FURTHER TOXOCARA SKIN SENSITIVITY TESTS IN ANIMALS EXPERIMENTALLY INFECTED WITH TOXOCARA CANIS

4 rhesus monkeys were infected with 200, 100, 50 and 20 embryonated eggs of T. canis respectively and tested regularly with an intradermal Toxocara sensitivity test. Their absolute eosinophil levels were estimated weekly. Negative reactions with the antigen were obtained in all the monkeys before infection and with the saline control used throughout the experiment. Positive reactions occurred after variable periods following infection in all, although the response in those monkeys given smaller numbers was less regular, more transient and occurred later than in those given larger numbers. In those given small numbers, conversion of the skin test from negative to positive occurred before the eosinophil level had altered. The experiment shows that the skin tests converted after infection with T. canis in experimental animals, and suggests that a positive skin reaction is seen even when other signs of helminthic infection are absent; the conversion time depends upon dosage. © 1969 Royal Society of Tropical Medicine and Hygiene.