**3. Impact of climate change and environmental modifications on health and vector-borne diseases**

Climate change and environmental modifications are the main determinants of the changes observed in ecosystems that favor the occurrence of emerging

#### *Vector-Borne Diseases and Climate Change in the Environmental Context in Haiti DOI: http://dx.doi.org/10.5772/intechopen.96037*

and re-emerging animal and human diseases. More than ever, veterinary and health authorities around the world have realized the need to better understand the problem of climate loading and environmental change as it is posed in the 21st century in order to be able to prepare viable alert and response plans to these diseases, particularly vector-borne diseases whose proliferation appears to be closely linked to climatic parameters such as heat and humidity [20]. This situation is further complicated in countries such as Haiti, where significant environmental changes have been recorded in recent decades in terms of both forest cover and water resources.

Climate variability and change cause many cases of mortality and disease in humans and terrestrial and aquatic animals through the natural disasters they cause, such as heat waves, floods and droughts. The latest report of the Intergovernmental Panel on Climate Change (IPCC) has clearly shown that human activity is affecting the world's climate and has highlighted that this has multiple impacts on human and animal health.

#### **3.1 Proliferation of vectors responsible for animal diseases and zoonosis**

For about four decades, the scientific community and a large part of the civil society of developed countries have not failed to express their concern about the threat of a catastrophe looming over the planet if certain countries, major producers of greenhouse gases, persist in refusing to change their modes of industrial production which are largely responsible for the present situation. In the history of humanity, never before have there been so many massive emissions of such gases that have caused pronounced climatic disturbances that are reflected, among other things, in changes in rainfall patterns according to regions and the occurrence of extreme weather events. It is agreed that such climatic upheavals are at the root of many emerging or re-emerging infectious diseases. Indeed, it has long been known that there is a positive correlation between climate change and the occurrence of these diseases. Indeed, the temperature of arthropods/vectors generally varies according to that of the environment in which they live, hence their high sensitivity to ambient temperature variations. These temperature variations, by acting on the biology of these vectors, interact with the infectious agents that they often harbor [21].

In addition to temperature variations, other factors such as rainfall and humidity also contribute to the creation of favorable environments for vector development [3]. Changes in land use and socio-economic factors (human behavior, movement of people and goods, etc.) have also contributed to increasing ecological imbalances conducive to vector proliferation, resulting in the introduction and local transmission of new emerging pathogens in many countries [22]. However, the role of climate in the occurrence of infectious diseases, particularly vector-borne diseases, is not easily established.

This has led the IPCC to issue constant alerts about changes in the transmission of infectious diseases by vectors such as mosquitoes and ticks [23]. The sudden appearance and spread in 2007 and 2014 in many countries, tropical and temperate, of a vector-borne disease such as Chikungunya, which was facilitated by the extension of the distribution area of Aedes mosquitoes and the greater mobility of human populations. A similar scenario probably occurred in other temperate countries with other vector-borne diseases such as dengue and Zika as new areas of mosquito vector proliferation were established. Mosquito-borne diseases are climate-sensitive because the risk of epidemic disease increases or decreases in part with temperature, rainfall and humidity, which affect the life and reproductive cycle of insects [5].
