Climate changes and emerging diseases

Increasing temperatures, but also other climatic factors, will have an impact on human health. Apart from the direct consequences of extreme weather conditions (e.g., heat-related fatalities), indirect health consequences in the long-term are also of great importance. In addition to a likely increase in allergic diseases and additional complications in the course of cardiovascular and respiratory diseases, infectious diseases are of particular interest. In Germany, endemic pathogens, such as hantavirus (with its reservoir in small rodents), tick-borne pathogens (Borrelia burgdorferi, tick-borne encephalitis virus), and certain food- and water-borne pathogens, are of concern. Mild winters favor rodent populations and may result in hantavirus epidemics in the subsequent summer period. Statistical analyses show a significant association between temperature and campylobacter incidence in Germany. An outbreak of rodent-borne leptospirosis among strawberry harvesters enhanced by heavy rainfalls illustrates how weather conditions may influence disease occurrence. Pathogens that are non-endemic in Germany but are imported by humans, vectors, and reservoir animals pose an additional risk to the population. Increasing temperatures improve the conditions for establishment of new vectors and for autochthonous transmission of some pathogens (e.g., chikungunya, dengue, West Nile virus, malaria, or leishmaniasis). Climatic and ecologic conditions in Germany currently do not favor autochthonous outbreaks for most of these pathogens. However, if temperatures increase, as expected, such outbreaks will become more likely. Germany should enhance its research in public health activities in the field of climate change and infectious diseases.