New technologies for use in the surveillance and control of yaws

In the Republic of Ghana, treponemal antigen tests performed on finger-prick blood from patients with yaws proved to be as sensitive as those tests performed on whole sera, and this mode of collection was more economical and acceptable than venipuncture. Under field conditions, dark-field microscopic examination of suspect yaws lesions was difficult as compared with collection of serous exudate in heparinized capillary tubes examined later in a reference laboratory. Direct staining of lesion exudate fixed on microscope slides with fluorescein-conjugated human or mouse monoclonal antibody against Treponema pallidum was more sensitive than dark-field examination. However, these techniques could not distinguish between the early lesions of venereal syphilis and those of yaws. An equally sensitive technique used a cloned segment of the T. pallidum (Nichols strain) genome to detect homologous DNA in lesion exudate fixed on nitrocellulose filter paper. The fixation of lesion exudates on microscope slides or nitrocellulose papers may prove to be the easiest method of collecting and transporting such materials to reference laboratories.