Molecular, Epidemiological, and Clinical Complexities of Predicting Patterns of Infectious Diseases

The prediction of the future meets an essential need of humanity but it is not possible for the human epidemics. This need results in rites and “sciences ” such as haruspices (Etruscan reading the future in entrails of animals) and augurs (Romans reading the flight of birds). They are as old as the human history makes it possible to know. The scientific knowledge in astronomy gives the impression to be able to predict the events of the future thanks to observation of the events of the past. Thus astrology was initially developed by the astronomers such as Ptolemy, who, by their capability to predict the moon’s eclipses and the planets movements, were considered like magicians. This vision of the world still remains very vivid since XXV centuries and it is easy to see the echo of it, in all the countries of the world where astrology remains extraordinary prevalent. Concerning the epidemics, the temptation to predict the future is also important, even more so as politicians are accused of incompetence when an unexpected outbreak appears. This is linked with the reluctance to accept stochastic events. This brought about the development of mathematical models of epidemiology, of which none have been proven to be efficient, but that influenced the human society in a considerable way through the media. Among the examples for which we are involved are mad cow disease (which was predicted to cause hundreds of thousands of deaths), the prediction on evolution of the epidemic of AIDS (that was contradicted by a rapid decline in Africa in the middle of the 90th), the avian influenza (which predicted that the virus was going to be transformed into an agent of inter-human disease), the dramatic decline of Malaria in Africa (that was unpredicted), and, finally, the recent episode on the swine flu. This episode of A-H1N1 “swine flu” pandemics highlighted the scope of our ignorance by associating elements which had never been seen in the pandemic or seasonal flu (Nougairede et al., 2010).