Can we spend our way out of the AIDS epidemic? A world halting AIDS model

The basic reproductive ratio, R 0, is one of the fundamental concepts in mathematical biology. It is a threshold parameter, intended to quantify the spread of disease by estimating the average number of secondary infections in a wholly susceptible population, giving an indication of the invasion strength of an epidemic: if R 0 < 1, the disease dies out, whereas if R 0 > 1, the disease persists. R 0 has been widely used as a measure of disease strength to estimate the effectiveness of control measures and to form the backbone of disease-management policy. However, in almost every aspect that matters, R 0 is flawed. Diseases can persist with R 0 < 1, while diseases with R 0 > 1 can die out. We show that the same model of malaria gives many different values of R 0, depending on the method used, with the sole common property that they have a threshold at 1. We also survey estimated values of R 0 for a variety of diseases, and examine some of the alternatives that have been proposed. If R 0 is to be used, it must be accompanied by caveats about the method of calculation, underlying model assumptions and evidence that it is actually a threshold. Otherwise, the concept is meaningless.

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“…A generalised version of this formulation was used in Smith? et al [15] called T 0 . The endemic equilibrium satisfies…”

Section: A Worked Examplementioning

confidence: 99%

The Failure of R₀

Blakeley

Smith

2011

Computational and Mathematical Methods in Medicine

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184

158

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“…The goal, WHAM, the World Halting AIDS Model, [60,61] might be just a grand epidemiology simulation in the deterministic and/or stochastic moulds. However, if we let the people of the world simulate themselves through havatars, we may collectively see our way past this unfortunate pandemic, and who knows what else that may lie ahead.…”

Section: Resultsmentioning

confidence: 99%

Halting HIV/AIDS with avatars and havatars: a virtual world approach to modelling epidemics

et al. 2009

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BackgroundA major deficit of all approaches to epidemic modelling to date has been the need to approximate or guess at human behaviour in disease-transmission-related contexts. Avatars are generally human-like figures in virtual computer worlds controlled by human individuals.MethodsWe introduce the concept of a "havatar", which is a (human, avatar) pairing. Evidence is mounting that this pairing behaves in virtual contexts much like the human in the pairing might behave in analogous real-world contexts.ResultsWe propose that studies of havatars, in a virtual world, may give a realistic approximation of human behaviour in real-world contexts. If the virtual world approximates the real world in relevant details (geography, transportation, etc.), virtual epidemics in that world could accurately simulate real-world epidemics. Havatar modelling of epidemics therefore offers a complementary tool for tackling how best to halt epidemics, including perhaps HIV/AIDS, since sexual behaviour is a significant component of some virtual worlds, such as Second Life.ConclusionHavatars place the control parameters of an epidemic in the hands of each individual. By providing tools that everyone can understand and use, we could democratise epidemiology.

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“…A recent modelling study argues that by spending the available money wisely, but rapidly, eradication of AIDS will be feasible. Holding money in reserve now, could lead to extra, unnecessary infections and therefore extra costs in the future [Smith et al, 2009]. Moreover, the loss of large numbers of people who are in their working age and the resulting increase in HIV-related orphans has an enormous negative impact on economies and future generations.…”

Section: Financementioning

confidence: 99%