A New Type of Cardiac Parasite

Abstract

A THOROUGH investigation of the ultramicroscopic structure of the frog's heart performed on animals suffering from red-leg disease led to the discovery of very small parasites in the blood-stream and also in the cardiac tissue of two such animals. They accumulated mainly in the sub-endocardial space, that is, the space between the ultra-thin layer of spreading endocardial cells and the sarcolem of muscle fibres. In this space, as previously shown, individual cells, collagen fibres and nerve axons are usually found. The parasites found there in great amounts are a hitherto unknown type of protozoa. The biggest individual specimen found to date measures about 10µ There are mainly three forms: (1) a pyriform, the biggest of these specimens measured 3µ, having one cilium on its tip; (2) a spindle- or sausage-shaped appearance, having a size of 2–5µ and one cilium on each end; (3) a bizarre type of amœboidal appearance, the biggest of these being up to 10µ in size. They have cilia in irregular distribution stemming from the body.