Hammondia hammondi gen. nov., sp.nov., from domestic cats, a new coccidian related to Toxoplasma and Sarcocystis

Abstract

Hammondia hammondi gen.nov.,sp.nov (Eimeriorina:Sarcocystidae) is described as an obligate heteroxenous protozoon of domestic cats (final host) and laboratory mice (experimental intermediate host). Oocysts from the final host are infectious only for the intermediate host; and cysts from the intermediate host are infectious only for the final host. Intracellular cysts develop principally in striated muscle of mice that ingest oocysts, with a few cysts in the brain and perhaps elsewhere. Cysts are without septa or radial spines; bradyzoites are slender, there is no evidence of metrocytes. Cysts are not infectious for mice. After the ingestion of cysts by cats, a multiplicative cycle precedes the development of gametocytes in the epithelium of the samll intestine. Oocysts are shed unsporulated, sporogony is outside of the host, resulting in two sporocysts with four sporozoites each. Oocysts of the species average 11 x 13 mum. The prepatent period i 5s 5 to 8 days, and oocyst shedding persists for 10 to 28 days followed by immunity. Cysts in skeletal muscle measured between 100 and 340 mum in length and 40 and 95 mu-m in width. Experimental intermediate hosts are laboratory mice, rats, hamsters, guinea pigs, Peromyscus and Mastomys. Some of the intermediate hosts develop low levels of antibody and some cross-immunity against Toxoplasma; however, this has not been observed in cats.

The coccidian parasites (Protozoa, Apicomplexa) of carnivores

“…Patent Period. This was found by Frenkel and Dubey (1975) to be 10-28 days or by Dubey (1975b) Dubey (1975, 1975a) Dubey, , 1975aRommel and von Seyerl, 1976). In other words, T. hammondi has an obligate 2-host life cycle.…”

“…3 days at 20-23 C in 2% sulfuric acid solution (Frenkel and Dubey, 1975) (Dubey and Streitel, 1976b). Meronts in the skeletal muscles of mice were found by Frenkel and Dubey (1975) to be 100-340 x 40-95 /mi. They were nonseptate, had no radial spines, and contained slender merozoites only.…”

“…Hammondia hammondi Frenkel, 1974, Frenkel andIsospora hammondi (Frenkel and Dubey, 1975), Tadros and Laarman, 1976. Type Dubey, 1975, 1975a), domestic dog Canis familiaris (Dubey, 1975b), marmoset Saguinus nigricollis (Dubey and Wong, 1978). In addition, Dubey (1975, 1975a) (Frenkel and Dubey, 1975;Dubey and Streitel, 1976b). Rommel and von Seyerl (1976) found meronts only in the striated muscles.…”

“…The sporulated oocysts are subspherical to ellipsoidal, 13-14 x 10-11 (mean, 13 x 11) jum, without a micropyle, residuum, or polar granule. The sporocysts are ellipsoidal, 9-11 x 6-8 (mean, 10 x 6.5) (Frenkel and Dubey, 1975). (Rommel and von Seyerl, 1976, said that the unsporulated oocysts were 12-18 x 10-15 /im with a mean of 14 x 12 /urn.…”

“…As in T. gondii, there is a third wave of multiplication in the epithelium of the small intestine before gametogony (Frenkel and Dubey, 1975).…”