Of course, the child is not promiscuous. How did the child become HIV+? Is the blood supply contaminated?
The family was traveling in Europe when the child suffered an injury requiring a blood transfusion. Some Western European countries are surprisingly not very good at screening their blood donors. In this case, it was the Netherlands.
Treatment for hemophilia involves concentrates of clotting factors from multiple donors per dose, rather tthan the single donor in the usual blood transfusion. Increasing the number of donors used to make the product magnifies the risk of each dose. Hemophiliacs are therefore e hardest hit.