WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



47 



has been taken as an indication that infectious 

 bacteria might also be present. Coliform counts are 

 considered to be prime criteria of bacterial pollu- 

 tion of water. 



Coliform bacteria can enter streams by means 

 of sewage, animal wastes, or runoff from soils since 

 some coliforms persist in soil. A trained technician 

 using appropriate laboratory methods can dis- 

 tinguish between the form of bacteria coming from 

 animal effluent and those from soil. The former 

 are designated as fecal coliform bacteria. 



Streptococcal bacteria are also normally present 

 in fecal effluent of both animals and humans. 



Kenner, Clark, and Kabler (67) established 

 ratios between fecal coliform and fecal streptococci 

 for different pollution sources, as shown in table 

 4. 



Based on such information, water bacteriologists 

 used as a general guide that if this ratio is less 

 than one, the pollution is coming from nonhuman 

 sources; if the ratio exceeds 2.5, the bacterial 

 pollution is most probably coming from human 

 sources. Ratios between 1.0 and 2.5 suggest that 

 pollution is a mixture of human and nonhuman 

 sources. 



Fry (45) has conducted a number of bacterio- 

 logical examinations at various points on the 

 Potomac River system. He found that the Potomac 

 River at Shepherdstown, W. Va., has an average 

 f. coliform/f. streptococci ratio of 0.072: the 

 Shenandoah River at Charles Town, TV. Va., had 

 an average ratio of 0.24; and the Potomac River 

 at Point of Rocks, Mel., averaged 0.25. The Monoc- 

 acy River (Potomac tributary in Maryland) at 

 a point just below the city of Frederick, Md., had 

 an average ratio of 4.3G, showing that the pollution 

 was definitely from human sources. However, at 

 Great Falls on the Potomac (below Monocacy con- 

 fluence but just above Washington, D.C.) the aver- 

 age for the ratio was 0.042. Fry concluded from 

 these observations that most of the bacterial pol- 

 lution of the Potomac was coming from barnyards 

 and land runoff. 



Although fecal coliform and fecal streptococci 

 bacteria are rarely pathogenic, they do serve as 

 indicators that contamination has occurred and 

 that infectious organisms may be present. It is also 

 important to keep in mind that a variety of wild 

 animal species may contaminate streams with lep- 

 tospira and other organisms. 



Table 4. — Average contents of f. coliform and 

 f. streptococci in fecal wastes of various animals, 

 and ratio off. coliform to f. streptococci 



Vertebrate 



F. coliform 



F. strepto- 

 cocci 



F. coliform- 



f . strep- 

 tococci ratio 



Millions 



Cow __ 0.23 



Pig 3.3 



Sheep 16.0 



Poultry 1.3 



Turkev .29 



Duck.. 33.0 



Man 13.0 



Millions 





1.3 



0.18 



84.0 



.04 



38.0 



.43 



3.4 



.38 



2.8 



.10 



54.0 



.61 



3.0 



4.33 



Other infectious agents of animals that may pol- 

 lute streams are as follows : Anthrax, brucellosis, 

 coccidiosis, encephalitis, erysipelas, foot rot, histo- 

 plasmosis, hog cholera, infectious bronchitis, mas- 

 titis, Newcastle disease, ornithosis, transmissible 

 gastroenteritis, and salmonellosis. Such agents may 

 subsequently infect other animals, or in the case of 

 some disease producing agents, even humans. 



In late May and early June 1965, 18,000 people 

 in Riverside, Calif., were infected with Salmonella 

 typh/murhim that had entered into the city's water 

 supply. Drinking water for Riverside comes from 

 deep wells, a source presumed to be beyond bac- 

 terial contamination. No one has satisfactorily ex- 

 plained how salmonella got into this water supply. 



In view of our large livestock population and 

 the number of livestock diseases that could afflict 

 man, the actual number of infections from drink- 

 ing water is exceedingly low. During the 15-year 

 period, 1946-60, there were only 16 human deaths 

 attributable to waterborne agents — eight from ty- 

 phoid fever, four from chemical poisoning, and 

 four from infections other than typhoid. This ex- 

 cellent record is due to the high level of activity 

 in protecting animal health and curbing dissemina- 

 tion of animal diseases; and intense vigilance in 

 monitoring drinking water supplies. 



Encephalitis is the most serious mosquito-borne 



disease in the United States. It is endemic in virtu- 

 ally all irrigated regions, but certainly not re- 

 stricted to these. Epidemics occur in scattered 

 irrigated areas every year. Such outbreaks can re- 

 sult in hundreds of eases and semes of human 

 deaths. Serious epidemics frequently kill hundreds 

 of horses. 



In recent years, encephalitis outbreaks hav< 

 curred in irrigated areas in the Texas High Plains, 



