Experimentally induced sarcocystis infection in calves: pathology

Calves fed sporocysts of Sarcocystis isolated from the feces of dogs and coyotes became anorectic, lost weight, and became anemic and prostrate, and died. The most severe pathologic changes occurred between 26 and 33 days after infection; schizonts were found throughout the body. Schizonts were not found after this time. Sarcocytis cysts were in skeletal and cardiac muscles between 33 and 54 days. Necropsy revealed lymphadenopathy, paleness of the mucous membranes and visceral organs, ascites, hydrothorax, hydropericardium, and serous atrophy of fat. Ecchymotic or petechial hemorrhage was in heart, brain, serosa of the alimentary tract, and urinary bladder. Microscopic changes observed in nearly all calves consisted of hemorrhage, mononuclear cell (primarily lymphocytic) infiltration and edema in heart, brain, liver, lung, kidney, and striated muscle. Necrotizing myocarditis with dystrophic calcification of the striated muscle and fat, as well as nonsuppurative inflammation of meninges and glial nodules in the brain, was observed in several calves.

Prevalence of Dirofilaria immitis in a stray dog population in western New York

In a survey in 1973 undertaken to determine the prevalence of Dirofilaria immitis in 100 dogs from a public pound in western New York, 2 dogs were found to be positive. Microfilariae of Dipetalonema sp were not present. Hearts and pulmonary blood vessels were dissected for adult worms, and blood samples were examined for microfilariae, using a modified Knott technique. Although adult heartworms and microfilariae have been recovered from wild foxes, coyotes, and wolves in New York, this is the first report of heartworm in domesticated dogs in the state.

Deep vascular schizogony in Plasmodium fragile: organ distribution and ultrastructure of erythrocytes adherent to vascular endothelium

Erythrocytes infected with Plasmodium fragile, like those infected with P. falciparum and P. coatneyi, adhere to vessels in heart, adipose tissue and, to a lesser ex00 nm knob protrusions on the plasma membrane of infected erythrocytes. The close apposition between knobs and endothelium (1 nm or less) excludes macromolecules such as fibrinogen or antibodies as the adhesive force. The components on the membrane responsible for adhesion at the knobs remain unknown.

Studies on the host specificity of the eyefluke, Diplostomum spathaceum, in brown and rainbow trout

Trout collected from the Hanningfield Trout Farm in Essex, England, were found to be infected with Diplostomum spathaceum. Yearling rainbow trout were blinded with heavy infections of eyefluke, whereas brown trout of the same age carried one-tenth the number of flukes and were clear eyed. Both species were reared under identical conditions, in parallel rearing channels which received water from a common source. Samples showed that young fish exhibited a similar differential in their infestations, and that rainbow trout did not appear to be age-resistant. Laboratory infections produced by exposure of fish to suspensions of cercariae and injection of cercariae into the body cavity reflected the field results, indicating that ecological factors were not involved. Recovery of cercariae from host tissues, and histological observations of similar numbers entering both hosts, indicated that cercariae were able to survive penetration. Excised eye preparations were equally susceptible to infection. Two cm fry of both species were shown to be highly susceptible. Migration in brown trout took 3 h longer than in rainbow trout of the same size, many cercariae being found in the heart during this time. Two mechanisms of insusceptibility were suggested: (1) a greater impenetrability of brown trout tissues; (2) a disorientation of migrating cercariae in brown trout.