Failure of penicillin treatment of yaws on Karkar Island, Papua New Guinea.

The endemic treponematosis yaws remains a significant cause of morbidity in many tropical countries, despite mass treatment campaigns to eradicate it. An outbreak of yaws in Marup village on Karkar Island, Papua New Guinea in 1988 provided an opportunity to monitor the outcome of treatment with penicillin over an extended period. Thirty-nine children with clinical yaws (6% of 632 examined) were monitored clinically and serologically, for nearly two years after mass treatment of all villagers with the World Health Organization recommended dosages of benzathine penicillin. Lesions resolved within one month of treatment in all but four (10%) children, three of whom were initially successfully retreated. Before treatment, the Venereal Disease Research Laboratory (VDRL) test result was reactive in 67% of the children and treponema-specific IgM antibody test results were reactive in 41%. Within six months of treatment, of those reactive, the VDRL titer decreased significantly in 25 (96%) of 26 and IgM antibody test results became negative in 13 (81%) of 16 children. However, by the end of follow-up, 11 (28%) of the 39 children had developed clinical and/or serologic evidence of relapse. In these children, response to further treatment was slow and, in three, evidence of active infection persisted or recurred, despite repeated courses. Exogenous reinfection was unlikely in this isolated community, in which the occurrence of yaws was closely monitored after universal treatment. Treatment failure was most likely to have been due to reduced susceptibility to penicillin of Treponema pallidum subsp. pertenue.

Treponema pallidum western blot: comparison with the FTA-ABS test as a confirmatory test for syphilis.

We developed a Treponema pallidum Western blot and compared the results with Treponema pallidum particle agglutination (TPPA) and fluorescent treponemal antibody absorption (FTA-ABS) tests. The Western blot was deemed reactive if the serum reacted with at least three major antigenic bands (TpN47, TpN44.5, TpN17, TpN15). The sensitivities of the Western blot, TPPA and FTA-ABS, were all 100% and the specificities of the Western blot, TPPA and FTA-ABS were 100%, 100% and 94.5% respectively. In 52 problem sera, reactive in only one treponemal test, the agreement between the Western blot and TPPA (61.5%) was significantly better than between Western blot and FTA-ABS (38.5%). The individual sensitivities and specificities of TpN47, TpN44.5, TpN17, TpN15 were 100%, 100%, 96%, 100% and 20%, 96%, 100%, 100% respectively. We conclude that the Western blot is a useful additional confirmatory test or alternative to the FTA-ABS and that a more sensitive and specific criterion for the Western blot would be reactivity with TpN15 and two of the three other major antigens.

Modified indirect hemagglutination test for detection of treponemal antibodies in finger-prick blood.

A modified indirect hemagglutination test for the detection of treponemal antibodies was developed for use with finger-prick blood. By using paired serum and absorbed finger-prick blood from 58 patients from an area previously endemic for yaws and 12 patients without yaws, the modified hemagglutination test was compared with a hemagglutination test for Treponema pallidum and the fluorescent treponemal antibody absorption test. The modified hemagglutination test showed 100% specificity and an overall agreement of 96.5% with the hemagglutination test for T. pallidum and 94.8% with the fluorescent treponemal antibody test. The modified hemagglutination test appears to be a simple and economical test that is suitable for use in large epidemiological surveys for yaws.