Evaluation of a skin sensitivity test for the diagnosis of toxocariasis

As part of a programme for determining the epidemiology of toxocariasis in man further evidence on the sensitivity and specificity of the toxocaral skin test was sought by 3 means:— Persons in whom a diagnosis of toxocariasis had been proved were sought and the skin test was performed on them. The result was positive in all cases. The specificity of the test was further assessed by performing it on 122 patients with proved non-toxocaral helminthic infections. 2.5% reacted positively, a proportion not significantly different from that in apparently healthy persons. Further information was sought on the extent to which seemingly healthy persons have been infected with toxocariasis as indicated by the skin test. Among 156 persons so tested 1·35% reacted positively. In a previous similar survey 2·1% of 329 reacted positively, a proportion not significantly different from that in this study, and indicating that among apparently healthy persons approximately 2·0% have been infected with toxocariasis in the past. Tese results further confirm the value and specificity of the skin test and indicate that a significant number of apparently healthy persons have been infected with toxocariasis.