Chapter XVI — 185 — Sanitary Aspects 



tion, (V) Voges-Proskauer test, and (C) utilization of citrate as a sole 

 carbon source (Parr, 1939). E. coli was found only in feedy fishes taken 

 relatively near shore. Aerohacter species were more abundant than E. coli 

 in the intestinal tracts of fishes. From the survey it was concluded that 

 E. coli or other bacteria which ferment lactose with gas production do not 

 constitute part of the normal intestinal flora of marine fishes, although, if 

 ingested, such bacteria may survive for considerable periods of time. 



The absence of E. coli from Buzzards Bay and Vineyard Sound near 

 Woods Hole was reported by Browne (191 7). E. coli was found in the 

 intestines of only 39.8 per cent of 93 scup which he examined. Clostridium 

 welchii was found in 30. i per cent of the fishes. The presence of these bac- 

 teria in the fishes' intestines seemed to be a function of the amount and 

 type of food present. 



After noting that the bacteria in fewer than half of the 72 offshore 

 fishes which he examined produced gas in lactose broth, Gibbons (1934^) 

 concluded that E. coli and Aerohacter aerogenes are present only in fish from 

 contaminated water. He found E. coli in only 6.9 per cent of the positive 

 lactose broth cultures. Griffiths and Fuller (1936) detected only a few 

 E. coli in commercial fish, from which they concluded that the E. coli con- 

 tent of fish is largely due to handhng. Additional literature reviewed by 

 Griffiths (1937) indicates that E. coli is not a normal intestinal inhabi- 

 tant of marine fishes. 



The intestinal contents of sea fowls are generally reported to be free 

 from coliform bacteria except in certain cases where there is evidence that 

 the fowls have been feeding in polluted waters. Little is known regarding 

 the intestinal flora of marine mammals. E. coli does not appear to be a 

 normal inhabitant of the intestines of seals in captivity. 



The general absence of coliform bacteria in the sea except in areas 

 known to be polluted with sewage confirms the validity of the test for coli- 

 form bacteria as an indicator of sewage poUution. It follows that, wher- 

 ever large numbers of E. coli are found in the sea, the possibility exists 

 of typhoid, dysentery, and cholera organisms also being present. Al- 

 though epidemics of these gastro-intestinal diseases have never been 

 traced to bathing beaches, outbreaks of typhoid have been traced to 

 infected oysters. 



Coliform bacteria are commonly present in small inland lakes which 

 are more subject to poUution than the ocean. The coliform bacteria count 

 of the hypolimnion of lakes was found by Taylor (1941) to be very low 

 and relatively constant. More coliform bacteria were found in the epi- 

 limnion where the numbers were greatest in summer and autumn, despite 

 less terrestrial pollution during the summer. About 70 per cent of the 

 coliform bacteria isolated from lakes by Taylor were E. coli types. 



Other sanitary problems of hydrobiological interest are reviewed by 

 Whipple (1927), Prescott and Winslow (193 i), Nikitinsky (1938), 

 Gainey (1939), and Suckling (1943). 



Bacteriology of shellfish: — Oysters, clams, and mussels are often 

 eaten raw or in a partially cooked condition. As a result, numerous cases 

 of typhoid fever and Asiatic cholera have been traced to the ingestion of 

 contaminated shellfish. Though normally free from dangerous bacteria in 

 clean water, the pollution of bays and estuaries with unpurified sewage 

 renders shellfish a potential source of infection. According to Prescott 

 and Winslow (1931) who reviewed the literature on this subject, '*In 



