JOURNAL OF AGRKUltAL RESEARCH 
DEPARTMENT OF AGRICULTURE 
Vol. V Washington, D. C., January 31, 1916 No. 18 
EFFECTS OF REFRIGERATION UPON THE LARVJB OF 
TRICHINELLA SPIRALIS 
By B. H. Ransom, 
Chief , Zoological Division , Bureau of Animal Industry 
INTRODUCTION 
Prior to recent investigations, the first of which were briefly reported 
in a short article which appeared about two years ago (Ransom, 1914), 
it had been generally accepted as an established fact that the larvae of 
Trichinella spiralis are very resistant to cold and that they survive 
exposure to temperatures much below the freezing point of water. In 
the article referred to, however, it was shown that former ideas con¬ 
cerning the resistance of trichinae to cold were erroneous, and that as a 
matter of fact low temperatures have a very pronounced effect upon 
the vitality of these parasites. As a precise knowledge of the effects of 
refrigeration upon trichinae is of considerable importance, an extended 
investigation has been made, the results of which are recorded in the 
present paper. 
HISTORICAL SUMMARY 
The following summary covers all of the published reports of experi¬ 
mental work on the effects of cold upon trichinae so far as they could be 
traced in the literature. 
Leuckart (1863a, p. 120) states that trichinae are in the highest degree 
resistant to cold. He exposed some trichinous meat outdoors during cold 
January weather (—16° to—20°R.; —4 0 to—13 0 F.; —2o°to— 25 0 C.) 
for three days and nights. After thawing the meat, he fed it to a rabbit, 
which died a month later and was found to be very heavily infested with 
trichinae. In another publication (1866a, p. 91) Leuckart notes that 
the place in which this meat was kept was somewhat protected, and it 
may therefore be presumed that the temperature to which the meat was 
actually exposed was probably not as low as indicated by the figures given. 
Leuckart remarks, however, that the meat was solidly frozen throughout. 
Fiedler (1864, p. 466) exposed the leg of a trichinous rabbit to an out¬ 
door temperature of —15 0 to —17 0 R. (—1.75 0 to —6.25° F.; —18.75° 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
cc 
(819) 
Vol. V, No. 18 
Jan. 31,1916 
A— 19 
