Hi,
I do not have kids, but I do think you should take care of Malaria, because it's what hits newcomers more than anything else. Either you vaccinate him, or use preventive measures can be better advised by a medical person.
However, since he is just 2 years old, important will be where he will live, especailly things to do with hygiene, other kids, or other people he will be living with in the home, and neighborhood. It may include the places you may visit. If you take care of the bacterias, and contageous infections, you should have a good start...
I hope that will help. Have a nice stay when you come, and hope all goes well for you.
God is good, all the time...
MJJoseph!