reducing or eliminating parasitism 

 based on biological control, immunization, im- 

 proved management, or the more efficient use of 

 better chemicals. Much remains to be done in the 

 field of parasitological research, and adequate fa- 



cilities and an increase in overall effort are 

 urgently needed. 



Research is being pursued to define the toxico- 

 logical and pathological effects of insecticides, 

 herbicides, fungicides, and other agricultural 

 chemicals on livestock and poultry. 



Other current efforts include investigations on 

 the role of endoparasites in the transmission of 

 infectious diseases of livestock. 



Important primary considerations in disease 

 research are the adequate control and containment 

 of the disease-producing agents with which the in- 

 vestigator is working. This includes protecting the 

 researcher, protecting the integrity of the experi- 

 ment, and protecting the surrounding environ- 

 ment from inadvertent contamination. 



Although constant effort is being made to meet 

 these requirements, increased research and facili- 

 ties are needed to further assure the proper han- 

 dling of infectious or obnoxious aerosols and 

 animal and laboratory wastes associated with 

 research installations. 



Research has already accomplished much to re- 

 duce the hazards from environmental contamina- 

 tion by disease-producing organisms, and the 

 great plagues of the past are now, in most areas 

 of the world, only a matter of history. Even today, 

 however, this is not invariably true; and in our 

 modern society, constant vigilance against such 

 diseases as bubonic plague and smallpox are recog- 

 nized as an ever-present necessity. If the pressures 

 and concentration of modern society are not to re- 

 sult in the appearance of new epidemics or even a 

 revival of old ones, we must increase our research 

 efforts to consistently reduce pollution of our en- 

 vironment by disease agents. 



Plant Disease Agents 



Plant disease organisms continue to contaminate 

 the air, soil, and water of agricultural areas in 

 spite of extensive research to reduce and eliminate 

 them. Such contamination leads to the perpetua- 

 tion and spread of the organisms, with resultant 

 reductions in yield and quality of crops. For ex- 

 ample, the airborne rust diseases of wheat are 

 estimated to cause an average reduction of over 6 

 percent annually in the potential production of 

 that crop. Ear and stalk rots of corn cause over 5 

 percent average reduction of the potential corn 

 crop each year. These rots survive on the debris of 

 the previous corn crop. The potential cotton crop 



