Climate Change and Human Health pneumonia, whooping cough, hepatitis, diarrhea, dengue, cholera and viral encephalitis have 30-50% correlation.31 The potential health impacts of climate change are classified into two: the direct and indirect health impacts. The direct impact includes thermal stresses and weather disasters that result in immediate serious illnesses, injuries, and deaths. Indirect health impacts occur via the link of change in the transmission of infectious diseases, contamination and scarcity of water supply, and food insecurity.8,22,32 Heat stroke is another problem that is associated with increase in temperature. An individual who is exposed to extreme and prolonged heat may experience heat stress, and death may ensue. Heatstroke is the most common health condition associated to heat.33 Change in the Transmission Patterns of Diseases The indirect effects of climate change to human health occur through ecological alterations which in turn, affects food production, safety of sources of drinking water, and transmission patterns of diseases. For disease transmission, most vector-borne diseases are weather sensitive. Climatic factors influence the ecology, development, behaviour, and survival of vectors and hosts thus affecting the transmission patterns of diseases. Transmission rates and patterns and spread of vector-borne and rodent-borne diseases generally increase with global warming.3 Ecology, reproduction, parasite development, behaviour, bite frequency, and survival of vectors of various diseases also increase with rising temperature, consequently, affecting disease infection. For instance, in a study in east African highlands, it was found that there was ten-fold increase in mosquito abundance with every unit increase in temperature. In fact, Epstein 2005 noted that the resurgence and redistribution of infections involving vectors, hosts, and reservoirs –mosquitoes, ticks, and rodents- are good indicators of climate change. The two most important vectorborne diseases in tropics and subtropics are malaria and dengue fever.34-35 Malaria is the currently most widespread and serious vector-borne disease in the world. On the other hand, leptospirosis is the most widespread zoonotic disease in the world. Increasing temperature affects range of malarial transmissibility and outbreaks. Malaria cases were also found to increase with increasing temperature in the study in Kenya.3 The geographic distribution of insects is highly sensitive to temperature changes.36 Usually after heavy rainfall, there increase in epidemics/outbreaks of diseases.37 Outbreaks of leptospirosis, for instance, occur after extreme flooding or hurricane. Breeding sites of mosquitoes are created along roadways and in dirty receptacles after heavy rains. 23 Drought increases the infectivity of mosquitoes since warmer temperature speeds up the malarial parasite inside the mosquitoes.38 (Table 9) Water-borne diseases are also on the rise with increased sea surface temperature and sea level VOL. 50 NO. 2 2016 rise.8,39 In developing countries, heavy rainfall contributes to the contamination of underground water sources and surface water due to flooding, hence, coliform regrowth is expected to increase in water distribution systems.40 Table 9. Climate Change Affecting Disease Transmission8 How Climate Change Affect Diseases Transmission Shifting of the vector’s geographic range Increasing reproductive and biting rates Shortening the pathogen incubation period Decreased Food Production Climate change has implications on food production as well (8) due to variations in temperature and moisture. These two environmental parameters are significant factors in germination, growth, and photosynthesis of crops. If these parameters are altered, agricultural productivity may be affected. Plant diseases, predator-pest relationships, and water supply are also the other factors that may be triggered by climate change, which in turn, affect crop production.8,19 Famine, as noted by Kovats et al. occurs when there is climate stress on agriculture. 27 Table 10 shows how climate change affects food production. Poor health and lack of hygiene due to limited water and food supply can further result in water-borne and diarrheal diseases. Table 10. Climate Change Affecting Food Production Ways on How Climate Change Could Affect Food Production Geographical shifts and yield changes in agriculture Reduction in the quantity of water available for irrigation Loss of land through rising sea level Loss of land through rising sea level and the associated salinization Effects on fisheries productivity through rising sea level and changes in water temperatures, currents, freshwater flows and nutrient circulation. Conclusion Climate science is a wide-ranging discipline of study and research. Merely looking at the health impacts of climate change requires interdisciplinary integration of both the environmental and health sciences. This review has discussed the impact of climate change on human health. First, climate change which is a result of increased concentrations greenhouse gases in interaction chemically and physically with air-borne pollutants can cause various cardio-respiratory diseases. Second, direct health impacts of climate change attributed to climateinduced natural disasters cause increased rates of mortality and morbidity. Lastly, indirect health impacts of climate change due to ecological alterations (i.e., change in transmission patterns of vectors of infectious diseases, change in agricultural productivity, and contamination of water sources) can lead to malnutrition and increased incidences of certain diseases. As the worldwide global climate continuously changes, the Philippines will be ACTA MEDICA PHILIPPINA 97