The development of Theileria sergenti, Babesia ovata, and Babesia gibsoni in their vertebrate hosts, and in the tick vector, Haemaphysalis longicornis is investigated. Three forms of T. sergenti are noted in host erythrocytes, the bacillus-like, coccus-like and rod-like forms. In the tick vector, T. sergenti goes through gametogony (ring, and round forms, microgamete, macrogamete and zygotes) in the gut, and sporogony (primary, secondary and tertiary sporoblasts, and sporozoites) in the salivary glands. Morphologically, merozoites of B. ovata are classified into four types: single pyriform, budding form, paired pyriform and crisis form. In tick host infected with B. ovata, two growth stages can be observed, gametogony (ring, spherical, fission, bizarre and elongate forms, microgamete and zygote) in the gut, and sporogony (sporont and sporozoites) in the salivary glands. In its tick vector, B. gibsoni undergoes gametogony (ring, spherical, fission, bizarre, elongate forms, microgamete, and zygote) in the gut.
From 1981 to 1990, 93 Thoroughbred in Japan were examined for Sarcocystis cysts using light, scanning and transmission electron microscopy. Tryptic digestion of muscle tissues revealed six infected horses. Sarcocystis bradyzoites were found in the myocardium, masseter and diaphragm muscles. Cysts were elliptical, spindle or mulberry shaped, measuring 77.7 - 222.0 µm x 48.1 - 111.0 µm. Cyst walls were 1.0 - 0.6 µm thick and have a smooth surface in HE - stained sections. Bradyzoites ranged from 12.0 – 16.6 µm x 3.0 – 5.3 µm. The morphology of cysts revealed many similarities with Sarcocystis equicanis. No pathological changes were observed in infected muscle fibers.
Toxoplasma gondii causes abortion and perinatal mortality in goats (Dubey et al. 1981; McSporran et al. 1985; Nurse and Lenghaus 1986), and in sheep (Hartley and Marshall 1957; Beverley and Watson 1961; Plant et al. 1974; Dubey and Schmitz 1981). The higher serologic response to natural T. gondii infection in sheep compared to cattle has been reported (Munday and Corbould 1979). An attempt was thus carried out to compare the serologic status of sheep and goats which were reared together with infected flocks in Bangladesh.