The answer is macrophages. They either actively invade these leukocytes or are phagocytosed, divide in the cells and cause lysis. The promastigotes that invade these leucocytes are transformed into amastigotes in the macrophages. These amastigotes continue attacking other healthy macrophages while others migrate to the mid gut.
This startle reflex (aka moro reflex) is/was present in us as newborns.
It's triggered when there's an unexpected reaction. Example: Loud noise, sudden movement.
The baby will tighten his/her body, fling out arms, sort of like giving him/herself a hug. It happens because the baby is trying to protect itself from harm.
It normally leaves thanks to the mother's care, normally 6 weeks after the newborn is born.