SURVIVAL OF PATHOGENS IN SOIL AND WATER 27 



actinomycosis in cattle, coccidiosis in poultry, hookworm infections, 

 trichinosis, enteric disorders in man, blackleg in cattle, and Texas fever. 

 To these may be added the botulinus organism and others producing 

 toxic substances, as well as bacteria, actinomycetes, and fungi that cause 

 plant diseases such as potato scab, root rots, take-all disease of cereals, 

 and damping-off diseases. 



Anthrax, a scourge of cattle and sheep, is a persistent survivor in 

 soil } spores of this organism are known to retain their vitality and viru- 

 lence for fifteen years. Anthrax survives particularly well in damp re- 

 gions, especially in soils rich in decomposing organic matter j the hay 

 and feed from these lands may transmit the disease to animals. The fact 

 that certain fields carry anthrax infection ("anthrax pastures") was 

 recognized in Europe long before the nature of the disease was known. 

 Human infection results from contact with diseased animals or animal 

 products. 



The anaerobic, spore-forming bacteria that cause gas gangrene are 

 widely distributed in nature. They are found extensively in soils and in 

 decomposing plant and animal residues. The causation of disease by 

 these organisms received particular attention during the first world 

 war, which was fought chiefly in trenches. 



Another important pathogenic anaerobe able to survive in soil for 

 long periods of time is CI. chauvoei, the causative agent of blackleg in 

 cattle J southern pastures are said to be better carriers of blackleg than 

 northern pastures. CI. tetani is also widely distributed in the soil and 

 appears to be associated with the use of stable manures. Wounds in- 

 fected with soil may lead, therefore, to the development of tetanus or 

 gas gangrene and must be treated accordingly. 



The botulinus organism not only may remain alive in the soil for a 

 long time (642), but it may also produce there a potent toxin that 

 causes much loss of water fowl and other wild life. Aeration of the soil 

 results in the destruction of this toxin by aerobic bacteria (742). 



Orgamsms that Survive for Brief Periods 

 . Other pathogenic bacteria, however, are able to survive in the soil 

 only for limited periods of time. They are eliminated sooner or later 

 from the soil, either because of their inability to compete with the soil 



