Sheep Experimentally Infected with Sarcocystis from Dogs. I. Disease in Young Lambs

Abstract

Eight Polled Dorset lambs were orally inoculated with Sarcocystis ovicanis sporocysts. Two lambs that received 100,000 or 200,000 sporocysts became clinically ill, recovered, and were killed 67 and 88 days after inoculation (DAI). Numerous intramuscular cysts were found in their skeletal and cardiac muscles. Three lambs received 100,000 sporocysts, three lambs received 1 million sporocysts, and three lambs received no sporocysts. After an acute clinical illness characterized by anemia, inappetence, weight loss, fever, and reduced serum protein, all lambs that received 100,000 sporocysts died 27 to 29 DAI and all that received 1 million sporocysts died 24 or 25 DAI. Hemorrhage involving the striated muscle and visceral organs was the most apparent gross lesion. The heart appeared most severely affected. Schizonts were found in vascular endothelial cells of all six inoculated lambs. Uninoculated lambs remained healthy, and neither lesions nor parasites were found in any tissues. Dogs fed tissues containing S. ovicanis cysts produced sporocytes 11 to 37 days after feeding; cats fed similar stages produced no sporocysts. Dogs fed tissues containing schizonts produced no sporocysts.

Use of the Muscle Digestion Method and Indirect Immunofluorescence Reaction in the Diagnosis of Sarcocystosis in Sheep

“…sporocysts. The first cysts can be observed 3 months after infection at the earliest (Leek et al 1977;O'Toole et al 1986). …”

Sarcocystis spp. in Human Infections

“…At approximately 4 weeks after ingestion of sporocysts, a subsequent asexual generation matures in vascular endothelial cells with an accompanying acute inflammatory reaction. This reaction is characterized by massive perivascular infiltration of mononuclear cells and multiorgan petechial hemorrhage associated with weakness, fever, abortion in pregnant animals, and sometimes death (22,23,31,40). The severity of infection is dependent on the number of sporocysts ingested.…”

Aborto ovino associado com infecção por Sarcocystis sp

“…O mecanismo pelo qual Sarcocystis sp. induz o aborto ainda é desconhecido (Mackie et al 1992) e a presença do protozoário e de lesões histológicas raramente é observada nos tecidos fetais (Corner et al 1963, Stalheim et al 1976, Barnett et al 1977, Leek & Fayer 1978. Além do aborto, outros sinais clínicos como febre, anemia, anorexia, perda de peso, problemas de coagulação sanguí-nea e fraqueza são também descritos em animais infectados .…”