The patient’s nose looks like it has melted away. Several years ago, she noticed an unsightly ulcer on her face. It eventually healed, but it returned with reinforcements. Together, the onslaught of ulcers slowly ate away at the tissue round her nose and mouth.

Her condition is known as mucocutaneous leishmaniasis, or espundia. It’s the result of a combined assault from three different parasites, separated by billions of years of evolution and united in their disfigurement of this woman’s face.

The first partner is a sandfly. Through its bite, this blood-sucking insect spreads the ringleader of the infectious trio – a single-celled protozoan called Leishmania guyanensis (which gives the disease its name). Once inside the skin, Leishmania takes down