 A retro-like virus infection was suspected as the causative agent of IBD, but identification of highly divergent arenavirus sequences from boa constrictors with IBD suggested arenaviruses to be the etiological agent of IBD.Cell culture isolation of several arenaviruses from boid snakes with IBD further solidified, but did not yet confirm, the etiological relationship between IBD and arenaviruses.In python species, the disease presents as a profound, highly severe neurological illness that is swiftly fatal.