I dont have experience with it. I had a girl years ago who they suspected may have had it, but it turned out to be a severe kidney infection if I remember right (its been a LONG time)
what I DO know about Lepto is that it is zoonotic, meaning your boy could have infected you with it. If he is positive, they will end up needing to treat not only your boy, but also your family members and the clinic staff that took care of him.
Is he vaccinated against Lepto? I seem to remember reading that Lepto should actually be vaccinated against twice yearly if you live in an area where it is a concern. It was something about the fact that the Lepto portion of the vaccine protects poorly and doesnt last as long. Also, there are many strains of Lepto, and the vaccine protects against only the 4 most common. Some vaccines only protect against 2.Sorry I cant be of more help