Pathology and Pathogenesis of Chagas Heart Disease

Chagas heart disease is an inflammatory cardiomyopathy that develops in approximately one-third of people infected with the protozoan parasite Trypanosoma cruzi. One way T. cruzi is transmitted to people is through contact with infected kissing bugs, which are found in much of the Western Hemisphere, including in vast areas of the United States. The epidemiology of T. cruzi and Chagas heart disease and the varied mechanisms leading to myocyte destruction, mononuclear cell infiltration, fibrosis, and edema in the heart have been extensively studied by hundreds of scientists for more than 100 years. Despite this wealth of knowledge, it is still impossible to predict what will happen in an individual infected with T. cruzi because of the tremendous variability in clonal parasite virulence and human susceptibility to infection and the lack of definitive molecular predictors of outcome from either side of the host–parasite equation. Further, while several distinct mechanisms of pathogenesis have been studied in isolation, it is certain that multiple coincident mechanisms combine to determine the ultimate outcome. For these reasons, Chagas disease is best considered a collection of related but distinct illnesses. This review highlights the pathology and pathogenesis of the most common adverse sequela of T. cruzi infection—Chagas heart disease—and concludes with a discussion of key unanswered questions and a view to the future.

Bacterial infective arthritis of the coxofemoral joint in dogs with hip dysplasia

SummaryThe objective of this study was to describe seven cases of unilateral bacterial infective coxarthritis from a total of 19 cases of bacterial infective arthritis (BIA), presenting over a two year period. We recorded the history, clinical signs, diagnostic process, treatment and clinical outcome in these cases. The data were obtained from medical records, review of the radiographs, and telephone follow-up with the owners. All of the dogs in this study had severe chronic osteoarthritis secondary to hip dysplasia, which caused periodic hind limb lameness. They were all admitted with severe acute hind-limb lameness. Pelvic radiographs were performed under general anaesthesia shortly after presentation, followed immediately by arthrocentesis of the affected joint. The synovial fluid was evaluated microscopically by direct smear and a sample was sent for culture and sensitivity. An attempt was not made to drain or lavage the affected joint during the course of treatment. The initial choice of antibiotics was empiric and subsequently modified, as required, based on the sensitivity results. Four of the dogs showed a rapid return to weight-bearing after the initiation of antibiotic treatment, and all of the patients returned to their pre-BIA level of function. Neither recurrent infections nor any adverse sequela requiring further intervention were reported by the owners on telephone follow-up.

Stereotactic radiotherapy for the treatment of lymphocytic hypophysitis

✓ Lymphocytic hypophysitis is a rare inflammatory disorder of the pituitary gland. Standard therapy consists of transsphenoidal resection or oral administration of corticosteroid medications. Two patients with symptomatic lymphocytic hypophysitis, which recurred after standard therapy, were treated with low-dose stereotactic radiotherapy. On imaging studies both lesions demonstrated a response to radiation and each patient experienced relief of symptoms. There has been no adverse sequela of the radiation treatment. The authors conclude that stereotactic radiotherapy represents an effective, noninvasive treatment option for patients with lymphocytic hypophysitis, particularly if the disease is recurrent after surgery or resistant to corticosteroid medications.