Human Rabies Post-Exposure Prophylaxis and Animal Rabies in Ontario, Canada, 2001-2012.

In Ontario, Canada, the implementation of an annual rabies control programme in wildlife that began in 1989 resulted in a marked, steady decrease in the number of animal rabies cases. The number of animal rabies cases decreased from 1870 in 1989 to 183 in 2000 (Nunan et al., 2002 Emerg Infect Dis 8, 214). In our study period, the number of animal rabies cases continued to decrease from 210 in 2001 to 28 in 2012. The marked decrease in animal rabies cases since 1989 has resulted in a decrease in the risk of human infection. A concomitant decrease in the number of rabies post-exposure prophylaxis (RPEP) administered was anticipated but failed to occur. The mean rate of RPEP, 13.9 RPEP administered per 100,000 persons, from 2001-2012 was approximately the same as the rate in the 1990 s. Two possible reasons that the rate of RPEP administration has not decreased include strict adherence to RPEP recommendations and administration of RPEP when it is not recommended. A reduction in the number of RPEP administered, consistent with the decrease in the animal rabies cases, would provide some financial savings for the government. Ideally, an increased use of the risk assessment approach in keeping with recent guidelines, rather than adhering to previous prescriptive recommendations for RPEP administration, coupled with a continuing low incidence of animal rabies cases will result in decreased, and yet appropriate, use of RPEP. Consideration should be given to identify how guidelines could be revised to more effectively target high-risk exposures and reduce the administration of RPEP for instances in which the risk of rabies virus exposure is exceedingly low.

A comparative study of myosins and prekeratin in epithelial cells of methacarn-fixed tissues.

Around the turn of the century, tonofibrils and contractile myofibrils were observed within the same cells. These findings have been largely forgotten. To clarify the topical relations of these proteins in epithelial cells, duplicate sections of methacarn-fixed human and canine tissues were treated with the tannic acid-phosphomolybdic acid (TP)-Levanol Fast Cyanine 5RN reaction for myosins and the PAP technic for prekeratin, respectively. In bronchi, lingual and sweat glands, liver and pancreas, myosin was confined to the terminal bar-terminal web system, including pericanalicular layers. Prekeratin occurred throughout the epithelium of bronchi and ducts; secretory cells showed little or no reaction. Observations on myosin in kidney confirmed data by Harper et al. (1970). The PAP technic colored transitional epithelium and collecting tubules intensely; convoluted tubules did not react. Staining of segments of Henle's loops varied from case to case. Both reactions colored thymic epithelial cells. In myoid cells of Hassall's corpuscles myosin was gradually replaced by prekeratin and keratin. Basal cells of epididymis reacted strongly with the PAP technic, but did not contain myosin. Prekeratin is apparently identical with epidermin, whose composition and structure were well known in the 1950's. Epidermin undergoes chemical changes as cells move from the stratum basale to the stratum corneum. According to DAKO, the antibodies used in this study were prepared with prekeratin extracted from stratum corneum. Data in the literature and observations in this investigation indicate that some samples of antibodies do not react with all tonofilaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Histogenesis of vascular tumors in the Proteus syndrome.

Proteus syndrome (PS) is a congenital disorder manifesting with severe deformities, the salient features being gigantism and vascular tumors. The disorder is poorly understood, and there has been much discrepancy in the terminology regarding the vascular tumors in PS. The purpose of this study was to elucidate the histogenesis of these tumors by correlating microscopic observations with immunohistologic information. The value of immunoperoxidase studies in the pathologic evaluation of PS was also assessed. Fourteen formalin-fixed, paraffin-embedded tissue specimens obtained from vascular tumors of six children with PS were stained with Ulex europaeus agglutinin I (UEA-I) lectin and the following immunohistochemical reagents: anti-factor VIII-related antigen (FVIII-RAg) and anti-CD34. The tumors showed varied proportions of vascular, lipomatous, and fibrous tissue components consistent with vascular hamartomas. The predominant vascular channels of the tumors were morphologically consistent with lymphatic vessels. Immunostaining of the endothelium of these vessels was most consistently positive with UEA-I lectin. Although a color reaction product was present in small vessels and some larger blood vessels, anti-CD34 immunostaining spared the lumens of lymphatic channels. In addition, a striking population of dendritic spindle cells was noted with the anti-CD34 but was unnoticed with the other reagents. We concluded that the vascular tumors of PS are primarily lymphatic hamartomas. The spindle cells noted with anti-CD34 immunostaining may relate to angiogenesis and need further delineation.