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A cold-active hemagglutinin for trypsinized human type "O" erythrocytes (CAH) from blood of chickens with acute Plasmodium gallinaceum malaria was found to be associated with 19 S and 7 S globulin fractions of malarious chicken blood, but cleavage with 2-mercaptoethanol indicated that it was primarily of the IgM class of antibody. In serologic tests CAH reacted with trypsinized erythrocytes, and anti-chicken globulin. It did not react with other of the antigens or antibodies detected in the blood of malarious chickens. When the absorbed and eluted CAH was injected into normal chickens it produced an anaphylactic-like shock and caused a 25% reduction in red blood cell counts within 48 hours. Plasma samples collected during this interval showed signs of hemolysis. Reactions of blood cells from the recipient birds with fluorescein conjugated anti-chicken globulin indicated that CAH reacted with erythrocytes. The absence of fluorescent activity 3 days after injection suggested that these erythrocytes had been removed from the circulation. When normal chickens were injected with trypsinized autologous blood cells, CAH was detected within 3 days. The agglutination test again was active at temperatures below 22 degrees C and was negative when tested at 37 degrees C. In these birds the appearance of CAH was accompanied by reductions in red blood cell counts and by hemolysis. The results of these experiments suggest that CAH was not stimulated by plasmodial parasite antigen, but rather by autoantigens, which appear to be common to heterologous animal species, and which were in some manner expressed by the presence of the intracellular parasites, or by trypsin treatment. The experiments further suggest that this autohemagglutinin was partially causal of malarial anemia. The presence of other anemia factor(s) was indicated by anemia following injection of plasma that had been absorbed free of CAH.

Four serologic techniques for the diagnosis of visceral larva migrans caused by Toxocara canis, namely indirect hemagglutination (IHA), bentonite flocculation (BF), enzyme-linked immunosorbent assay (ELISA), and double diffusion in agar (Ouchterlony), were evaluated using sera sent to the Center for Disease Control from patients with a presumptive diagnosis of visceral larva migrans (VLM). Patients having 5-6 of the clinical or laboratory criteria for VLM were designated as cases while those with 0-2 criteria served as controls. The sensitivity of the ELISA was 78.3% compared to 18.2%, 25.8% and 65.2% for the IHA, BF, and Ouchterlony, respectively; the sepcificity of all four tests was greater than 92%. The predivtive value of positive test was greater than 85% for all tests except the IHA, while the predictive value of a negative test was greater than 85% only for the ELISA. The results of a ELISA were reproducible in different laboratories. Based on these findings, the ELISA using a larval antigen appears to be the serodiagnostic method of choice for VLM.