**2. Climate change and respiratory health**

The extent to which outdoor and indoor environments affect the respiratory health is established for chronic diseases such as asthma, COPD, and cardiovascular diseases, but less is known about the underlying mechanisms of their impact on infectious diseases of the respiratory system. Climate change is claimed to be a great global health concern. The impact of industrialization and anarchic urbanization in developing countries contributes to high production of greenhouse gases, carbon dioxide (CO<sup>2</sup> ), methane (CH4 ), etc., which affect the earth temperature. The monthly average temperature is increasing leading to many weather-related events such as heat waves, humidity, precipitations, floods, storms, dry conditions, and wildfires, which affect differently the environment and human health between temperate and tropical regions [7, 8]. The increased morbidity and mortality due to ALRTI in children and adults over 65 years are linked to many risk factors, the additional effect of weather change could be powered by the inadaptability of the metabolism of these vulnerable populations to heat stress and temperature variations; emphasizing the need for further research addressing health effects of climate variations. Strategies addressing climate change are getting more and more relevant to give strong support to clean environment. There is a need to better understand the underlying mechanisms of the human, animal, or plant reactions to the changing weather to develop appropriate policies with a real impact on the susceptibility of humans to deleterious effects of the phenomenon. New technologies are underdeveloped to address the physiological responses of human and animal to the environmental-induced stress and survival, relaying on DNA/RNA sequencing as reported by Biggar et al. [9]. Stress biology research will allow implementation of targeted responses to the health effects of climate change. Direct or indirect health effects act through warming temperatures with increase in atmospheric ozone, nitrogen oxide, particulate matter (PM), sulfur dioxide, and ultraviolet (UV) radiation, resulting in many conditions such as: exacerbations of chronic respiratory diseases (asthma, COPD) and respiratory infections, as well as nonrespiratory diseases including heat stress, water-borne diseases, transmittable diseases (malaria), and malnutrition.

According to the setting of occurrence, pneumonia is characterized as community acquired (CAP) or nosocomial, the latter occurring in the hospital after at least 48 h of admission or in a patient who has been hospitalized within the last 3–6 months and received antimicrobial treatment. Hospital-acquired pneumonia (HAP) includes really hospital acquired, ventilatoracquired pneumonia (VAP), and healthcare-associated pneumonia (HCAP) with extension to

CAP represents a disease contracted out of the hospital, in the community. Clinical features allow the categorization in classic pneumonia due to bacteria such as *Streptococcus pneumoniae*, *Haemophilus influenzae* type b, *Staphylococcus aureus,* and viruses such as respiratory syncytial virus (29%) and influenza virus (17%); most prevalent in children and influenza virus most common in adults [4]. Atypical pneumonia results from the infection with intracellular bacteria such as Chlamydia and Mycoplasma. Nosocomial pneumonia may affect ventilated patients or not and the former group is identified as ventilator-associated pneumonia (VAMP) with a greater risk of multidrug resistance and subsequent poor prognosis. Pneumonia in the immunosuppressed host is a severe form of the disease, which may affect individual what-

Many traditional risk factors have been previously identified including extreme age (children under 60 months and adults aged ≥65 years), poverty, and comorbidities. Malnutrition, low birth weight, nonexclusive breast-feeding, lack of measles vaccination, outdoor and indoor air pollution and crowding, mother's education, parental smoking, vitamin A and/or zinc deficiencies are thought to influence children susceptibility to infections in developing countries. Possible additional risk factors thought to increase the susceptibility to respiratory infections and allergic diseases include climate change with the potential of affecting dispersion, timing, and quality of aeroallergens and the lifecycle of some vectors of diseases, high altitude,

This chapter aims to recall the epidemiology, diagnosis, and treatment of pneumonia, with a focus on the impact of climate change and related risk factors on acute low tract respiratory

The extent to which outdoor and indoor environments affect the respiratory health is established for chronic diseases such as asthma, COPD, and cardiovascular diseases, but less is known about the underlying mechanisms of their impact on infectious diseases of the respiratory system. Climate change is claimed to be a great global health concern. The impact of industrialization and anarchic urbanization in developing countries contributes to high pro-

temperature. The monthly average temperature is increasing leading to many weather-related events such as heat waves, humidity, precipitations, floods, storms, dry conditions, and wildfires, which affect differently the environment and human health between temperate and

), methane (CH4

), etc., which affect the earth

disease affecting patients in nursing homes and in dialysis services [4].

ever the setting, with a poorer prognosis due to the underlying immune status.

humidity, and concomitant diseases [5, 6].

**2. Climate change and respiratory health**

duction of greenhouse gases, carbon dioxide (CO<sup>2</sup>

infection (ALTRI).

36 Contemporary Topics of Pneumonia

Heat waves, floods, wildfires may influence the incidence of respiratory infection through the shift in the epidemiology of climate sensitive pathogens. The threat on global health are highlighted by many previous studies such as one report from Australia about an increased incidence in childhood pneumonia associated with sharp temperature drops from 1 day to the next [10], or the outbreak of Hantavirus, which occurred in Panama in 2000, linked to the increase in rodent population attributed to a substantial increase in rainfall [11]. A report from Japan about aspergillosis among survivors of tsunami in 2011 is one more illustration of the link between climate change and respiratory health [12].

Respiratory infection results from inhaled aerosols or hematogenous spread of pathogens. Pathogen-related compounds (virulence, concentration, survival) or host related (immunity, comorbidities, aging) play a key role in the incidence and severity of the illness. Climate alterations could impact the disease by affecting the vectors or the host immunity [13]. The seasonality of respiratory infections has been demonstrated for influenza and streptococcal pneumonia during winter months in temperate climate [14, 15]. The later study reported a 2% incidence of CAP for all overnight hospital admissions, with a significantly higher rate during winter and spring, mainly in December and January [15].

Possible explanations of the seasonality seem to be the closer contact as a result of indoor crowding, lower humidity, induced variations in the human immune responses, indoor air pollution, low exposition to sunlight and ultraviolet (UV) radiation, keeping in mind the bactericidal effect of the latter [16]. In tropical regions, climate change also affects the pattern and seasonability of infections. Temperature, moisture and dehydration, and UV light greatly influence the pathogen cycle and survival in the environment and act on the transmission of air-borne aerosols. Dry air and wind-driven atmospheric pollutants could act on mucociliary escalator of the respiratory mucosa, impairing its defense mechanisms [17], and there is evidence from animal and human studies for the induced weaknesses of the immune system during winter [18]. Immune system is also under influence of adrenocortical hormones known to be more expressed during winter season than summer, and increased secretion of steroids is associated with immunodeficiency [19]. The rainy period is more prone to water-borne diseases such as cholera following floods and storms. The changing pattern in vector and pathogen infectivity, the low exposure to sunlight during rainy seasons, people spending more time indoor in crowded environment, with subsequent seasonal variations in vitamin D levels could explain the seasonability of infectious diseases. The deficiency in vitamin D linked to the reduced exposure of skin surface to sunlight has harmful effect on human immunity [20, 21] and could increase the vulnerability to infections, mainly in people at extreme ages.

Biggar et al. have illustrated the relevance of studying stress biology to characterize human responses to environmental challenges [9]; the way we will act to reduce greenhouse gas emis-

Pneumonia: A Challenging Health Concern with the Climate Change

http://dx.doi.org/10.5772/intechopen.71609

39

How the climate change could impact on the transmission and outcome of infectious diseases needs to be elucidated for appropriate preparedness of the healthy systems around the world. Health effects of air pollution are of concern; atmospheric pollutants in gaseous (mainly carbon dioxide, methane, nitrous oxide) or particulate forms may affect respiratory system according to their physical properties (solubility), their concentration, and the rate and depth of the ventilation of the subject. Use of biomass fuel for cooking in many developing countries increases the risk of exposure to outdoor or indoor pollution. Biologic agents such as fungi in indoor air could trigger the respiratory system through direct toxicity, infection, or induced immune hyperresponsiveness. Smith et al. have described the risk for pneumococcal infection in children living in a low air exchange rate environment in developing countries [31]. There is a body of evidence for the association between the increasing global main temperature and increasing global mortality [32]. The heat-related risk of mortality for respiratory diseases needs to be addressed for relevant environmental measures focusing on the one health concept. Evidence of associations between outdoor heat and respiratory hospitalizations has been reported in previous studies in developed countries, but data are lacking on the harmful effects of climate change on health in developing regions, where global warming and progressive population aging are expected with the improved accessibility to ARVs and anti-tuberculosis treatments resulting in the reduction of the mortality linked to both killers. The role of sociodemographic components and low education as well as poor accessibility to healthcare in general are strong modifiers of treatment outcomes suggesting the relevance of their regular assessment as risk factors of respiratory illnesses. Along with the changing warming climate, the role of air pollution, evidenced in respiratory exacerbations of chronic diseases such as asthma, COPD, and cardiovascular diseases, following the inhala-

, CH4, and particulate matters (PM10) (from increased forest fires, wild

urbanization, desertification) with aerodynamic diameters <10 μm is reported in many studies [32, 33]. Greenhouse gas emissions generated by human activity are pointed as the main provider of the changing Earth's climate through thermal stress, extreme weather events, and changing pattern of infectious diseases, suggesting the urgent need to develop strategies addressing human, animals, and plants health as a whole (one health concept). The climate change is expected to affect mainly vector-borne and water-borne infectious diseases, with a potential of increasing the range in case of nonadopting early preventive and warning measures [34]. Indirect effects of increased warming include shifts in vector-borne illness, increase in allergen concentration, loss of biodiversity, degradation of ecosystem, desertification, all with a negative impact on human health. Among realistic measures to reduce climate changerelated respiratory morbidity, green structures development has been considered. Whiitford et al. [35] and Burgess et al. [36] have reported the environmental benefits of green spaces on the stabilization of ecological system and the reduction of the risk of respiratory mortality. These authors showed that largest patch percentage of green structures reduces the mortality of pneumonia and lower respiratory diseases through the reduction of primary and secondary air pollutants; while their fragmentation has deleterious effect by increasing the temperature

sions will really benefit to global health.

tion of ozone, SO<sup>2</sup>

, CO2

Previous studies have emphasized the harmful role of ambient air pollution and particulate matter and the heat effect of high temperature on daily mortality [22, 23]. Climate change stands as a new health challenge for the increasing morbidity due to respiratory and cardiovascular diseases worldwide. These changes affect physical and biological systems through environmental conditions including air and water pollution, water heating, increasing the risk of transmission of water-borne pathogens. The impact of air pollution on chronic respiratory diseases such as asthma and COPD is well established. The extent to which weather patterns could influence respiratory infections is still debatable. Heat, air pollution, change in quantity and quality of aeroallergens, and shift in infectious diseases linked to changing ecology of the pathogens have been previously reported as strong risk factors affecting respiratory health. Direct health effects of climate changes include heat-related illness, exacerbations of chronic cardiorespiratory diseases such as COPD and asthma due to the changing pattern of environmental exposure [24]. Previous epidemiological studies suggest the seasonal variability of respiratory infections, but the pathobiology of this link is far from being clearly assessed. Cold and dry conditions in temperate regions power the transmission of influenza and respiratory syncytial viruses, while the wet conditions of the tropics seem to reduce the aerosol transmission of the influenza virus [25]. Studies addressing the link between climate change and pneumonia still need to be conducted worldwide, mainly in poor resource countries and also in the most affected by lack of hygiene and unpreparedness. Lower respiratory tract infections seem to be more frequent during winter in temperate areas and during rainy season in tropical regions [25, 26]. Studies in Hong Kong [27] and China [28], respectively support the impact of the changing weather pattern on the magnitude of respiratory infection and the seeking of emergency healthcare. The pattern of seasonality on viral respiratory infections has clearly been reported in temperate countries, but data from tropical regions are sparse [29]. The vulnerability of children under the tropics could be emphasized by poverty-related conditions such as malnutrition and helminth infections as well as poor access to healthcare facilities. Chronic helminth infections stimulate the T-cells to produce more Th2 type cytokines (IL-3, IL-5, IL-13) than Th-1 profile (IL-2, IFN-gamma). This imbalance could be a possible explanation for the increased susceptibility to bacterial infections in affected individuals. Lozano et al. have illustrated the negative role of air and water pollution linked to storms and floods affecting agricultural products. These authors reported an increase in pneumonia deaths in children under 5 years due to malnutrition [30]. Malnutrition predisposes to immunosuppression through lack of many elements or oligo-elements such as zinc and cupper, involved in the functionality of many components of the immune system. Biggar et al. have illustrated the relevance of studying stress biology to characterize human responses to environmental challenges [9]; the way we will act to reduce greenhouse gas emissions will really benefit to global health.

studies for the induced weaknesses of the immune system during winter [18]. Immune system is also under influence of adrenocortical hormones known to be more expressed during winter season than summer, and increased secretion of steroids is associated with immunodeficiency [19]. The rainy period is more prone to water-borne diseases such as cholera following floods and storms. The changing pattern in vector and pathogen infectivity, the low exposure to sunlight during rainy seasons, people spending more time indoor in crowded environment, with subsequent seasonal variations in vitamin D levels could explain the seasonability of infectious diseases. The deficiency in vitamin D linked to the reduced exposure of skin surface to sunlight has harmful effect on human immunity [20, 21] and could increase the vulnerability to infec-

Previous studies have emphasized the harmful role of ambient air pollution and particulate matter and the heat effect of high temperature on daily mortality [22, 23]. Climate change stands as a new health challenge for the increasing morbidity due to respiratory and cardiovascular diseases worldwide. These changes affect physical and biological systems through environmental conditions including air and water pollution, water heating, increasing the risk of transmission of water-borne pathogens. The impact of air pollution on chronic respiratory diseases such as asthma and COPD is well established. The extent to which weather patterns could influence respiratory infections is still debatable. Heat, air pollution, change in quantity and quality of aeroallergens, and shift in infectious diseases linked to changing ecology of the pathogens have been previously reported as strong risk factors affecting respiratory health. Direct health effects of climate changes include heat-related illness, exacerbations of chronic cardiorespiratory diseases such as COPD and asthma due to the changing pattern of environmental exposure [24]. Previous epidemiological studies suggest the seasonal variability of respiratory infections, but the pathobiology of this link is far from being clearly assessed. Cold and dry conditions in temperate regions power the transmission of influenza and respiratory syncytial viruses, while the wet conditions of the tropics seem to reduce the aerosol transmission of the influenza virus [25]. Studies addressing the link between climate change and pneumonia still need to be conducted worldwide, mainly in poor resource countries and also in the most affected by lack of hygiene and unpreparedness. Lower respiratory tract infections seem to be more frequent during winter in temperate areas and during rainy season in tropical regions [25, 26]. Studies in Hong Kong [27] and China [28], respectively support the impact of the changing weather pattern on the magnitude of respiratory infection and the seeking of emergency healthcare. The pattern of seasonality on viral respiratory infections has clearly been reported in temperate countries, but data from tropical regions are sparse [29]. The vulnerability of children under the tropics could be emphasized by poverty-related conditions such as malnutrition and helminth infections as well as poor access to healthcare facilities. Chronic helminth infections stimulate the T-cells to produce more Th2 type cytokines (IL-3, IL-5, IL-13) than Th-1 profile (IL-2, IFN-gamma). This imbalance could be a possible explanation for the increased susceptibility to bacterial infections in affected individuals. Lozano et al. have illustrated the negative role of air and water pollution linked to storms and floods affecting agricultural products. These authors reported an increase in pneumonia deaths in children under 5 years due to malnutrition [30]. Malnutrition predisposes to immunosuppression through lack of many elements or oligo-elements such as zinc and cupper, involved in the functionality of many components of the immune system.

tions, mainly in people at extreme ages.

38 Contemporary Topics of Pneumonia

How the climate change could impact on the transmission and outcome of infectious diseases needs to be elucidated for appropriate preparedness of the healthy systems around the world. Health effects of air pollution are of concern; atmospheric pollutants in gaseous (mainly carbon dioxide, methane, nitrous oxide) or particulate forms may affect respiratory system according to their physical properties (solubility), their concentration, and the rate and depth of the ventilation of the subject. Use of biomass fuel for cooking in many developing countries increases the risk of exposure to outdoor or indoor pollution. Biologic agents such as fungi in indoor air could trigger the respiratory system through direct toxicity, infection, or induced immune hyperresponsiveness. Smith et al. have described the risk for pneumococcal infection in children living in a low air exchange rate environment in developing countries [31]. There is a body of evidence for the association between the increasing global main temperature and increasing global mortality [32]. The heat-related risk of mortality for respiratory diseases needs to be addressed for relevant environmental measures focusing on the one health concept. Evidence of associations between outdoor heat and respiratory hospitalizations has been reported in previous studies in developed countries, but data are lacking on the harmful effects of climate change on health in developing regions, where global warming and progressive population aging are expected with the improved accessibility to ARVs and anti-tuberculosis treatments resulting in the reduction of the mortality linked to both killers. The role of sociodemographic components and low education as well as poor accessibility to healthcare in general are strong modifiers of treatment outcomes suggesting the relevance of their regular assessment as risk factors of respiratory illnesses. Along with the changing warming climate, the role of air pollution, evidenced in respiratory exacerbations of chronic diseases such as asthma, COPD, and cardiovascular diseases, following the inhalation of ozone, SO<sup>2</sup> , CO2 , CH4, and particulate matters (PM10) (from increased forest fires, wild urbanization, desertification) with aerodynamic diameters <10 μm is reported in many studies [32, 33]. Greenhouse gas emissions generated by human activity are pointed as the main provider of the changing Earth's climate through thermal stress, extreme weather events, and changing pattern of infectious diseases, suggesting the urgent need to develop strategies addressing human, animals, and plants health as a whole (one health concept). The climate change is expected to affect mainly vector-borne and water-borne infectious diseases, with a potential of increasing the range in case of nonadopting early preventive and warning measures [34]. Indirect effects of increased warming include shifts in vector-borne illness, increase in allergen concentration, loss of biodiversity, degradation of ecosystem, desertification, all with a negative impact on human health. Among realistic measures to reduce climate changerelated respiratory morbidity, green structures development has been considered. Whiitford et al. [35] and Burgess et al. [36] have reported the environmental benefits of green spaces on the stabilization of ecological system and the reduction of the risk of respiratory mortality. These authors showed that largest patch percentage of green structures reduces the mortality of pneumonia and lower respiratory diseases through the reduction of primary and secondary air pollutants; while their fragmentation has deleterious effect by increasing the temperature and the air pollutants. Green spaces are shown to block secondary air pollutants (ozone and PM 2.5). Rationale management of green structures needs to be encouraged in the urbanization policies among other preventive measures to improve respiratory health [37–39].

rate of mortality caused by diarrheal and low tract infection diseases remains high and the major cause of early deaths in the country. The big five, COPD, asthma, low respiratory tract infections, TB, and lung cancer are among the most common causes of severe illness death worldwide.

Pneumonia: A Challenging Health Concern with the Climate Change

http://dx.doi.org/10.5772/intechopen.71609

41

The lack of standardized protocols and regular statistic reports does not allow the assessment of accurate incidence rate of CAP across the sub-Saharan region. In Europe, this incidence rate in adults is between 1.07 and 1.2 per 1000 person year and 1.54 and 1.7 per 1000 population according to a report by Torres et al. [48]. Older age and underlying comorbidities including COPD, cardiovascular and liver diseases, diabetes, cancers as well as all causes of immunosuppression (steroids treatment, malnutrition, HIV-AIDS) affect the prognosis of the disease and this is highlighted by the CURB 65 criteria in use for assessing the severity of CAP. There is a regular increase in the incidence of CAP worldwide, may be associated to demographic changes, increasingly aging population, growing poverty, low accessibility to healthcare facilities, precarity and war displacements, smoking and alcohol consumption. It is more and more clear that air pollution and climate change play important roles in the rising morbidity and mortality related to respiratory diseases. The heat stress linked to the warming of the climate induces environmental changes allowing the emergence of new pathogens worldwide.

The real involvement of these ecological modifications needs to be addressed.

Pneumonia could result from infectious pathogens including bacteria, viruses, fungi, and parasites, or from noninfectious agents, of physical or chemical nature (aspiration pneumonia, gas inhalation). The main route for bacterial contamination is bronchogenic dissemination following microaspiration of pharyngeal secretions. Hematogenous spread follows bloodstream invasion by pathogens; and infection could also spread from contiguous tissues. In the alveolar space, host local defenses through humoral or cellular-mediated immune responses or mechanical processes (mucociliary escalator, cough reflex) when overwhelmed, allow the infection onset. The inflammation in the lung structures results in the release of mediators and accumulation of an exudate impairing the local immune system. The thickening of the alveolocapillary membrane alters the gas diffusion, inducing hypoxemia. The mismatch in the ventilation-perfusion ratio due to the reduced minute-ventilation increases the hypoxemia. Pneumococcal carriage in the posterior nasopharynx is a prerequisite for the development of pneumonia due to *S. pneumoniae*. Human to human transmission occurs through inhaled aerosols or close contact. The virulence of the pathogen is carried by factors allowing adhesion to the respiratory epithelium and released virulence factors such as pneumolysin and neuraminidase, which can damage the lung structures. The concentration of the pathogens is also a requirement for the onset of disease. Host immunity through humoral- and cell-mediated immunity is the main way of defense. Airway epithelium secretes also lactoferrin with the potential of deprecating the pathogen from iron, and then impairing the growth of the bacteria. Lysozyme and human defensins are along with cathelicidin-related antimicrobial peptides LL-37, also involved in the lysis of bacteria [49]. The classic evolution of acute pulmonary inflammatory response will turn in red hepatization, gray hepatization, and resolution. Main causes of CAP are *S. pneumoniae*, *M. pneumoniae*, *H. influenzae*, *C. pneumoniae*, *Legionella* sp., or respiratory virus with influenza A and B, respiratory

**3.2. Pathophysiology**
