Complex sentence: The ARCH (Applied Research for Child Health) Project replaced the ADDR Project and expanded its work further into roles of development activities on the reemergence of previously-controlled infectious diseases and the emergence of newly-described infectious diseases.
Split into simpler sentences: The ARCH (Applied Research for Child Health) Project replaced the ADDR Project and expanded its work further. Ongoing research studies roles of development activities on the reemergence of previously controlled infectious diseases and the emergence of newly described infectious diseases.