The world’s largest outbreak of waterborne toxoplasmosis occurred in a municipality in the western Canadian province of British Columbia. When drinking water emerged as a possible source of infection during the outbreak investigation, a laboratory method was needed to attempt detection of the parasite, Toxoplasma gondii. The method developed was based on the current U.S. Environmental Protection Agency method for detection of Cryptosporidium oocysts. Collection of large-volume drinking water samples and cartridge filter processing were unchanged, although identification of Toxoplasmaoocysts in the filter retentate was carried out by using a previously described rodent model. Validation of the method developed was tested by using oocysts from a well-characterized Toxoplasmastrain.

Over 120,000 hip prostheses are implanted annually in North America. The rate of revision arthroplasty for loosened large joint prostheses is burgeoning because primary arthroplasties are now performed on younger and more physically active patients. Increasingly, pathologists are being confronted with specimens from these reoperations. The histologic descriptions of the inflammatory tissue that surrounds these loosened prostheses stress the histiocytic and foreign body giant cell reaction, the appearance of the wear debris, and the utility of stromal neutrophils in identifying infection. In fact, the morphologic range of this inflammatory reaction is wider than generally reported in the literature. To define better the histopathology of the tissue surrounding loosened large joint prostheses, 104 revision hip arthroplasty specimens (1,164 hematoxylin and eosin slides, mean 11.2 per case) were examined. Multiple intraoperative bacterial cultures were obtained in 82 cases, of which 8 were positive. Foreign body giant cells and foamy histiocytes were identified in 88 and 89% of cases, respectively. Polyethylene, methylmethacrylate, and metal debris were present in 74, 78, and 63% of cases, respectively. Elemental analysis, performed in selected cases, demonstrated the presence of chromium, cobalt, and titanium, confirming that the observed metal particles were derived from detrition of the femoral component of the implant. Extensive coagulative necrosis was displayed in 67% of the cases. A distinctive papillary fibrocartilaginous metaplasia of synovium was seen in 50% of cases. Superficial fibrinous exudates were present in 62% and active bone remodeling in 49% of cases. The reactive tissue in 8% focally resembled nodular and proliferative fasciitis. Stromal neutrophils, identified in 20% of cases, strongly correlated with positive cultures ( r = .5641, P < .0001, sensitivity = 88%, specificity = 88%). Perivascular plasma cell aggregates, present in 14% of cases, also correlated with positive cultures ( r = .3290, P = .0025, sensitivity 50%, specificity 91%). Superficial fibrin and neutrophils, scattered lymphocytes, and lymphoid aggregates were all poor and insignificant predictors of infection. This study demonstrates that the spectrum of the inflammatory reaction to loosened large joint prostheses is greater than previously appreciated. The value of stromal neutrophilia and perivascular plasma cells in identifying infection is highlighted.

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