Visceral larva migrans--an immunofluorescent examination of rabbit and human sera for antibodies to the ES antigens of the second stage larvae of Toxocara canis, Toxocara cati and Toxascaris leonina (Nematoda).

Precipitates were demonstrated in vitro at the orifices of the second stage larvae of Toxocara canis and T. cati when placed in sera derived from rabbits infected with these nematodes. Cross-reactions occurred between these two species. Furthermore, these precipitates occurring at the oral, excretory pore and the anal orifices of these larvae were shown to be of a specific antibody nature by the use of the direct fluorescent antibody (Coons) staining technique. The second stage larvae of Toxascaris leonina did not react in this way when examined in the above-mentioned experimental system, or in sera or globulins derived from rabbits infected with T. leonina. Human sera, taken from clinically suspect cases of visceral larva migrans, were examined in this manner (q.v.). Comparable results were obtained, and it was possible to determine whether fluorescent antibodies were present, and to use this information as an aid to the clinical diagnosis of this disease. The significance of these findings in relation to the aetiology, pathogenesis and immuno-diagnosis of visceral larva migrans is discussed.