Development of Sarcocystis suicanis Erber, 1977 in the pig.

Twenty-eight weanling pigs inoculated with sporocysts from an isolate of Sarcocystis suicanis from Georgia were examined at intervals ranging from 2 to 90 days postinoculation (DPI). Merogony was first observed histologically within the heart muscle 12 DPI and within 23 of 35 tissues examined 13 DPI. Most infected cells were "floating" in extravascular spaces and were near intact endothelial cells. In some cases, the infected cell clearly was an endothelial cell comprising a portion of the capillary wall. Immature sarcocysts containing metrocytes were observed in striated muscle 27 DPI, and bradyzoites were detected by digestion techniques 52 DPI. Sarcocysts matured between 27 and 80 DPI, after which thickness of the cyst wall and morphology of bradyzoites changed little. Dissolution of sarcocysts was detected as early as 38 DPI and was accompanied by ingress of plasma cells, lymphocytes, and occasionally, eosinophils. Based on information presented herein, feeder pigs reared on pasture may become infected, and infections mature well within the 100-day period usually considered necessary for production of marketable swine.

Experimental Sarcocystis suicanis infections: disease in growing pigs.

Four groups of 6 pigs each were given 5 x 10(5) to 3 x 10(6) sporocysts of a Georgia isolate of Sarcocystis suicanis. Only the 6 pigs given 3 x 10(6) sporocysts became acutely ill at postinoculation days (PID) 12 to 15, and 3 of the 6 diet at PIG 14 or 15. Clinical signs included purpura of the skin of the ear, snout, and buttocks and dyspnea, muscle tremors, and severe locomotor difficulties. Clinical abnormalities were accompanied by laboratory findings of pyrexia, severe anemia, leukopenia, thrombocytopenia, megathrombocytosis, prolonged prothrombin time and activated partial thromboplastin time, and hypofibrinogenemia. Seemingly, excessive intravascular coagulation may be involved in the pathogenesis of this disease in swine. Pigs given 5 x 10(5) to 1 x 10(6) sporocysts did not exhibit clinical signs; however, leukopenia and thrombocytopenia were demonstrated in the pigs at all dosage levels. Growth rates were impaired in surviving pigs. Second-generation schizonts containing merozoites were found in vascular endothelium of pigs dying on PID 14 or 15. Nonsuppurative myocarditis and hepatitis were present. Numerous developing cysts were in the musculature of pigs enthanatized on PIG 35 to 52. Cyst dissolution and resorption occurred concomitantly, indicating that swine may be able to clear the infection.

Studies of endoparasites of the mourning dove (Zenaida macroura) in the southeast United States.

From September, 1973, through November, 1974, 255 mourning doves (Zenaida macroura) were collected in the southeastern United States and examined for endoparasites. Thirteen species of endoparasites were found and included six species of protozoans, one trematode, two cestodes, and four nematodes. New host records included Sarcocystis sp., Echinostoma revolutum, Hymenolepis sp., Aproctella stoddardi, Ascaridia columbae, and Dispharynx nasuta.

Prevalence and distribution of Sarcocystis sp among wild swine of southeastern United States.

Digestive techniques revealed Sarcocystis sp infection in 62 of 192 (32%) wild swine collected in Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia. Sarcosporidia were not detected in wild swine of Florida and were rarely found in the lower coastal plains of Georgia, Mississippi, and South Carolina. Swine from mountainous terrain in North Carolina, Tennessee, and West Virginia and bottomland floodplain regions of Alabama, Arkansas, and Louisiana were most frequently infected. Infections by sarcocystis sp may have been spread via swine relocated from mountainous regions to some other locales. Upon ingestion of infected pork from wild swine of Tennessee and West Virginia, dogs, but not cats, shed sporocysts morphometrically identical to Sarcocystis suicanis.