Leishmaniosis is a tropical disease that affects mainly dogs in Spain. The “sand fly” (phlebotombus) sucks blood from a dog infected with leishmania, transforms them into infectious amastigotes and injects them into a healthy dog. Then two things can happen: 1. The dog has a good immune system and destroys the amastigotes or 2. It does not have a functional immune system (for whatever reason) or there are too many and the amastigotes infect the white blood cells, multiply inside the cell, destroy the white blood cell and each of the 4 new ones infect another 4 white blood cells, etc. Meanwhile healthy white blood cells try to destroy the infected white blood cells forming globulines which are too big for the small arteries in the body and they get stuck, causing skin lesions (ie at the tip of the ears, nose, feet), kidney damage, liver damage, intestinal damage etc. Untreated it will lead to death.