Medical exams for z-visa

I´m in the final stages of getting my z-visa to work in an international school in China. The school where I´ll work sent me the invitation letter and visa information and I´ll pick up the z-visa this Wednesday for my family (husband and 2 children) and I. The school never told me that I need to present papers showing medical exams, HIV, and Hepititus A. Is this needed for the Z-visa in Colombia and/or to leave Colombia?What form do I fill out? The school did not send me this? When I asked they said that in many Countries including the U.S., these exams are not required. They coudn´t tell me much. Even the lady in the Colombia Embassy in Bogota couldn´t confirm this or give me the medical forms to fill out but i saw it written in the internet (Chinies embassy in Colombia) Please confirm information about the medical check requirement for the z-visa leaving Colombia. We will be stopping in the United States for one week before going to Qingdao, China. My kids have duel citizenship (U.S./Colombian). I´m a U.S. Citizens and my husband is Colombia.
Thanks! Stacy