Áhrif loftslagsbreytinga á smitsjúkdóma í Evrópu

Dr. Shlomit Paz, prófessor við háskólann í Haifa flytur fyrirlesturinn Áhrif loftslagsbreytinga á smitsjúkdóma í Evrópu (Climate change impacts on vector-borne diseases in Europe: current situation, projection and recommendations).

Ágrip á ensku

Europe is experiencing a warming trend with more frequent hot spells, longer and warmer summers, and an increase in the frequency, duration and severity of heat waves. Water availability has also changed due to a decrease in the amount of precipitation in Southern and Eastern Europe and conversely, an increase in the frequency and severity of heavy rainstorms and floods in Northern Europe.

Vector-borne diseases (VBDs) are mainly transmitted by arthropod vectors such as mosquitoes. VBDs are highly sensitive to climatic change since a warmer climate and changing rainfall patterns may create hospitable environments for both vectors and pathogens. Climate variability has significant impacts on the eruptions, adaptation, and geographic range expansion of vectors and pathogens, and on their survival, reproduction and distribution. Although weather conditions contribute in a nonlinear way to VBD transmission, they are a significant key driver of VBDs emergence, re-emergence, and spread to new geographical areas, including non-endemic regions.

An alarming example is the spread of West Nile Fever (WNF), caused by the West Nile Virus (WNV), in Europe. This member of the Flaviviridae family of viruses circulates between birds and ornithophilic mosquitoes, particularly members of the genus Culex. Under suitable environmental conditions, it spreads and infects humans and horses and often causes regional outbreaks. While WNV was originally endemic to Africa, following heat conditions, outbreaks of WNF have erupted since 2010 in southern and eastern-European countries such as Greece, Turkey and Romania and furthermore, WNF cases have been detected in recent years in northern locations in Germany and in the Netherlands.

Pathogens may be dispersed into non-endemic regions through travel, trade or migration while autochthonous transmission (i.e. cases with no travel history, two weeks before the disease onset) can then occur in areas where the vector is established and where climatic conditions are favorable for transmission. Due to increasing urbanization and globalization, the risk of local outbreaks of dengue and chikungunya across Europe is increasing while global warming increases climatic suitability for Aedes albopictus, an invasive mosquito species acting as a vector for the dengue and chikungunya viruses. Local (autochthonous) outbreaks of dengue and chikungunya have occurred over the last years in southern Europe when infected travelers passed the pathogen to the mosquito vector, which in turn caused secondary cases of human infection. For example, in France, following high temperatures during the spring and summer of 2022 which promoted vector activity and transmission efficacy of dengue virus, the number of autochthonous cases of dengue achieved the highest record and the maximal number among the EU countries. That geographical spread of autochthonous cases from the Mediterranean areas both westward and northward reflects the colonization of new territories by A. albopictus, raising a public health concern.

As the climate crisis is worsening and predictions show an increasing potential of a spread of VBDs, actions are needed to prevent sustained outbreaks and their endemicity establishment in the future. Preparedness and response, risk assessment, and early warning systems, along with climate change adaptation are essential in order to mitigate the impacts of the climatic changes on the (re-) emergence of VBDs and to prevent their negative consequences for population health.