EEPOET OF THE BUKEAU OF ANIMAL INDUSTRY. 85 



ORDINARY LIME AS A DISINFECTANT IN HOG CHOLERA AND SWINE 



PLAGUE. 



Experiments made by Liborius * in Germany have demonstrated 

 that the bacteria of typhoid fever and cholera in man are quite readily 

 destroyed with ordinary slaked or unslaked (powdered) lime. Ex- 

 periments made during the summer of 1887 and subsequently, in the 

 Bureau laboratory, with lime upon the virus of hog cholera, have 

 been very satisfactory. In fact, the results were sufficiently posi- 

 tive to warrant its use in place of the corrosive sublimate recom- 

 mended in the preceding report. 



Lime has many advantages over the usual disinfectants. It is 

 cheap, is easily obtained and prepared, and may be used with im- 

 punity, as it has no poisonous properties. Nor is the soil injured by 

 the addition of a small percentage of lime. The method which was 

 followed out in testing its germicide properties was mainly that used 

 by Liborius. 



Bacteria of hog cholera free from any organic or inorganic matter 

 are destroyed within one hour by .03 per cent, of lime; in other words, 

 by lime water diluted to one-fourth its original strength (. 12 per cent. ). 



When the same bacteria are suspended in bouillon as much as 

 .08 per cent, is necessary to destroy them. When a considerable 

 quantity of coagulated albumen, as much as is contained in boiled, 

 unfiltered beef infusion, was present, and in addition a quantity of 

 egg albumen equivalent to two eggs in a liter, the liquid requires 

 between .3 and .4 percent, of lime before the bacteria are completely 

 destroyed. 



These experiments have reference to the disinfection of the dis- 

 charges of diseased pigs, in which the amount of organic matter can 

 hardly be so great as in the albuminous liquid above mentioned. It 

 will be seen that as this increases in amount a larger per cent, of lime 

 is required. The lime produces a flocculent precipitate which sub- 

 sides, leaving a perfectly limpid supernatant liquid. The precipi- 

 tated portion of lime very probably becomes inert. 



Experiments were made with soil in the same way. A rich loam, 

 to which large numbers of hog cholera bacteria suspended in simple 

 bouillon were added, was completely freed from living bacteria within 

 one day by adding one-half per cent, of lime by weight to the soil 

 and mixing the two together. The soil had been previously steril- 

 ized before the hog cholera bacteria were added. The lime was used 

 in the form of a 5 and 10 per cent, milk of lime. 



In the practical application of lime we may say in general that it 

 should be used in place of mercuric chloride (corrosive sublimate) 

 wherever possible. On wood-work it will be efficient as a whitewash. 

 In infected pens the soil should be covered either by powdered lime 

 or slaked lime in a thin layer. The lime-water will percolate into the 

 deeper layers of the soil and destroy any bacteria which have pene- 

 trated into them from the surface. 



The experiments on the vitality of hog cholera virus in the soil are 

 not sufficiently comprehensive as yet to be made a basis for practical 

 deductions. But, taking all the evidence, it is safe to say that a period 

 of nine months is the maximum and three the minimum time that need 

 be allowed for infected pens and grounds to become safe for occupancy 

 when no disinfection is practiced. Lime as a whitewash on wood- 



' * Zeitschrift fur Hygiene, II (1887), p. 15. 



