Climate change and its adverse impacts on health

This article was exclusively written for the Sting by Mr Peter Mac Jajua, medical student from Sierra Leone who is affiliated to the International Federation of Medical Students Associations (IFMSA). However, the opinions expressed in this piece belong strictly to the writer and do not necessarily reflect IFMSA’s view on the topic, nor The European Sting’s one. Climate is the statistical weather condition of a place over a long a period of time. While the weather can change in minutes or hours a change in climate is something that develops over longer periods of decades or centuries. It is defined not only by average temperature and precipitation, but also by the type, frequency, duration, and intensity of weather events such as heat waves, cold spells, storms, flood and drought. Climate change is expected to alter temperature, precipitation and air movement in various ways and to a varying degree. And this will have important consequences for human health, environment and economy. Health, according to WHO definition of health in 1947, is a state of complete physical, mental, and social well-being and not merely the absence of disease and infirmity. In more recent times the word has taken on a holistic approach. Payne, Hahn, and Mauer describe health in terms of six interacting and dynamic dimensions, which include physical, emotional, social, intellectual, spiritual and occupational. With this, thus health can be defined as a dynamic state or condition that is multi-dimensional in nature and results from a person’s adaptation to his or her environment. With this in mind any condition or factor that leads to changes in the environment or surrounding can have either direct or indirect impact on health. Health is a source of living and it exists in varying degrees. Climate change and health refers more specifically to the relationship between current and future anthropogenic climate change and conditions of health. For example it is evident that the prevalence of malaria in parts of Africa is related to the tropical climate in parts of Africa. In future however the nature and spread of malaria may be affected by the changes in temperature and precipitation expected in Africa. In general climate change will lead to increasing or decreasing the prevalence of disease, injury and other health issues. Health consequences related to the impacts of climate change will be experienced by nations or countries most vulnerable to climate change in the world and these nations are mostly from Africa, Asia, and North America. This vulnerability is due in part to existing problems of poverty, weak institutions and armed conflict. This has limited the capacity of these nations to deal with the additional health changes posed by climate change. These nations also lack the adequate knowledge and technical knowhow to mitigate or adapt to challenges or threats posed by climate change. Therefore, the relative importance of climate and socioeconomic factors is difficult to quantify. The majority of human health problems that can be linked to climate change are not strictly speaking created by changes in climate but are current problems exacerbated by changing weather patterns and climatic conditions. For example, climate change may affect human health through the increased frequency and intensity of extreme weather events, which are drivers of malnutrition and can directly impact health. Rising temperature will affect a pathogen’s life cycle and range, which will affect the rate of infection, especially for vector borne disease. Therefore, changes in climate affect the average weather conditions to which we are accustomed. These changes may result in multiple threats to human health and welfare. It can be viewed that the overall balance of effects from climate change on health globally is likely to be negative. The adverse potential impacts of climate on health can either be direct or indirect. If the health of a population is to be sustained, requires clean air, safe water, adequate food, tolerable temperature stable climate and high level of biodiversity (according to WHO, intergovernmental panel on climate change “IPCC” 2007). Globally climate change is expected to alter temperature, air movements, and precipitation in various ways and varying degree and this will have diverse consequences on human health, economic health and ecosystem health. Climate change offers various health consequences and it is rarely possible to separate climatic and socio-economic effects on any specific population. Population of concern who are at a greater risk of experiencing the health impact of climate change includes; the poor, children, the elderly, those already in poor health state, the disabled and the indigenous population. The effects of climate change will lead to increased frequency and intensity of extreme weather events such as heat-waves, floods, and droughts, these events are drivers of malnutrition, change in pattern of disease distribution, physical injuries, loss of lives and properties, migration ,mental disorders etc, rising temperature will affect pathogen life cycles and range thus affecting the rate of infection especially for vector borne disease such as malaria, Lyme disease, west Nile virus ,dengue fever, yellow fever, Leishmaniasis, and Trypanosomiasis. An increase in global mean temperature will also alter heat and cold related death rates. Heat related disease include; heat exhaustion, cramps, mild heat oedema, heat syncope (fainting) and heat stroke. It can also exacerbate cardiorespiratory disease such as Asthmatic attack due to poor air quality etc. while there might be some positive benefits, such as a reduction in cold-related deaths in some temperate regions, overall balance of effect on health globally is likely to be negative. Impacts of climate change on health can be classified as direct and indirect impacts. The direct impacts affect human biology and include injury, morbidity and mortality cause by climate change extreme weather events( such as floods, droughts and cyclones), thermal stress (heat waves and cold periods), skin and eye damage as a result of ultra-violet light and cardiorespiratory diseases directly related to changes in temperature and air quality. However most impacts of climate change are indirect, such impacts affect non-human biogeochemical systems and may include malnutrition (as a result climate crop losses), reduced quality and quantity of water, air and changes in the life cycle and range of pathogens. Potential indirect health effects of climate on the health of a population occur predominantly through non-human biology or biochemical systems, and its include changes in crop yields, in the geographical range and distribution of infectious diseases and their methods of transport and in social pressure arising from changes in rainfall and temperature. In addition to the impacts that climate change has on food and water security, it ultimately places additional pressure on the already inadequate human support system. In detail, environmental factors are one of the main determinants of health and therefore any alteration in the environment as does climate change will offer health consequences. The health consequences depend on the extent to which the alteration occurs. These health consequences / impacts can be either direct or indirect. The indirect impacts include; Malnutrition which occurs as a result of deficiencies in balanced diet which have major impact on physical and mental health on a population. Malnutrition has lasting and detrimental health consequences often limiting physical and intellectual development particularly of those who are affected as infants or young children. It can also increase ones susceptibility to acquiring and dying from infectious disease. Climate change is expected to affect availability and affordability of food. Communicable Diseases; results from infection by pathogens such as protozoa, viruses, fungi, and parasites. They are transmitted by physical contact with infected human, vector organisms or with contaminated substances (water, food, objects and air.) climate change is expected to affect the life cycles and mood of transmission of many infectious disease. The ability of pathogen to spread is affected by its ability to mature and replicate and this is greatly influenced by environmental factors such as temperature and moisture availability. These climatic factors may also increase the survivability and density of vectors in some areas and therefore increase the likelihood of certain disease thresholds. Environment has a dominant influence on the diversity of pathogens in a region and this diversity is influenced by the human population size and density, age of settlement and the population disease control effects. Note; change in climate will impacts disease distribution, the rate of contagion, and transmission season with different level of intensity depending on the region ,the carrier, the disease and the mitigation strategy. Common communicable diseases whose transmission is influenced by climate change include; Neglected Tropical Diseases (NTDs) whose prevalence is influenced by factors such as flooding, irrigation, and climate change. Other factors include; population displacement, urbanization, extreme weather events, and air pollution. NTDs incudes; hookworms, ascariasis, schistosomiasis, lymphatic filariasis, onchocerciasis, human Africa trypanosomiasis, leishmaniasis, etc. given the connection that communicable disease have with water and other organisms, climate change is likely to lead to an increase in the range and seasonal duration of suitable conditions for communicable pathogens to survive and hence result in the spreading of communicable disease. Water Borne Disease; water is often connected to disease spread due to its role in the life cycle of vectors or its direct effect on the health of people. Alteration of the water cycle by climate change will affect water distribution worldwide. Water availability and quality are affected in various parts of the world posing a threat to human population. Spread of water-borne disease after climate change related extreme weather events (including floods, and heavy rainfall) or abnormally warm seasons (including long warm period and growing season) is expected to be high especially in vulnerable nations. Droughts may also cause increases in communicable disease as reduced river flow results in increase pathogen loading. Examples of water borne disease includes; diarrhea, cholera etc. Vector Borne Disease; climate change have a major influence on vector borne disease epidemiology. They may be transmitted by humans, by contaminated arthropods (i.e. flies, mosquitoes, ticks, sands flies, and lice), and animals (typically mammals such as rats, and less often birds. Vector borne disease includes; malaria, dengue fever, west Nile virus, yellow fever, leishmaniosis and trypanosomiasis etc. Three of the key components that determine the occurrences of vector-borne disease are; occurrence, environment, resilience. Temperature changes affect vector borne diseases by the combined effects of changing temperature and precipitation and may lead to a more suitable event for the spread of vector-borne disease and emergence of new ones. It can also influence reproductive cycles and behaviours. Frequency mostly rises with temperature and atmospheric CO2 content. In general higher ambient temperature up to a maximum shortens the viral incubation period and breeding cycle in vectors. Other communicable diseases whose spread is thought to be influenced by climate change include; Meningitis which is an air borne disease spread by respiratory droplets or saliva. It is most often in years of severe dryness and drought and in dust laden environment. HIV/AIDS patients are at greater risk due to their immune-deficient state. Climate change has impact on disease patterns. It will also impact the occurrence of opportunistic infections. Urbanization cause by climate related disasters will also increase risk due to increase population in a particular area and lack of job opportunities. According to the Social Status, disadvantaged groups have poorer survival chances and die at a younger age than more favoured groups. Life expectancy in developed countries is higher than in developing nations. As a result of climate change, forced migration can occur. Some causes of migration related to climate change and health include; extreme weather events, drought, desertification, sea level rise and disruption of seasonal weather patterns that can cause disease outbreaks and malnutrition. Migrants may carry infectious disease from their place of origin to destination and once there, they may be susceptible to disease to which they have not previously been exposed. Due to lack of adaptive capacity health issues due to climate change are not just associated with poverty, but are also a cause of poverty and a major hindrance to economic development. These health issues are associated with major negative economic effects in areas where they are wide spread. Direct impacts occur predominantly through the impacts of climate variable on human biology. Main climatic environmental variables include temperature, precipitation and air quality. Health impacts are as a result of specific events such as heat waves, floods, and air quality changes. Also direct impact of climate change on health can lead to indirect ones. Better understanding of these connections can lead to appropriate adaptation and mitigation techniques that can benefit human health. Extreme weather events and their direct health impacts; forces that create drought and flood can cause secondary issues such as lack of food, adequate clean water, increase communicable and non-communicable disease. Survivals have increased risk of contracting respiratory disease, diarrhea, and other disease in the aftermath of extreme weather events due to overcrowding, limited or no access to portable water and food and exposure to chemicals and wastes. Poor drainage and storm water management in low income urban communities increase rate of infectious disease transmission. Long term impacts include increase in infectious disease and mental stress, loss of infrastructure and territory and environmentally induced migration which can lead to further increases in infectious disease. Ultraviolet radiation related cancers and disease are responsible for pre mature death from skin, eye and cardiorespiratory disease. Though small amount are beneficial to health and play an essential role in production of vitamin D. However, excessive exposure to it is associated with different types of skin cancer, sunburn, accelerated skin aging, solar keratosis, cataract and other eye disease that reduce the effectiveness of the immune system. Temperature and precipitation increase in temperature represent a significant source of potential direct climate change impacts on human health. Temperature increase can be greater than what is comfortable for a particular region and causes mortality and morbidity through thermal stress. Heat stress affects individual during extremes in intensity and or frequency. Environmental conditions can be exacerbated by human activities such as deforestation and urbanization which can lead to local temperature increases. Patients have optimum cardiovascular health issues at higher temperature. Rising temperature will be most dangerous for the poor people in developing countries and among the most vulnerable (the young, elderly, and sick). Air quality, climate change affects air quality and can lead to respiratory disorders. Air quality can be; Meteorological; (temperature, humidity, wind speed, wind direction and mixing height), Natural (ground level ozone and light catalysed air chemistry reactions, aeroallergens, forest fires and dust from dry soils), Anthropogenic : carbon based fuels for local energy, transportation and agricultural resulting in eventual deposition of air pollutants. Particulate matter is a pollutant of concern; it is a complex mixture of extremely small particles and liquid droplets. When inhaled these particles can reach the deepest region of the lungs, exposure to particulate pollutant is linked to a variety of significant health problems. Vulnerability is determined by the quality of housing, the availability of air conditioning etc. increased death among the elderly and urban poor can result. Sunlight and high temperature combined with other pollutants such as nitrogen oxides and volatile organic compounds can cause ground level ozone to increase. Grand level ozone can damage lung tissue and is especially harmful for those with asthma and other chronic lung disease. The increase of air pollutants due to climate change may also influence cardiorespiratory disease by exposing patients with pre-existing conditions to temperature extremes high enough stress to stress the cardiovascular system. The array of health impacts includes; headaches, nausea, cardiorespiratory disease and cancer. A group of medical students in Freetown, Sierra Leone have come together believing they have strong reasons that they must start to act on climate change in order to protect the health of their future patients. They are fully aware that climate change is real and as already indicated above, there are health impacts of the relationship of people with their environment. In Sierra Leone, as in other parts of the world people are already facing health impacts from climate change. Medical students will soon become practitioners upon successful completion of their courses and they will begin to face the consequences of decisions made by today’s population. If decisions about climate change made today result in increases of health problems the new doctors and medical practitioners will face the burden. Therefore, medical students need to act fast in order to help society increase their awareness on climate change and take reasonable steps to deal with their environment in the right way. Medical students have a powerful voice and they can meaningfully influence society about climate change through social and other media. They can form Action Groups and organise Road Shows for Public Health Promotion and Teachings and campaigns. They can also disseminate important information about climate change through debates and discussions. Their individual and collective actions can help to generate changes in curriculum to incorporate climate change agenda. Additionally, they can liaise with other agencies to organise ‘Green Weeks’. All these approaches will help increase society’s awareness and knowledge on climate change. They will also help medical students master necessary skills and knowledge to effectively manage climate-related illnesses for them to adequately provide healthcare in a responsible and sustainable way. In summary, it can be seen that climate change has adverse health related issues. The effect of climate on health is inevitable and therefore medical students need to take the lead role in the fight against climate by ways of sensitizing and creating awareness to the general public about the harmful effect climate change has on health. They can also formulate possible ways to mitigate and adapt to changes caused by climate change as this can be possible solution to climate change impact on health. About the author Peter Mac Jajua attended the Beckyln Nursery and Preparatory School where he sat to the National Primary School Examination (NPSE). After which he proceeded to the Royal Beckyln Academy and sat to both The Basic Education Certificate Examination (BECE) and the West Africa Senior Secondary School Examination (WASSCE) in 2008 and 2011 respectively. Peter is presently a 4th year Medical Student at the College of Medicine and Allied Health Sciences University of Sierra Leone where he is pursuing a MBChB degree. He is also a member of the Sierra Leone Medical Student Association (SLEMSA).