An HIV-free generation is possible. But foreign aid cuts are threatening to unravel decades of progress.

Ismail Harerimana grew up in Uganda not knowing why he was always sick.

His childhood in the 1990s was a string of recurrent infections: malaria, diarrhea, headaches, and skin rashes. By 14, he was scarily thin, at which point doctors put him on a new medication that seemed to help. It was for…