Molecular answers to tuberculous questions

Autor: E G Hoal-van Helden, Paul D. van Helden
Rok vydání: 2000
Předmět:
Zdroj: The Lancet. 356:S61
ISSN: 0140-6736
DOI: 10.1016/s0140-6736(00)92047-6
Popis: Diagnosis and treatment P of individual patients with tuberculosis may not differ substantially between more-developed and less-developed countries. However, the differences in case-load, resources, and management result in a huge divide between the two. Tuberculosis may be regarded as a two-component disease: recent transmission, implying progression to disease after infection; and reactivation. In cases of reactivation, progression to disease may occur many years after infection. In the moredeveloped countries, most cases of tuberculosis are reactivation disease in older people and disease in immigrants. By contrast, the higher annual risk of infection and paediatric case-load implies substantial continuing transmission in less-developed countries. Decades of observation have lead to the formulation of ideas about tuberculosis, such as: multiple household cases are the result of household transmission; repeat episodes of disease are the result of relapse; and drug resistance arises largely through the acquisition of resistance due to treatment failure. In high-incidence communities, these beliefs may not necessarily be true. For adults, the use of Ziehl-Neelsen staining is fairly effective in more-advanced pulmonary disease. However, it is not straightforward in non-pulmonary and paediatric tuberculosis, at early presentation (low bacterial load), and where HIV is present. In Africa particularly, this will be important, because it has been estimated that smearnegative cases can transmit tuberculosis at a rate roughly quarter that of smear-positive cases. Although the use of other diagnostic technology and case-finding will initially be more costly, what should be considered is the longterm cost of missed cases, which perpetuate the epidemic. Molecular epidemiology enables us to ask various
Databáze: OpenAIRE
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