Lábrea fever, also known as Lábrea's black fever and Lábrea hepatitis, is a lethal tropical viral infection discovered in the 1950s in the city of Lábrea, in the Brazilian Amazon basin, where it occurs mostly in the area south of the Amazon River, in the states of Acre, Amazonas and Rondônia
A remix version of the song entitled "Labrea, Circle of Equals (Trial of Grievance)" (aka "Arkam Bridge") was used later in Civilization II in the Hoover Dam Wonder video.