Observations Upon Complement Fixation in Experimental Amebiasis in Dogs.

Abstract

The writer demonstrated the presence of complement fixing bodies in the blood serum of individuals infected with Endamoeba histolytica and subsequently, , , , reported the results obtained with a complement fixation test in cases of human amebiasis and in normal individuals, together with the technique of the test. These observations have been confirmed by Spector, Fernandez, Heathman, and Sherwood and Heathman. The observations here reported were undertaken to throw further light upon the phenomenon of complement fixation in amebiasis, using the dog, an animal that Faust has shown is easily infected with Endamoeba histolytica and in which the lesions produced by this parasite are comparable to those occurring in intestinal amebiasis in man. Alcoholic extracts of cultures of Endamoeba histolytica were used as antigens. Tests were made upon 29 dogs infected with Endamoeba histolytica and in all but one (96.5%) a positive complement fixation reaction developed in the blood serum. In the dog giving a negative reaction death occurred 7 days after colonic inoculation from a very severe amebic colitis. Of the dogs giving a positive reaction, 21 (75%) gave a 4+ reaction; 3 (10.7%) gave a 3+ reaction; 2 (7.1%) gave a 2+ reaction; and 2 (7.1%) gave a 1+ reaction. Of the 28 dogs giving a positive reaction 22 died and 5 were sacrificed, 3 while still suffering from intestinal amebiasis while 2 had recovered from the infection. Of the 22 dogs that died, all showed typical amebic ulcerations in the colon and in all motile forms of Endamoeba histolytica were found in the lesions. The 3 dogs killed while still suffering from the infection showed both healed and active amebic lesions in the colon and motile Endamoeba histolytica were present in the active lesions.