Klossiella equi Baumann, 1946 (Sporozoa: Eucoccidia: Adeleina) from Equids

Abstract

Kidneys from 5 of 40 ponies (Equus caballus) and from 3 of 14 burrows (Equus asinus) were found infected with Klossiella equi. In addition to previously reported sporogonous stages in epithelial cells of Henle's loop, schizogonic stages in endothelial cells of Bowman's capsule and epithelial cells of the proximal convoluted tubules are described. The association of macroand microgametocytes in syzygy is discounted, and a microgametocyte with 8 to 10 microgametes is characterized. Microgametes in the process of migrating to macrogametes are reported. A life cycle for this parasite is proposed. Baumann (1946) first described Klossiella equi from the kidney of a horse in Hungary. He suggested that (1) macrogametes and microgametes develop in syzygy with the formation of four microgametes and (2) after syngamy, the zygote grows and produces, by multiple nuclear fission followed by budding from a large central residual mass, a large number of sporoblasts that develop into sporocysts. Akcay and Urman (1954) found the parasite in kidneys of 72 donkeys in Turkey incidental to experimental work on equine infectious anemia. The species was also described from a burro (Equus asinus) in the United States by Seibold and Thorson (1955a). These workers observed four distinct developmental stages in kidney tubule cells and proposed the following descriptive terms: (1) uninuclear, (2) multinuclear, (3) budding, and (4) thin-walled sac with sporocysts enclosed. In the fourth stage, they counted as many as 12 sporozoites in the sporocysts. They later (1955b) concluded that their parasite was identical to Baumann's K. equi after examining his slides. Newberne, Robinson, and Bowen (1958) found K. equi in the kidney of a zebra from Africa that died in a Florida zoo. Four different sporogonic stages were found in the tubule cells of the medulla. One to four small eosinophilic masses, which were present within the vacuoles of the uninuclear form, were thought to be the microgametocytes suggested by Baumann (1946). Sasmore (1959) found four morphological stages of the parasite Received for publication 28 September 1971. 589 in 28 burros (E. asinus) and one horse (E. caballus) in Tennessee. He proposed the following terms: (1) trophozoite, (2) preschizont, (3) schizont, and (4) sporocyst. He also speculated upon a possible interrelationship of K. equi with skin and intestinal globidial cysts. Hartman (1961) also found K. equi in eight burros. He followed the terminology proposed by Seibold and Thorson (1955a), described the sporogonic phases of the life cycle, and mentioned that the small bodies in the uninuclear phase may be macroand microgametocytes. Klossiella equi has been found in eight equids used in piroplasmosis research during the past 3 years at this laboratory. This report describes the endogenous stages that were found and presents our version of the life cycle of the parasite. MATERIALS AND METHODS Kidney tissues, taken from ponies (Equus caballus) and burros (Equus asinus) that died or were killed during studies of piroplasmosis, were either quick-frozen and sectioned in a cryostat or fixed with Helly's fluid, infiltrated with paraffin, and sectioned. Sections were stained with either Heidenhain's iron hematoxlyin with no counterstain (Lillie, 1965), Himes and Moriber's trichrome (Himes and Moriber, 1956), or Whipfs polychrome stain (Vetterling and Thompson, in press). Sections were examined at either 400 or 800 X with light-field or dark-field fluorescent micros-