Complex sentence: Visceral leishmaniasis (VL), also known as kala-azar and black fever, is the most severe form of leishmaniasis, a disease caused by parasites of the "Leishmania" genus.
Split into simpler sentences: Visceral leishmaniasis (VL), also known as kala-azar and black fever, is the most severe form of leishmaniasis. Leishmaniasis is a disease caused by parasites of the "Leishmania" genus.