ABSTRACT
Viral diseases of the nervous system are ancient and poliomyelitis was described in Egypt as early as 2000 BC. They can cause a wide range of neurological symptoms, such as meningitis, encephalitis, meningoencephalitis, Guillain-Barré-like syndrome and stroke, often leaving mild to severe residuals. Depending on the pathogen, the symptoms appear quickly within hours, or lead to increasing chronic symptoms within 1 week or months. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was newly identified in January 2020 and occurs worldwide, illustrates the sequelae of a phenomenon that has been known for centuries, the possible rapid spread of pathogen-related infectious diseases. Due to vaccination programs some pathogens are becoming rarer or are considered to be eradicated. Nevertheless, vaccination programs, especially in the poorer regions, are repeatedly interrupted, for example by wars. The most recent example is the interruption of vaccination against poliomyelitis in Ukraine. As life expectancy continues to rise and years of life lost to infectious diseases decrease, the new infectious disease threat is likely to come from emerging and re-emerging infections; however, according to a recent analysis of population data from 29 countries, life expectancy during the corona pandemic has decreased, e.g., by 28 months in the USA and by 6 months in Germany. Climate change, rapid urbanization and changing land-use patterns could increase the risk in the coming decades. In particular, the climate change can alter the spectrum of global pathogens and especially vector-borne infections can spread to new areas. A sustained increase in travel, trade and mobility enables the pathogens to spread quickly.