Persistent infection of Mongolian jirds with a non-pathogenic trypanosome,Trypanosoma (Herpetosoma) grosi

Abstract

Non-pathogenic trypanosomes of the subgenusHerpetosomaare normally host specific, and laboratory models includeTrypanosoma lewisiin rats andTrypanosoma musculiin mice. Two isolates ofTrypanosoma grosi, originating fromApodemus agrariusandApodemus peninsulae, grew well in Mongolian jirds,Meriones unguiculatus, after intraperitoneal inoculation of 2×105or a minimum 500 bloodstream forms. The course ofT. grosiinfection in jirds resembledT. musculiinfection in mice, rather thanT. lewisiinfection in rats. At week 2 to 3 p.i. trypanosomes disappeared from the bloodstream, and neither prednisolone treatment nor splenectomy prevented parasite elimination from the bloodstream. However, these treatments induced a marked increase in peak parasite counts. Regardless of prednisolone treatment or splenectomy, all jirds after day 21 p.i. became resistant to the reinfection. Although no trypanosomes were detected in the bloodstream of recovered jirds, dividing parasites persisted in the medullary capillaries of the kidney, likeT. musculiinfection in mice. We propose theT. grosiinfection in jirds as an additional laboratory model for the study of non-pathogenic trypanosomes.