Low avidity antibodies in diagnosis of recent experimental schistosomal infection.

ELISA test was used to measure both of low- and high-avidity specific IgG against soluble S. mansoni egg antigen, to differentiate between S. mansoni experimentally infected mice with recent and chronic infection. Mice were infected with 100 S. mansoni cercariae and serum samples were obtained and tested 4, 6, 8, 10, 12, 14 and 16 weeks after infection. The results showed that there was a statistically significant difference between low- and high-avidity specific IgG in experimentally infected mice at 4, 6, 8, and 10 weeks after infection (recent infection). On the other hand, no difference was found in those with chronic infection (12, 14 and 16 weeks after infection). From these results it was concluded that the comparison of low- and high-avidity specific IgG levels was able to differentiate between recent and chronic experimentally infected mice with S. mansoni.