Tuberculosis: Return of the White Plague. Medical and Laboratory Strategies for EP Projects

摘要

Along with HIV/AIDS and malaria, tuberculosis isrnincreasingly recognized is a major resurgent disease inrndeveloping countries. In locations that have substantial levelsrnof HIV/AIDS (greater than 5% prevalence), tuberculosis is arnsignificant source of difficult to diagnosis co-morbidity.rnTraditional diagnostic methods such as chest x-ray have poorrnsensitivity and specificity. Consequently the predictive valuernof the chest x-ray is quite poor. This problem has beenrnaccentuated by HIV/AIDS since disseminated TB is morerncommon in the presence of full-blown AIDS and is frequentlyrnchest x-ray negative. The traditional diagnostic mainstay forrnacid-fast bacilli (AFB) is bright field microscopy of Ziehl-rnNeelsen (ZN) sputum. The ZN method is less sensitive andrnslower than the use of fluorescence microscopy (FM),rnparticularly when bacilli counts are less than 10 per 100 fields.rnThe yield in collected sputum samples can be further enhancedrnby pre-staining sample separation and centrifugation. All ofrnthese techniques require the presence of an appropriatelyrntrained laboratory technician but are not dependent on morernsophisticated culture techniques.rnRecently, a series of amplified mycobacterium tests havernbeen developed and introduced. These tests, particularly, thernMycodot ? test are simple, rapid and conducive to remoternfield operations. However, the sensitivity, specificity, andrnpredictive value of the amplified test methodology has beenrnchallenged in a number of recent papers, particularly involvingrnSub-Saharan populations with high HIV/AIDS prevalencernrates. The data surrounding the use of amplified testrnmethodology will be reviewed; in addition, a proposed costeffectivernlaboratory-testing algorithm will be discussed.