A roof, walls, windows and net in the windows to keep mosquitoes away at night, and avoid malaria and similar mosquito transmited illness. I'd add Chagas-Mazza that is tranmited by other bug but it's probably endemic there.

Also, tap water or at least a well.

During tje first year, children get like 20 or 25 vaccines. Some of the ilness are very rare and they may not know them, but other are just severe diarhea caused by a common bacteria. And add antibiotics for other common problems.