Visceral leishmaniasis, also known as Kala Azar, is a parasitic disease responsible for 500,000 cases worldwide each year. It was first observed in 1824 in India and was caused by Leishmania donovani parasites. Dr. Nicolaes Tulp, who was immortalized in Rembrandt's painting "The Anatomy Lesson of Dr. Tulp", made several medical contributions in the 1600s and helped establish standards for pharmacists in Amsterdam. Walter Reed helped prove that yellow fever was transmitted by mosquitoes, paving the way for construction of the Panama Canal, and a medical center is named after him.