Clarence R. Cole

EXPERIENCES WITH HISTOPLASMOSIS

Excerpt Histoplasmosis, which previously had been considered to be a rare and fatal disease, is not now of infrequent occurrence especially in the middle western United States. It has been shown th...

Functional and morphologic pathology of equine aortic insufficiency.

Twelve horses and 3 mules with grade II or louder prolonged diastolic murmurs were selected for functional and histopathologic study. Aortic insufficiency was demonstrated in all mules and in all except two horses on the basis of murmurs, jet lesions and/or pathologic and incompetent valve cusps. In 15 control animals lesions resulting in aortic insufficiency were not found. A thick fibrous band was present on all aortic valve cusps judged to be definitely insufficient. This band occurred at the line of valvular closure, parallel to the free edge, and allowed eversion of the peripheral portion of the cusp. Endothelial covered villi were present on the ventricular surface of those valves with band lesions. There was fibroblastic proliferation in a rich ground substance within the villi, on the surface of the ventricularis and throughout all layers of the valve. A nodular lesion microscopically similar to nonbacterial thrombotic endocarditis in man was also found on the ventricular surface. This lesion also involved all layers of the aortic leaflet with proliferation of fibrocytes and production of acid mucopolysaccharide ground substance and collagen fibers. The nodular lesions did not appear to contribute significantly to the insufficiency. Degeneration of elastic fibers and focal mineralization of the fibrosa were interpreted as senile degenerative changes.

Pulmonary Lesions in Dogs with Experimental and Naturally Occurring Toxoplasmosis

The lungs of 92 dogs with confirmed toxoplasmosis were studied. Focal areas of coagulation necrosis, adjacent to and involving small vessels and bronchioles, and exudation of fibrin were the characteristic lesions produced by T. gondii in the lungs of dogs with both experimentally induced and naturally occurring infections. The inflammatory response to the areas of necrosis was minimal. Dogs inoculated intratracheally developed more extensive pulmonary lesions with greater numbers of T. gondii than dogs inoculated by the intravenous or subcutaneous route. Toxoplasma were not demonstrated in the pulmonary lesions after the 16th day following inoculation. Distemper was a concurrent infection in 20 cases of naturally occurring toxoplasmosis. The lesions produced by the two etiologic agents were distinctly different. Based on the severity of pulmonary lesions the dogs appeared to be primarily infected with toxoplasma.

Experimental Histoplasmosis, I. Methods for Production of Histoplasmosis in Dogs.

Summary Yeast phase H. capsulatum induced acute, progressive, fatal histoplasmosis in all of 9 dogs when inoculated intratracheally, but no clinical disease in all of 7 receiving the same inoculum by stomach tube. Mycelial phase produced no clinical evidence of infection in 9 and 10 normal dogs receiving intragastric and intratracheal inoculations, respectively. Cortisone treated dogs? however, were susceptible to intratracheal but not intragastric mycelial phase inoculations. Dogs previously receiving mycelial phase were resistant to reinfection with the same phase even when given cortisone; they succumbed to challenge with intratracheal yeast phase in the absence of cortisone.

Toxoplasmosis. II. Intra-Uterine Infection in Dogs, Premature Birth and Presence of Organisms in Milk.

Summary 1. Toxoplasma of human, canine, and porcine origin was pathogenic for pregnant bitches and caused abortion or premature parturition. The organism was isolated from 23 of 28 pups born of 5 bitches. 2. In utero transmission of toxoplasmosis was demonstrated by isolation of toxoplasma from each of 8 pups (born of 4 bitches) which were collected aseptically and sacrificed at the time they emerged from the birth canal. Isolation of organisms from the placenta and allantoic fluid was further evidence of in utero transmission. 3. A mammary gland emulsion from one bitch and samples of milk collected aseptically from 4 lactating infected bitches each revealed toxoplasma.

Experimental histoplasmosis in large domestic animals.

Summary Intratracheal inoculation of yeast phase H. capsulatum produced nonfatal infection in horses, cattle, sheep and swine as determined by clinical response, development of positive skin tests, production of antibodies, or histopathologic changes. Intravenous inoculation caused fatal infection in a horse. The authors are indebted to Joann Sparks for technical assistance.

Staining Rickettsiae in Sections of Formalin-Fixed Tissue; a 12-Minute Wright-Buffer Sequence

Rhesus monkey tissues obtained at autopsy were fixed in neutral phosphate-buffered formalin, embedded in paraffin, and sectioned 3-5 μ thick. Sections were stained with Wrights stock stain for 6 min and differentiated in Wrights stock buffer for 6 min and mounted as usual. The rickettsial cytoplasm stained reddish pink; the nucleus, blue. This method was much simpler than that of Wolbach although the results obtained were nearly identical.