Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.7/54
Título: The reinfection threshold promotes variability in tuberculosis epidemiology and vaccine efficacy
Autor: Gomes, M. G. M.
Franco, A. O.
Gomes, M. C.
Medley, G. F.
Orientador: Proceedings. Biological sciences, R.S.
Palavras-chave: Models, Biological
ycobacterium Infections/immunology
Disease Transmission, Infectious/prevention & control
Tuberculosis/epidemiology
Tuberculosis/immunology
Tuberculosis/transmission
Data: Mar-2004
Citação: Gomes, M.G., Franco, A.O., Gomes, M.C., Medley, G.F.(2004)."The reinfection threshold promotes variability in tuberculosis epidemiology and vaccine efficacy".Proceedings. Biological sciences, R.S. 271(1539):617-23
Resumo: Population patterns of infection are determined largely by susceptibility to infection. Infection and vaccination induce an immune response that, typically, reduces susceptibility to subsequent infections. With a general epidemic model, we detect a 'reinfection threshold', above which reinfection is the principal type of transmission and, consequently, infection levels are much higher and vaccination fails. The model is further developed to address human tuberculosis (TB) and the impact of vaccination. The bacille Calmette-Guérin (BCG) is the only vaccine in current use against TB, and there is no consensus about its usefulness. Estimates of protection range from 0 to 80%, and this variability is aggravated by an association between low vaccine efficacy and high prevalence of the disease. We propose an explanation based on three postulates: (i) the potential for transmission varies between populations, owing to differences in socio-economic and environmental factors; (ii) exposure to mycobacteria induces an immune response that is partially protective against reinfection; and (iii) this protection is not significantly improved by BCG vaccination. These postulates combine to reproduce the observed trends, and this is attributed to a reinfection threshold intrinsic to the transmission dynamics. Finally, we demonstrate how reinfection thresholds can be manipulated by vaccination programmes, suggesting that they have a potentially powerful role in global control
URI: http://hdl.handle.net/10400.7/54
http://dx.doi.org/10.1098/rspb.2003.2606
ISSN: 0962-8452
Versão do Editor: http://dx.doi.org/10.1098/rspb.2003.2606
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