Morphological and taxonomic studies on mammalian trypanosomes

Abstract

An account is given of two aberrant strains of Trypanosoma evansi recovered from Sudanese camels.One of these—like the four other ones described in a previous paper—was totally akinetoplastic (= akinetonucleate) and has been kept under observation for eighteen months in the course of which the aberrant condition remained unchanged.The second strain was characterized by a wide fluctuation in the proportion of akinetoplastic forms which ranged from zero to over 70% at different periods of observation.The bearing of this fluctuation upon the production of akinetoplastic strains is discussed and it is concluded that these probably arise in nature either indirectly, through the inoculation by the insect vector of new hosts with trypanosomes lacking the kinetoplast, or directly, by the strain becoming totally akinetoplastic within the same host.From an analysis of the fluctuating strain it would appear that the variation in the proportion of akinetoplastic trypanosomes depends upon the following factors: (1) irregular division (without bipartition of the kinetoplast), which is the most important factor; (2) rate of reproduction of normal and aberrant individuals; (3) mortality rate of the different types of dividing and non-dividing forms.The primary cause of the disappearance of the kinetoplast could not be ascertained.