Pfeifferinella SP. [pfeifferinellidae, apicomplexan] infecting the fresh water snail pirenella conica light and electron microscope studies

Coccidian oocysts were proved to be found in 70 of 100 collected Pirenella conica snails, with a natural infection of 70%. It was observed that, Pfeifferinella sp. was transferred between hepatopancreas and small intestine of snail. The prepatent period of Pfeifferinella sp. infecting P. conica snails ranged from 14-18 days and the patent period was reached 50 days [P.L]- Mer-ogony stages were the early stages observed in this study. These stages were observed in the hepatopancreas and in a large clear parasiteophorous vacuole [PV]. In snails killed 4 days P.I. immature meronts were measured 12x10 microm containing 8 nuclei. Meanwhile, mature meronts with about 6 differentiated merozoites were detected as early as 6 days P.I., and measured 3.1xl.4jim. The earliest gametogonic stages were seen in the intestine of Pirenella conica snails killed 12 days P.L Microgamonts contained about 4 nuclei and measured 79x6.7microm. The mac-rogamonts measured 7.3x5.6|

Lambs Infected with UV-Attenuated Sporocysts of Sarcocystis ovicanis Produced Abnormal Sarcocysts and Induced Protective Immunity against a Challenge Infection

The present study surveyed the prevalence of natural infection of the sheep esphagus muscle with sarcocysts of Sarcocystis ovicanis and examined induction of protective immunity using UV-attenuated sporocysts. The overall prevalence of natural infection of the sheep was 95%. Infectivity of the collected sarcocysts was confirmed by shedding of sporulated oocysts after feeding infected esophageal tissues to dogs. To induce protective immunity, lambs were immunized 3 times (once a week) with 1.5 x 10(4) sporocysts exposed to UV-light for 30 min (UV-30 group) or 60 (UV-60 group) min and then challenged with 1.5 x 10(4) normal sporocysts at the 3rd week post the 1st vaccination. These lambs showed high survival and less clinical signs of sarcocystosis than normal infected lambs. The attenuated sporocysts produced abnormal cysts; small in size and detached from the muscle fiber. These abnormalities were more obvious in UV-60 group than UV-30 group. Also, the IFN-gamma level and lymphocyte percentage were increased while the total leukocyte count was decreased in the UV-60 group compared with other groups. The high level of IFN-gamma may be an evidence for the induction of Th1 responses which may have protective effect against a challenge infection.