Studies on Trachoma
VII. Isolation of a Mixture of Type 1 and Type 2 Trachoma Strains from a Child in Saudi Arabia
A strain of trachoma isolated from a 3-year-old girl in Saudi Arabia initially showed antigenic characteristics of both types 1 and 2 by toxin-protection tests in mice and by fluorescent-antibody tests. Pure types 1 and 2 were separated from the parent strain in four experiments with limiting dilutions in eggs. We concluded that this strain was therefore a mixture, rather than a hybrid; there is no evidence from this laboratory nor in published reports that either phenomenon has been reported previously.