The era of urbanisation and industrialisation have lead to the dramatic change in the climate of the planet Earth. The research on climate change and the associated health effects have been studied over a number of years, but the actual effect of climate change on public health is still not clear. The failure to predict the local effects of global warming leads to this uncertainty. Even if we might be familiar with future climate changes, the uncertainty regarding its impact on human health still exist (Hunter, 2003).
Over the years, the greenhouse gas content of the atmosphere is altered by human activity. This resulted in global warming. The major effect of it is seen in the Greater Himalayas located in India. The temperature at high elevations increased three times more than the global average increase in temperature. As per Intergovernmental Panel on Climate Change (IPCC), average mean annual warming will be 3 degree Celsius by 2050 and 5 degree Celsius in the 2080s over the Asian continent (Hunter, 2003). The Greater Himalayas have had increasing and decreasing precipitation rates. Although the monsoon patterns have altered, but the picture remains unclear (Hunter, 2003). It is predicted that the number of rainy days will decrease, but the average volume of water will increase for each rainfall event (Funari, Manganelli, & Sinsi, 2012). The ocean levels have also increased since 1955 due to raised heat content in water, transfer of mass from glaciers, ice sheets and river run off (Funari et al., 2012). Therefore, climate change interfere with the water cycle and increase the frequency of extreme weather conditions such as excessive precipitation, storms, floods, and droughts (Semenza, 2009). In India, about 77 million people drink contaminated water and are therefore at a great risk of being infected with water-borne diseases. It is reported that 21% of communicable diseases are water related, among which acute diarrhoeal disease is the most common (DeNormandie & Sunita, 2002).
Intense rainfalls increase the pathogen concentration in natural water sources by over flooding sewage treatment plants, runoff from animal manure and dispersing of the industrial waste. It is expected that the fast continuous moving water, counteracts the effect of UV rays and temperature on the pathogens present in water. It increase the cases of cholera, a disease caused by Vibrio cholerae, which is common in India (Funari et al., 2012). It is caused by water or food contaminated by feces of an infected person or waters polluted with sewage (webmed). Typhoid fever, caused by Salmonella typhi, is an another water borne disease which will increase in India with the changing climate conditions. Recreational waters will be polluted by run off of contaminated flood or rainfall water. It will increase the cases of viral gastroentritis and Cryptosporidium. The oocysts of Cryptosporidium and Giardia are dislocated from soil by water and carried to new places by flood water. The turbidity of surface water also increases with heavy rainfall events. It also add more nutrients into water bodies promoting the growth of coliform and planktonic species (Hunter, 2003).
Flooding can enhance the incidents of water borne diseases such as leptospirosis, hepatitis E, diarrhoeal disease, and hepatitis A. Hepatitis virus A and B are found in drinking and recreational water (Semenza, 2009). Stagnant water is the ideal site for mosquito breeding, this increases the cases of vector borne diseases such malaria, dengue, west nile fever, and chikungunya fever Japanese encephalitis, kala-azar, and filariasis (Bush et al., 2011). Deforestation, vegetation clearance, and irrigation form open water pools, favouring the growth of mosquitoes. Indeed, rainfall accounts for 45 per cent of variation in malaria transmission (Dhara et al., 2013).
parasitic diseases such as leishmaniasis, lymphatic filariasis and onchocerciasis (Dhara, Schramm, & Luber, 2013).
In droughts, the volume and surface area of water shrinks. There is no or reduced river flow, contributing to the increased effluent concentration, posing more stress on water treatment plants. Few stagnant water sites also increase the density of mosquitoes in that particular area, causing more vector borne diseases (Dhara et al., 2013).
Due to global warming, the number of frozen days decrease, which help the oocysts of giardia and cryptosporidium survive the winters. Temperature increase is expected to threat the water quality and increase cholera cases (Funari, 2012). This also influence the vector borne diseases. The increase in warmer days, allows the early maturation of the mosquito and also provide long period of breeding (Dhara et al., 2013). In India, 65% of malaria cases are reported from Orissa, Jharkhand, Madya Pradesh, Chattsgarh, West Bengal, and the North East. (Bush et al., 2011)
The death rate in India is very high due to water borne diseases, killing 1600 people every day (DeNormandie & Sunita, 2002). The majority of deaths occur due to acute diarrhoeal disease. The death toll will increase in future as the climate is changing. Poor health of the population hinders the development of the country. There is poor quality of life. The risk becomes even higher when there will be introduction of resistant stains in water (Semenza, 2009). The resistance could be to medicine, increased temperature and water treatment plants. Hepatitis A and E are also the factors of concern. The situation can be improved if the government implement appropriate policies. They must emphasize on reforestation. It will help to control the temperature and reduce water run offs. Parks and rooftop gardens are helpful in urban or industrial areas to combat the climate change.
Industrial waste must be reduced by limiting the waste amount and the working hours of industries. Improvements must be made in environmental monitoring and surveillance systems. The disease outbreaks can be prevented by educating the people about the disease and its preventive measures. Appropriate steps should be taken to improve sanitation, malnutrition and supply of clean drinking water. The health care provider must be accessible to all especially in remote areas and more susceptible areas. Improvements must be made in disease reporting, surveillance and infrastructure.