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 International Conference on Complex Systems (ICCS2007)

A Newly Identified HIV Dynamics Effect That Is A Key To HIV Control Is Reflected By Readily Observable Sequence Relationships

James Koopman
University of Michigan

Ethan Romero-Severson
Dept. of Epidemiology, University of Michigan

Jong-Hoon Kim
Dept. of Epidemiology, University of Michigan

     Full text: Not available
     Last modified: July 29, 2007

Abstract
Behavior fluctuations in the number of risky contacts, type of risk, and the population in which contacts are made are shown to have surprisingly strong effects on endemic levels of HIV infection, on the potential for any intervention to control HIV transmission, and on the relative effectiveness of different HIV control programs. These effects arise because of the high transmissibility of HIV during very early infection. The effect on endemic levels of infection is similar in nature to some contact network effects identified as affecting HIV transmission. This behavior fluctuation effect, however, is more powerful and more likely to be acting in diverse populations. The effects on control program outcomes are complex and although they are not intuitive, they are readily explainable. Strong interactions in generating these control program effects arise between degree of risk fluctuation, timing of fluctuations, contact patterns, and endemic infection levels. The same forces that generate these effects alter the shapes of infection transmission trees. Thus, information on these effects can be extracted from genetic sequences. Fortunately inferences only require distance measurements between cases and identification of whether sequences were obtained from early infection or not. Thus the difficulties in inferring phylogenetic relationships for HIV are avoided and genetic patterns, such as those published recently from Montreal, show great promise in guiding effective HIV control. Inference robustness assessment methods involving switching between various non-linear model forms will enhance the information that can be extracted from HIV sequences.







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