**5. Vector borne diseases and climate change**

Another important aspect of the ongoing CC, and a source of indirect evidence for global warming, is the gradual evolution in disease vector distribution [8, 62]. An 'infectious vector' can be defined as any agent which carries and transmits an infectious pathogen into another living organism [63]. Many vector-borne diseases are characterized by a significant component of seasonality, and changing geographic distributions of vectors may significantly alter such seasonality [64, 65]. For example, higher rates of tick-borne diseases are seen during the spring to fall seasons in


**Table 1.**

*List of allergens and common reactions to those allergens.*

### *Impact of Climate Change on International Health Security: An Intersection of Complexity… DOI: http://dx.doi.org/10.5772/intechopen.96713*

eastern North America [66, 67]. With gradual temperature changes throughout the globe, we are more likely to see a change in the patterns of incidence of tick-borne illnesses [66, 67]. Moreover, novel tick-borne diseases have been on the rise, such as those carried by the Asian long-horned tick which has been found in the western hemisphere only in the past decade [66, 68]. Increased globalization and changes in environment due to global warming have been thought to increase the amount of tick-borne infections.

Some of the most common disease vectors are ticks and mosquitos. A summary of areas of prevalence and seasonality of tick- and mosquito-borne diseases are listed in **Tables 2** and **3**. When they reach sufficient magnitude, changes in environmental conditions are likely to disrupt the life cycle of various disease vectors and potentially alter the transmission of the diseases in question, including their geographic and seasonal distribution [66, 113].


### **Table 2.**

*Tick-Borne illnesses categorized by geographic distribution and yearly time range, focusing on the correlates of the highest prevalence of disease. United States and Canada jurisdictions are denoted using accepted two letter postal abbreviations.*


### **Table 3.**

*Mosquito-Borne illnesses organized by geographic area and seasonal time range characterized by the highest prevalence of disease. United States and Canada jurisdictions are denoted using accepted two letter postal abbreviations.*

Countries around the globe are actively working on prevention measures intended to curb incidence levels of various vector borne diseases [114, 115]. Examples of preventative methods include application of insecticide spray, installing insecticide screens, improving sanitation methods, genetic modification *Impact of Climate Change on International Health Security: An Intersection of Complexity… DOI: http://dx.doi.org/10.5772/intechopen.96713*


### **Table 4.**

*Common food and water borne illnesses and their source of contamination.*

of vectors, as well as vector control through prophylactic treatment for travelers. Many countries are also intensifying awareness and education campaigns focusing on vector borne illness to help maintain prevention methods [114–117].

### **6. Food and water borne diseases**

Global CC exerts impact on rainfall, humidity, length of growing season, and other environmental factors that are vital to the development of certain crops [118, 119]. Shifting environmental factors, along with the emergence of biofuels, are pushing food producers to implement various techniques that increase the yield of the crops [120]. One such method involves treating crops with antibiotics. However, unintended consequences of longer growing seasons and higher crop yields have resulted in greater frequency and intensity of food- and water-borne illness (**Table 4**) [121, 122]. Another way of coping with CC in terms of international food security is the introduction of insect-based, microbial/fungal-based, and laboratory-based food substitutes [123–129].

Of note, salmonella and campylobacter infections tend to be more common when the climate is warmer [130]. Relevant to human consumption, these bacteria have been shown to have higher growth rates at warmer temperatures during food preparation and storage [131], which in turn corroborates one possible relationship between CC and emerging human disease patterns.

The effect of CC on water borne diseases is equally important, yet it appears to be disproportionately neglected [132]. It is well known that precipitation can influence the transport and dissemination of infections, especially as it relates to existing water and sanitation systems [133]. More direct impact of the above can be seen during the increasingly more frequent coastal flooding as it relates to sea-level rise. Due to various factors, including human activity, water contamination exposes local populations to a variety of potential fecal-oral pathogens [134]. Indirect factors affecting the overall risk of water-borne infection propagation include changes in temperature and humidity, leading to alterations in pathogen lifecycle and survival, up to and including the creation of environments where new patterns of geographic disease spread emerge [135]. The effects of CC on water borne diseases, both indirect and direct, can be profound and unpredictable, mandating that dedicated scientific research efforts in this critically important area are increased.
