Hammondia hammondi: A new coccidium of cats producing cysts in muscle of other mammals.

Predominant muscle parasitism, and an obligatory two-host cycle (cat-mouse-cat), distinguishes an otherwise similar organism from Toxoplasma. The presence of multiplicative stages in the cat gut separate it from Sarcocystis. Antibody that cross reacts with Toxoplasma antigen is developed in mice and other experimental intermediary hosts, but not in cats, the final host. Recognition of the two-host cycle is essential for the experimental isolation and transmission of the parasite, and for prevention of the infection.