Climate change is increasingly being implicated in species' range shifts throughout the world, including those of important vector and reservoir species for infectious diseases. Intergovernmental Panel on Climate Change predicted that the mean global temperature would increase by between 1.4C and 5.8C over the period 1990 to 2100. Recent investigations attribute more than 150,000 deaths per year and a global disease burden of approximately 5 million DALYs annually to climate change. It is well known that the impact of climate change is on physical and biological systems, including human health. An area that has received particular attention is the potential impact of global warming on shifts in the spatio-temporal distribution of disease vectors, and hence the frequency and transmission dynamics of vector-borne diseases. Vectors, pathogens (parasites), and hosts survive and reproduce within certain optimal climatic conditions. Changes in climate will alter the transmission of vector-borne diseases in different ways, such as changing the survival and reproduction rate of the vector and of the pathogen (parasite), as well as changing vector activities.
Public health officials often use the term tropical diseases to refer collectively to a list of infectious diseases that are found primarily in developing countries. These include malaria, schistosomiasis, dengue, trypanosomiasis, leprosy, cholera, and leishmaniasis, among others. Many of these diseases are spread by insect vectors, and all of them disproportionately affect the world's poor. Malaria is the most severe of these as stated by World Health Organization, but other diseases, less well known and sometimes described as neglected and also imposes grave burdens on people living in the tropics. The World Health Organization estimates that neglected tropical diseases affect over one billion people each year and cause about 570,000 deaths annually. For example, some 200 million people are currently infected with schistosomiasis, a parasite that is transmitted through poor sanitation. Perhaps 50 million cases of dengue occur each year, of which 500,000 lead to devastating hemorrhagic fever, with 22,000 resulting deaths. More than 1.5 billion of the world's poorest people are affected by a range of bacterial and worm based diseases including trachoma, river blindness and lymphatic filariasis. They are just some of so-called neglected tropical diseases, which are diseases of poverty. But despite the numbers they affect, and their health and social consequences, these diseases attract less than one per cent of the total health funding for the developing world.
The potential impact of global warming on the transmission of the neglected tropical diseases has received insufficient attention from researchers and different organization. Most studies on the impact of global warming on the transmission of tropical diseases have focused on malaria but very few studies have been carried out regarding the neglected tropical diseases. The Intergovernmental Panel on Climate Change (IPCC) has specially investigated the changing burdens of infectious disease that may result from climate change. One IPCC background report notes that: Climate plays a dominant role in determining the distribution and abundance of insects and tick species directly, through its effects on vector and parasite development, and indirectly through its effects on host plants and animals and land-use changes. Therefore, it is anticipated that climate change will have an effect on the geographical range and seasonal activity of vector species and, potentially, disease transmission.
Global attention to infectious disease is primarily focused on HIV/AIDS, tuberculosis and malaria; the big three, as they are called, were responsible for over five million deaths in 2007 and are responsible for 39% of all deaths attributed to infectious disease. Unfortunately, this attention has not extended to a group of parasitic and microbial diseases called the neglected tropical diseases (NTDs). These diseases are largely overlooked, due to their low mortality rate and the poverty of their sufferers. Neglected tropical diseases affect the poorest individuals. Over 70% of the affected areas have low to lower-middle income economies. They thrive under poor sanitary conditions, where clean water and food are unavailable and where insect vectors are abundant. Women, children and those geographically isolated from health care are particularly susceptible. Those in conflict-ridden areas are also particularly susceptible, due to the disruption of any health-care infrastructure. Aside from thriving in poverty, the NTDs are also said to be poverty-promoting conditions, as they reduce worker productivity and impair childhood development, and, consequently, the future earning abilities of those children. The resulting economic loss tends to worsen already impoverished conditions.
Bangladesh is highly vulnerable to climate change and its high population density. Floods and cyclones are some of the major challenges that the country faces resulting in the greatest economic and human losses to the country. Higher temperatures including more extreme weather events and sea level rise are already evident in Bangladesh. One estimate is that the average increase in temperature in Bangladesh would be 1.3C and 2.6C by the year 2030 and 2075 respectively with respect to the base year 1990. Global warming will increase the intensity of southwest monsoon, which will, in turn, bring about catastrophic ravages like floods and have far reaching consequences on health. During and after floods, the water borne diseases increase due to heavy contamination of the surface water. Thus climate change could cause floods, break-down of sanitation system, and more water and food-borne diseases like soil-transmitted helminthiasis (STH), cholera, and other diarrhoeal diseases. Bangladesh may be one of the worst hit countries of the world due to a predicted rise in sea level. The increase in salinity in underground water will affect the availability of fresh safe water. As a result, people will be more inclined to use unsafe, contaminated surface water and will contact various water borne infectious diseases like cholera and other diarrhoeal diseases and STH. Incidence of vector-borne diseases like malaria, filaria, leishmania and dengue are likely to increase as a result climate change in this region. This may increase the human contact with the vectors responsible for spread of diseases like malaria, filaria, leishmania and dengue. Though the surveillance system is very weak with gross under reporting, 13 districts of Bangladesh are known to be endemic for malaria, 34 for filariasis and 45 for visceral leishmaniasis (VL). Dengue has been detected in all six divisional headquarters of Bangladesh whereas STH affects our population throughout the country. Filariasis is a parasitic disease which is believed to have infected about 20 million people; 10 million are with various forms of disability, leaving another 70 million at risk of infection. The incidence of visceral leishmaniasis on the other hand is estimated to be about 12,000 per year with about 65 million people at risk of contracting the disease. Some reports claimed a death rate of more than 10% in patients suffering from VL. About 70000 to 80000 malaria cases and 300 to 700 death cases are reported yearly.
The impact of climate changes on neglected tropical diseases is itself neglected. There is an urgent need for researchers and organizations to investigate further the potential impact of climate changes on the transmission of neglected tropical diseases. The findings of such research are required so that populations might be able to adapt or, if necessary, migrate to overcome increased risks for transmission of neglected tropical diseases caused by climate changes.

Khalid Md. Bahauddin
Fellow (Japan), Environment; Member, Bangladesh Society of Environmental Scientist
and Bangladesh Solar Energy Society.

E-mail: Khalid_mbuddin@yahoo.com This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Mobile: +88 01670102423

The number of people on Earth, where they live, and how they live all affect the condition of the environment. Changes in environmental conditions, in turn, can affect human health and well-being. Human demographic dynamics, such as the size, growth, distribution, age composition, and migration of populations, are among the many factors that can lead to environmental change. The precise impact of a given change depends on the interplay among all these factors, but it is clear that demographic change can affect the environment.HIV/AIDS is one of those diseases which can change on demographic pattern as well as can change various types of Environment. Approximately 39.5 million people around the world were living with HIV/AIDS in 2006. Of these, almost two thirds were in sub-Saharan Africa. The same year, an estimated 2.9 million AIDS-related deaths occurred globally. The number of people living with HIV continues to rise around the world especially in Africa, parts of Eastern Europe, the Caribbean, and South, Southeast, Central and East Asia, with prime age adults being affected most (UNAIDS 2006a). HIV/AIDS has rapidly become one of the major problems, particularly in poor countries. It is shown that it is primarily increasing difficulties in making sustainable use of natural resources when time, energy and money must be used to relieve the effects of ill health and when labour is tragically lost. At the same time various forms of environmental degradation affect the general health status of people and increase their vulnerability. When HIV/AIDS is added to the list, there is a danger that people cannot make a living any more.

CLIMATE change refers to any significant change in measures of climate. Potential effects of this climate change are likely to include more variable weather, stronger and longer heat waves, more frequent heavy precipitation events, more frequent and severe droughts, extreme weather events such as flooding and tropical cyclones, rises in sea level, and increased air pollution. Other effects may result from ecosystem shifting and disruption.Climate change is an emerging risk factor for human health. According to the third assessment report of the Intergovernmental Panel on Climate Change, Climate change can affect human health directly (e.g. impacts of thermal stress, death/injury in floods and storms) and indirectly through changes in the ranges of disease vectors, waterborne pathogens, water quality, air quality, and food availability and quality. The actual health impacts will be strongly influenced by local environmental conditions and socio-economic circumstances, and by the range of social, institutional, technological, and behavioural adaptations taken to reduce the full range of threats to health.Broadly, a change in climatic conditions can have three kinds of health impacts: those that are relatively direct, usually caused by weather extremes; the health consequences of various processes of environmental change and ecological disruption that occur in response to climate change; and the diverse health consequences traumatic, infectious, nutritional, psychological and other that occur in demoralised and displaced populations in the wake of climate-induced economic dislocation, environmental decline, and conflict situations.Climatic changes over recent decades have probably already affected some health outcomes. The World Health Organisation estimated, in its World Health Report 2002, that climate change was estimated to be responsible in 2000 for approximately 2.4 per cent of worldwide diarrhoea, and 6 per cent of malaria in some middle-income countries. Marked short-term fluctuations in weather can cause acute adverse health effects: extremes of both heat and cold can cause potentially fatal illnesses, e.g. heat stress or hypothermia, as well as increasing death rates from heart and respiratory diseases. In cities, stagnant weather conditions can trap both warm air and air pollutants leading to smog episodes with significant health impacts. These effects can be significant. Abnormally high temperatures in Europe in the summer of 2003 were associated with at least 27,000 more deaths than the equivalent period in previous years. Other weather extremes, such as heavy rains, floods, and hurricanes, also have severe impacts on health.Approximately 600,000 deaths occurred worldwide as a result of weather-related natural disasters in the 1990s; and some 95 per cent of these were in poor countries. To a large extent, a changing climate is likely to affect public health which depends on safe drinking water, sufficient food, secure shelter, and good social conditions. Reviews of the likely impacts of climate change by the IPCC suggest that a warming climate is likely to bring some localised benefits but overall the health effects of a rapidly changing climate are likely to be overwhelmingly negative, particularly in the poorest communities, which have contributed least to greenhouse gas emissions.Recent analyses show that human-induced climate change significantly increased the likelihood of the European summer heat wave of 2003; more variable precipitation patterns are likely to compromise the supply of freshwater, increasing risks of water-borne disease. Rising temperatures and variable precipitation are likely to decrease the production of staple foods in many of the poorest regions, increasing risks of malnutrition. Rising sea levels increase the risk of coastal flooding, and may necessitate population displacement. More than half of the worlds population now lives within 60km of the sea. Some of the most vulnerable regions are the Nile delta in Egypt, the Ganges-Brahmaputra delta in Bangladesh, and many small islands, such as the Maldives. Changes in climate are likely to lengthen the transmission seasons of important vector-borne diseases, and to alter their geographic range, potentially bringing them to regions which lack either population immunity or a strong public health infrastructure.Heat exposure has a range of health effects, from mild heat rashes to deadly heat stroke. Heat exposure can also worsen several chronic diseases, including cardiovascular and respiratory disease. The results can be severe and result in both increased illness and death. Heat also increases ground-level ozone concentrations, causing direct lung injury and increasing the severity of respiratory diseases such as asthma and chronic obstructive pulmonary disease. The direct effects of extreme weather events include drowning from floods, injuries from floods, and structural collapse. Potential indirect effects include aggravation of chronic diseases due to interruptions in healthcare service, significant mental health concerns both from interrupted care and geographic displacement, and socioeconomic disruption resulting from population displacement and infrastructure loss.Air quality is highly affected by weather and climate conditions. In turn, certain aspects of air quality are known to affect health. Ozone causes direct, reversible lung injury; increases premature mortality; worsens respiratory diseases such as asthma and chronic obstructive pulmonary disease; and may cause chronic lung damage. Storms and extreme precipitation events have several direct health effects. Extreme precipitation events are associated with outbreaks of gastrointestinal disease.Heat waves are already the most deadly weather-related exposure in the US. Studies suggest that, if current emissions hold steady, excess heat-related deaths in the US could go up from an average of about 700 each year currently, to between 3,000 and 5,000 per year by 2050. Climate is one of many variables known to affect the rates of vector-borne and zoonotic diseases such as vector mosquito species, which spread malaria and viral diseases such as dengue and yellow fever. Malaria, today, is mostly confined to tropical and subtropical regions. The diseases sensitivity to climate is illustrated by desert and highland border areas where higher temperatures and rainfall associated with El Nio may increase transmission of malaria. Dengue is the most important arboviral disease of humans particularly in urban settings. Between 1970 and 1995, the annual number of dengue epidemics in the South Pacific was positively correlated with La Nia conditions (i.e. warmer and wetter). In the tropics diarrhoeal diseases typically peak during the rainy season. Both floods and droughts increase the risk of diarrhoeal diseases. Major causes of diarrhoea linked to heavy rainfall and contaminated water supplies are: cholera, cryptosporidium, E.coliinfection, giardia, shigella, typhoid, and viruses such as hepatitis A.Various analyses have shown that health impacts are often the largest single contributor to the costs of environmental damages. The governments health authorities should undertake a comprehensive evaluation of the possible health implications of such changes and need to determine priorities for planning and decision-making. The health sector should be involved jointly with agricultural, meteorological, environmental, and planning agencies to ensure that health considerations are given adequate weight. But not only for these individual awareness is also needed such as lifestyle change, behavioural change, efficient use of energy, etc.

In search of safe waterPEOPLE need clean water and sanitation to maintain their health. Water also sustains ecological systems and provides an input into the production systems that maintain livelihoods. Water security is an integral part of a broader conception of human security.In broad terms, water security means ensuring that every person has access to enough safe water to lead a healthy life, while maintaining the ecological systems that provide water and also depend on water.When water security is absent, people suffer from poor health and the disruption of livelihoods. Some 2.6 billion people -- half the developing world's population -- do not have access to basic sanitation, and underreporting means that these figures understate the problem. "Not having access" to water and sanitation is a polite euphemism for a form of deprivation that threatens life, destroys opportunity and undermines human dignity.Deprivation of water and sanitation has many bad effects. Some of those are:-Some 1.8 million child deaths each year are a result of diarrhoea -- 4,900 deaths everyday, or an under-five population equal to that of London and New York combined. Deaths from diarrhoea in 2004 were some six times greater than the average annual deaths in armed conflicts for the 1990s. Together, unclean water and poor sanitation are the second biggest killers of children.-The loss of 443 million school days each year from water-related illness.-Close to half of all people in developing countries suffering at any given time from a health problem caused by water and sanitation deficits.-Millions of women spending several hours a day collecting water.-Water insecurity inflicts millions of people with illness, and lost educational opportunities in childhood leading to poverty in adulthood.At the beginning of the "Water for Life" decade, 1.1 billion people did not have access to clean drinking water, 84% of who lived in rural areas. 2.6 billion people, more than 40% of the world population, do not use a toilet.In 2004, more than three out of every five rural people did not have access to basic sanitation facility. If the current trend persists, nearly 1.7 billion rural dwellers will still not have access to improved sanitation by 2015.Bangladesh has a population of about 144 million, of whom 40% are under the poverty line. An estimate puts the total population at 181 million by 2025, with 41% living in the urban areas -- nearly half of them will be poor and without services.In Bangladesh, up to 40% of overall morbidity is due to water and sanitation related disease in some communities. In the year 2000, 12.1% DALYS were lost due to diarrhoeal diseases, and 90% of these were attributable to environmental causes of which 65% could be averted through improvement in water supply, sanitation (latrines, drainage, rubbish disposal) and hygiene awareness. Diarrhoeal diseases, due to water pollution, lack of hygiene, and poor sanitation account for 11% of total deaths in Bangladesh.The most alarming fact is that hygiene-related diseases costs the country, Tk. 500 crore per year for treatment alone. According to the Dhaka Water and Sewerage Authorities, the groundwater table -- the source of drinking water for one-third of this city's 10 million people -- has become contaminated with harmful bacteria.Bangladesh is grappling with the largest mass poisoning of a population in history because groundwater used for drinking has been contaminated with naturally occurring inorganic arsenic. It is estimated that of the 125 million inhabitants of Bangladesh between 35 million and 77 million are at risk of drinking contaminated water.Arsenic in groundwater poses a great challenge to the water supply in the country. Since its detection in 1993, various organisations have been screening tube wells for arsenic contamination. The most contaminated areas lie in the districts of Chandpur, Comilla, Noakhali, Munshiganj, Faridpur, Madaripur, Gopalganj, Shariatpur and Satkhira.Excessive levels have also been found in other regions. Arsenic-contaminated drinking water is a public health emergency. Exposure to arsenic from drinking water increases the risk of skin, lung and bladder cancer.WHO has predicted that in most of the southern part of Bangladesh almost 1 in every 10 adult deaths in the next decade will be a result of cancer triggered by arsenic poisoning. From the experience of Taiwan it has been forecasted that almost two million of people are at risk of developing cancer in the coming decades.Each day of continued exposure increases the risk of morbidity and death. Unlike other major health problems experienced in Bangladesh, arsenic-caused diseases can be eradicated at relatively low cost.Safe water and sanitation are basic necessities, so we must ensure their availability, not only for the present but also for the future.http://www.thedailystar.net/story.php?nid=47693