**3.2 Increasing prevalence and incidence rates of emerging or re-emerging diseases**

Epidemic peaks are generally linked to climatic disturbances, as was the case in 2015 with the El Niño phenomenon, which led to the resurgence of malaria, chikungunya, Zika, plague and dengue fever. Since 1950, 2015 was the most important year in South America for Zika virus infection. Researchers have identified four school cases worldwide: plague and hantavirus in the United States, cholera in Tanzania, and dengue fever in Brazil, Thailand and Indonesia [3, 24]. **Figure 2** shows the emergence of several epidemic diseases around the world during the El Niño phenomenon of 2015-2016 [24].

Researchers have been interested in the high prevalence and especially the high incidence rate of Buruli ulcer observed in French Guyana since 1969. They compared the changes in rainfall in the region with the evolution of the number of Buruli ulcer cases over the past 40 years and showed that the reduction in rainfall and its runoff has led to the multiplication of areas of stagnant residual water serving as a breeding ground for the bacterium Mycobacterium ulcerans responsible for Buruli ulcer. This observation is not consistent with the generally accepted idea that reduced rainfall leads to a decrease in the prevalence of infectious diseases. On the contrary, it has been observed that swampy habitats, with the reduction of rainfall, have become more accessible and usable, thus increasing the level of human exposure to the bacteria still present in the aquatic environment.

## **3.3 Highlighting the interrelationships between health, biodiversity and ecosystems**

Ecosystem change includes climate change, environmental change and related relationships and is believed to be closely associated with many emerging diseases [25]. The interrelationships between health, agriculture and ecosystems open a fairly broad door to the "One health" approach. They highlight how:

#### **Figure 2.**

*Emergence of several epidemical diseases across the globe during the El Niño phenomenon of 2015–2016. The four cases studied in detail (United States, East Africa, Brazil and Southeast Asia) are boxed in red [24].*

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


It is currently recognized that infectious and parasitic diseases have medical, social and environmental dimensions and that public health actors must strive for a holistic, comprehensive approach to better understand the dynamics of their development, particularly those that are zoonotic. To this end, a strategy should be adopted that integrates data or advances from public health, animal health, agriculture and environmental sciences in order to identify the determinants and risk factors associated with the various health states at the Human/Animal/Environment interface. Such an approach is related to the "One Health, One Health" approach and requires, to ensure its success, a new form of collaboration that requires the formation of multidisciplinary teams of scientists and the establishment of a platform for intersectoral cooperation at the institutional level.

In order to better manage the emergence or spread of zoonosis effectively, the ecological requirements of zoonotic pathogens and also the importance of anthropogenic factors must be taken into account. The unprecedented anthropogenic pressure on ecosystems in the context of global environmental change, which is constantly increasing, will continue to promote the occurrence of zoonotic diseases [26]. Thus, deforestation is a frequent source of emergence of zoonosis from wild animals. This is the case for diseases caused by West Nile virus and Nipah virus [27]. It is therefore important to consider the conditions of their emergence in relation to the environment and/or the organization of animal production chains, with particular emphasis on social factors (organization and functioning of animal husbandry and marketing structures). The governance of territories or geographical areas is another aspect that needs to be taken into consideration when organizing health management [28].

The CDC has presented a very good illustration of the impact of climate change on Human Health in the following **Figure 3** [4].

CIRAD has developed an integrated approach to health that is a little broader than the conventional concept of "One Health", which seems to us to be quite interesting, and which is based around the following major axes:


**Figure 3.**

*Impact of Climate change on public Health [4].*

management), agricultural or rural development sectors, and on the other hand, categories of social actors such as stockbreeders and farmers, peasant leaders, buyers and sellers of animal products as well as religious authorities.

The environment is continually changing. Therefore, this permanent change must be accompanied by adaptive and participatory methods to facilitate decisionmaking, which is quite complex for public health actors. The more complex the health problem is, the more the actors must learn to manage this uncertainty related to decision making. This is why some experts propose a participatory modeling and simulation approach to guide consultation and decision-making. This approach is largely inspired by companion modelling [28].

The tools used lead the actors concerned by health in a given territory to cooperate, even though they do not necessarily know each other or work together. These tools enable them to work together to build a shared representation of a complex situation and to simulate actions and their effects in order to build consensual solutions. This approach also offers the possibility of integrating health control and surveillance actions into the territorial context. It can therefore accompany health management interventions, such as vaccination, drug distribution or surveillance and the emergence of new clinical cases in human or animal populations.
