The West African Onchocerciasis (river blindness) Control Program successfully used modeling to supplement intervention programs [13] . By using clearly delineated endpoints, these models helped convince donors and the scientific community that the aims of the program were achievable [14] . As a result, mathematical models have retained a role in subsequent policy discussions [15] . Insights from mathematical models during the SARS epidemic helped determine how serious the epidemic might become, as well as the impact of proposed control measures. These models provided important guidance to public-health authorities at a critical time when little other information was available. Insights from the models showed that, if unchecked, the virus could cause a significant epidemic, but that basic epidemiological control measures -patient isolation, contact tracing, etc -could have a substantial impact on the extent of the epidemic. Subsequently, these control measures played a major role in limiting the spread of the 2003 epidemic [16] .