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Tropheryma whippelii DNA in saliva of patients without Whipple's disease.

Tropheryma whippelii is the causative agent of Whipple's disease, a difficult to diagnose systemic illness. Amplification of part of its 16S ribosomal RNA gene(s) has become a standard diagnostic method because of increased sensitivity as compared to classical histopathological analysis. Recently, we demonstrated the presence of T. whippelii DNA by PCR in duodenal biopsies and/or gastric juice of a considerable fraction of individuals without clinical signs of Whipple's disease. In this follow-up study, saliva and dental plaques of the same patients were screened for the presence of T. whippelii DNA. Six out of the 14 previously PCR-positive persons but none of the 17 controls had T. whippelii DNA in their saliva. Our results suggest that Whipple bacteria are ubiquitous environmental or commensal organisms causing Whipple's disease only in a particular subset of individuals, possibly those with an as yet uncharacterized immunological defect.

Actinobacteria↗

PubMedDate not supplied

Reliability block diagrams to model disease management.

BACKGROUND AND OBJECTIVES: Studies of diagnostic or therapeutic procedures in the management of any given disease tend to focus on one particular aspect of the disease and ignore the interaction between the multitude of factors that determine its final outcome. The present article introduces a mathematical model that accounts for the joint contribution of various medical and non-medical components to the overall disease outcome. METHODS: A reliability block diagram is used to model patient compliance, endoscopic screening, and surgical therapy for dysplasia in Barrett's esophagus. RESULTS: The overall probability of a patient with a Barrett's esophagus to comply with a screening program, be correctly diagnosed with dysplasia, and undergo successful therapy is 37%. The reduction in the overall success rate, despite the fact that the majority of components are assumed to function with reliability rates of 80% or more, is a reflection of the multitude of serial subsystems involved in disease management. Each serial component influences the overall success rate in a linear fashion. Building multiple parallel pathways into the screening program raises its overall success rate to 91%. Parallel arrangements render systems less sensitive to diagnostic or therapeutic failures. CONCLUSIONS: A reliability block diagram provides the means to model the contributions of many heterogeneous factors to disease outcome. Since no medical system functions perfectly, redundancy provided by parallel subsystems assures a greater overall reliability.

Barrett Esophagus↗