the distribution of infectious diseases. Scientific 

 interest is usually directed at the whole problem 

 with little attention given to the water phase. 

 Some diseases are so water oriented that attention 

 is directed at the quality and characteristics of the 

 water environment as a factor in the distribution 

 of disease. This interest is increasing as the ecol- 

 ogy of waterborne diseases becomes of greater 

 concern. 



Enteric microorganisms, including the vibrios 

 and amoebae, have a long record as water pollut- 

 ing agents. Chlorination, filtration, and other water 

 treatments are directed at making water safe, but 

 total microbial elimination in natural water appears 

 to be an impractical procedure for man, let alone 

 livestock. 



The spread of animal infections through fecal 

 contamination of the environment is a constant 

 threat, but epidemiological evidence should sup- 

 port more criteria which directly relate specific 

 diseases to water. The Escherichia- Aerobacter 

 group of enterics is so widely distributed in nature, 

 feed, water, and the general environment, that 

 contamination of the intestinal tract can hardly 

 be avoided. When they escape from these innocu- 

 ous locations, as they sometimes do, to cause 

 urinary disease, abscesses, and mastitis, they are 

 very potent pathogens. Their invasiveness is low 

 and unless some stress is involved infections are 

 generally regarded as accidents. In contrast, Sal- 

 monella are more invasive and the carrier state 

 is easily produced and persistent, but often with- 

 out any general evidence of disease. This means 

 that waterborne epidemics follow the introduction 

 of specific microorganisms into the environment; 

 e.g., where untreated sewage continually enters 

 the water supply. 



Water criteria directed against pathogenic mi- 

 croorganisms are divisible into two general areas 

 of concern. The purely mechanical spread of mi- 

 croorganisms by way of water is very important, 

 since desiccation is destructive of most living 

 agents. The mobility of water also increases the 

 chance of spread with greater dispersion of diluted 

 but infective doses of pathogenic organisms. There 

 is a more important aspect of water and water 

 management which deserves greatly expanded 

 study. The virulence of microorganisms is in- 

 fluenced by their environment. When a pathogen 

 enters an aqueous environment, its ability to infect 

 a new host may be influenced by water quality. 

 The reports of waterborne disease substantiate 

 this situation and serve as the principal basis for 

 criteria. With the substantial scientific base for 

 chemistry, soil microbiology, ecology, and geology 

 available to the agricultural community, the ob- 



vious presence of water-related disease in one farm 

 area or region and its absence in another should 

 serve as a basis for comparison. 



One of the best examples of water-related dis- 

 ease is bacillary hemoglobinuria, caused by an 

 organism found in western areas of North and 

 South America. This organism resembles Clos- 

 tridium novyi, and may be classed in several spe- 

 cies, CI. hemolyticum, CI. sordellii, the Newhall 

 strain, and possibly others. It has been linked 

 with liver fluke injury, but is not dependent on the 

 presence of liver flukes. Once the disease has been 

 properly diagnosed, the characteristic liver infarct 

 is not easily confused. The particular concern has 

 been the spread of this disease to new areas in 

 the Western States. Far from an indiscriminate 

 spread, each new premise is like the endemic areas 

 which have alkaline, anaerobic soil-water envir- 

 onments in which the organisms have a soil phase 

 outside the host animals. This disease may make 

 its appearance in new areas of the West when 

 these areas are cleared of brush and irrigated. To 

 avoid this problem, western irrigation waters 

 should be managed to avoid cattail marshes, hum- 

 mock grasses, and other environments of pro- 

 longed saturation. The significant ecological dis- 

 tinction is measured by pH which must persist 

 in alkaline ranges usually around pH 8.0. 



The anthrax organism, Bacillus anthracis, is 

 found in a soil environment above pH 6.0. The 

 organism forms spores which, in the presence of 

 adequate soil nutrients, again vegetate and grow. 

 The spore is most likely the cause of infection, 

 coming from an "incubator area" of killed grass 

 found in the pasture where the loss occurred 

 (183). Some very rich alluvial soils may lack 

 the grass-kill feature, but these soils at the time 

 of losses are powdery and dry. The killed grass 

 is brown rather than blackened, a significant dif- 

 ference from water-drowned vegetation in general. 



The spread by water of disease caused by drink- 

 ing water containing spores has never been proved. 

 Bits of hide and hair waste may be floated by 

 water downstream from manufacturing plants, but 

 very few outbreaks have been reported through 

 this source. Numerous outbreaks studied in recent 

 years have always had the "killed grass" potential. 

 The organism and spore are nonmotile and sink 

 in quiet water to the mud, where they are de- 

 stroyed by biological competition. It is a soil or- 

 ganism not adapted to survival in water. 



A relatively new and widespread disease entity 

 in the United States, leptospirosis, is probably 

 the most intimately water-related disease problem 

 today. Criteria for the control of this disease are 

 simple with some exceptions. The pathogenic 



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