Drugs & Diagnostics for Tropical Diseases (DDTD). Scientists united against neglected tropical diseases, developing treatments and diagnostics for #NTDs. Drugs & Diagnostics for Tropical Diseases (DDTD) is a unique non-profit (501c3) venture based in Sa At DDTD we embrace the ideal of eliminating diseases that do not belong to the 21st century. Diagnostics are critical to support all stages of disease elimination programs. Diagnostics are used to (1) map a disease and plan the fight – the first step towards eliminating a disease, (2) monitor the progress of interventions such as mass-drug administration or vaccination programs, (3) decide when interventions can be safely halted, and (4) implement post-intervention surveillance program to ensure that the disease is not reemerging.