LITERATURE CITED 



Earp, B. J., C. H. Ellis, and E. J. Ordal 

 1953 . Ki dney disease in young 



salmon. State of Washington 

 Department of Fisheries, Special 

 Report Series, No . 1 . 



ADDENDUM 



A PROCEDURE FOR THE DETECTION OF ACID- FAST BACTERIA IN FISH: 

 A COMPARATIVE STUDY OF DIGEST -CONCENTRATE VS. SMEAR TECHNIQUE 



By 



Richard L. Westgard 

 State of Washington Department of Fisheries 



ABSTRACT 



A method has been developed to detect the presence of 

 acid-fast organisms and to determine their relative number in 

 fish tissue. This digest-concentrate method detects the presence 

 of small numbers of organisms and those which are grouped in 

 isolated tubercles which might escape detection with the standard 

 smear technique . A comparative study was made between this 

 digest -concentrate and the standard smear technique. Of 1,234 

 fish livers examined, 41 or 3.3 percent were positive by the smear 

 method and 56 or 4.5 percent were positive by the digest -concentrate 

 technique. This is a 36.4 percent increase in positives of the latter 

 over the first. A combination of both methods gave a total of 77 

 positives or 6.2 percent of the number examined; a yield of 87.9 

 percent increase over the smear method and a 37.8 percent increase 

 over the digest-concentrate. 



In order to conduct a survey of the in- 

 cidence of acid-fast bacteria in salmon and 

 steelhead trout in the Columbia River Basin it 

 was recognized that a more accurate and exped- 

 ient method of detecting the presence of these 

 bacteria in fish tissue would be desirable. This 

 paper deals with such a method. 



Acid-fast bacteria produce a systemic in- 

 fection in salmon and steelhead trout with heavy 

 concentrations of the organisms usually found in 

 the liver . The liver was used exclusively for 

 this study, because this tissue is conveniently 

 obtained, handled and stored . 



Gross observation and pathological studies 

 of the diseased livers have shown that acid-fast 

 bacilli tend to form in localized nodules instead 

 of disseminating throughout the tissue. Unless 

 gross infection is encountered, the bacilli would 

 often be undetected by the usual methods of daub- 

 ing small bits of tissue on a slide, or crushing 

 tissue between slides . To overcome this the 

 whole liver was liquefied producing an homogen- 

 eous distribution of bacteria. The concentration 

 of an aliquot of the liquid yielded a known percent- 

 age of the total number of organisms per gram of 

 liver by this method. 



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