Weight of the Spleen, Adrenals and Gonads during a Chronic Trypanosoma brucei gambiense Infection of Laboratory-reared Microtus montanus

Abstract

Splenomegaly occurs when male Microtus montanus are infected with Trypanosoma brucei gambiense. In addition, there is a statistically significant increase in adrenal weights and a decrease in the size of the gonads. The importance of the spleen in immunity to a trypanosome infection was documented by showing that splenectomy leads to a greatly decreased survival time. Other forms of stress can influence spleen size but not to the same degree as a trypanosome infection. The relationship between the size of the spleen and adrenals is discussed and it is suggested that parasite stress could be distinguished from other forms of stress in natural populations of Microtus. Large adrenalssmall spleen could mean nonparasite stress, whereas large adrenals-large spleen could be caused by parasite stress. The reduced gonadal weight and increased spleen weight are also discussed in relation to reproductive potential and population density.