Neuroepidemiology and the epidemiology of viral infections of the nervous system

Viral infections result in a tremendous burden of neurologic illness worldwide. Although many viral etiologies of neurologic infectious disease have been recently controlled through vaccination and other public health measures, the emergence of new pathogens and the re-emergence of previously controlled pathogens remain significant global public health challenges. One of the fundamental bases for understanding the dynamics of viral nervous system infections is through epidemiology – the science of assessing patterns of disease in populations and the factors that influence these patterns. Neuroepidemiology is a discipline that applies epidemiologic principles and practices to neurologic disease. There are several characteristics of neurologic illness that necessitate the subdiscipline of neuroepidemiology. This chapter reviews some of the basic terms and concepts of neuroepidemiology, including epidemiologic analysis and studies. It then applies these concepts to infections of the nervous system, including encephalitis, aseptic meningitis, acute myelitis, prion diseases, and slow virus infections. The chapter then addresses the epidemiology of emerging and re-emerging viral neurologic diseases as well as the factors driving these emergences. The epidemiology of viral nervous system diseases will undoubtedly continue to change and expand, and as we gain a better understanding of this epidemiology and the pathophysiology of viral infections, this will hopefully lead to improved surveillance, diagnostic, treatment, and prevention strategies for these illnesses.