Detection of a circulating antigen of Toxocara canis in the sera of naturally infected men and experimental animals

Circulating antigen of Toxocara canis was demonstrated in the sera of experimentally infected rabbits and in patients suspected of the infection. The antigen appeared in the circulation between days 7-14 post infection in animals infected with 5,000 to 20,000 embryonated eggs of the parasite and on 3rd-4th day in rabbits infected with 50,000 eggs. Afterwards, it was present in the sera at irregular intervals until the end of observation period, either free or in complexes with specific antibodies of the IgG or IgM class. Western-blot analysis of infected sera detected two components of the antigen at approximately 32 and 92 kDa. Detection of the antigen in examined serum samples may aid the diagnosis of toxocaral infection, particularly in cases suspected of unspecific reactions in the tests for antibodies.