The investigators will strictly comply with widely recognized international texts and codes of practice including the Helsinki agreement. In this project one patient cohort will receive ETS and the other CT. However both groups will be encouraged to proceed regularly with their drug treatment and to present difficulties that they may encounter in doing so. For the project period, the project will meet the costs of ART for the cohorts. Patients' biological samples will be collected and used only after written consent from the children's caretaker. All specimens will be coded to protect the identity of patients and to ensure confidentiality. Patients will be recruited in a consecutive manner without regard to race or other exclusion considerations. Confidentiality will be assured by using codes for patient identification, and confidentially laws will be strictly observed when processing human clinical information. No patient identifying information will be published or available after the requisite clinical data has been collected, and consent will be obtained for the use of all data and tissues. Data will be accessible only to members and coordinators of the tissue procurement facility and research team, under approved guidelines.