Climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

is expected to increase the severity of most meteorological conditions which will in turn increase the

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

area and seasonal duration of

waterborne diseases Waterborne diseases are conditions (meaning adverse effects on human health, such as death, disability, illness or disorders) caused by pathogenic micro-organisms that are transmitted in water. These diseases can be spread while bathing, washing ...

. Climate change, and its effects are already being seen around the globe in warmer water,

drought A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

, higher rainfall, and

flooding A flood is an overflow of water ( or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are an area of study of the discipline hydrolog ...

. Related changes in

are already being documented globally and are expected to increase, not only in developing countries but also in already developed countries. Extreme precipitation, storm surges, and flooding are already on the rise due to climate change. These present a large risk to current system capacities and could lead to disruption or failure in the infrastructure. The current trend shows a positive correlation between waterborne diseases and meteorological conditions changing due to climate change.

Changes in precipitation and water cycle

Climate change is forecast to have substantial effects on the

water cycle The water cycle, also known as the hydrologic cycle or the hydrological cycle, is a biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth. The mass of water on Earth remains fairly cons ...

, with an increase in both frequency and intensity of droughts and heavy precipitation events. Heavy precipitation events are expected to also increase flood events in the future. Precipitation events are expected to increase in intensity, but lessen in amount and duration. This will cause an increase in heavy flooding events during the precipitation event and droughts in-between. There is also an expected increased contrast between the wet and dry regions and seasons globally. Due to the increasing temperature and change in precipitation events waterborne diseases are among the primary health impacts expected from the changing climate.

Water-borne diseases

Climate change is expected to have a major impact on

. These are diseases caused by a pathogen transmitted through water. The symptoms of waterborne diseases typically include diarrhea, fever and other flu-like symptoms, neurological disorders, and liver damage. Changes in climate have a large effect on the distribution of microbial species. These communities are very complex and can be extremely sensitive to external climate stimuli. One of the most commonly transmitted waterborne disease categories are the

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...

diseases. These diseases are transmitted through unsafe drinking water or recreational water contact. Diarrheal diseases account for 10-12% of deaths in children under five, as the second leading cause of death in children this age. They are also the second leading cause of death in low and middle income countries. Diarrhea diseases account for an estimated 1.4–1.9 million deaths worldwide. There is a very high risk of increase in waterborne diseases worldwide due to climate change, according to the

Intergovernmental Panel on Climate Change The Intergovernmental Panel on Climate Change (IPCC) is an intergovernmental body of the United Nations. Its job is to advance scientific knowledge about climate change caused by human activities. The World Meteorological Organization (WMO) a ...

(IPCC).

Climate change effects on waterborne diseases

Temperature

The average global

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

is rising and is expected to continue to rise at a rapid rate. High temperatures can alter the survival, replication, and virulence of a pathogen. Higher temperatures can also increase the pathogen yields in animal reservoirs. During the warmer summer months an increase in yield of bacteria from drinking water delivery systems has been recorded. During times of warmer temperatures water consumption rates are also typically higher. These together increase the probability of pathogen ingestion and infection. With the known increase in global temperature averages and the positive association between temperature and waterborne diseases, especially diarrheal diseases, the number of waterborne outbreaks will most likely increase. In hotter regions, especially ones with low water supply already, there will be an increase in amount of runoff water collected and reused. This could lead to an increase in consumption of contaminated water. With an increase in not only temperature, but also higher nutrient concentrations due to runoff there will be an increase in

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

l blooms.

Rainfall and flooding

Climate change has been modeled to increase the intensity of

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

events leading to an increase in major flooding events. Studies have shown an increase in gastrointestinal and diarrheal diseases associated with major precipitation events and increased temperature. Due to heavy rainfall events leading to increased runoff pathogens become mobilized and compromise water and sanitation infrastructure. Flooding can displace populations and can lead to a variety of impacts on health. Pathogens can come from a variety of locations including human and/ or animal excrement that are present in soils or fertilizer runoff from farms. Heavy rainfall leads to the resuspension of pathogens in soils leading to the contamination of groundwater. The rainfall mobilizes these pathogens and transports them into waterways making it more likely for individuals to be exposed to the pathogen. Heavy rainfall leads to an overflow of the storm drains, which are sometimes combined with the sewage system. In these areas contaminated water can be mixed into the rivers. There are also reports of floodwaters leading to the contamination of sources of underground drinking water. Between 20-40% of outbreaks including both ground and surface water were associated with extreme precipitation events. Typically flooding is associated as a risk of increased waterborne diseases more so in developing countries, but can affect the developed world in places where water sources are already compromised. In the United States there are as many as 900,000 cases and 900 deaths annually from waterborne diseases that have been linked to both droughts and flooding.

Droughts

The amount of water within the global water cycle is constant, the amount of water evaporated from waterbodies has to come back down as precipitation. If climate change is causing precipitation events to increase in intensity then either the duration of the events has to be shorter, there has to be more time in between events, or both. There is also the possibility of precipitation events occurring less often in one area and becoming stronger in another. This will cause droughts in areas with less precipitation, or longer periods of time between precipitation events.

Droughts A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...

lead to an increase in sediment and contaminant levels in water bodies as water is evaporated out. This causes pathogens to concentrate in limited water supplies. Droughts will also cause more people to collect rain water and runoff, and in turn pathogens within the water increasing the risk of exposure.

Examples

Vibrio infections

In the United States approximately 80,000 people are infected and 100 die from vibriosis yearly.

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive ...

infections are caused by consuming raw or undercooked seafood, or by exposing an open wound to contaminated sea water. Vibrio infections are most likely to occur during the warm season, May through October. Vibrio illnesses are increasing worldwide, in the United States it has increased by an estimated 41% between 1996 and 2005. Vibrio infections are recently being reported where historically it did not occur. The warming climate seems to be playing a substantial role in the increase in cases and area of occurrence.

Nontuberculous mycobacteria

Nontuberculous mycobacteria Nontuberculous mycobacteria (NTM), also known as environmental mycobacteria, atypical mycobacteria and mycobacteria other than tuberculosis (MOTT), are mycobacteria which do not cause tuberculosis or leprosy (also known as Hansen's disease). NTM do ...

(NTM) is a lung disease that mainly affects people with an underlying lung disease or a weakened immune system. The organisms that cause NTM are commonly found in soil and water. Currently in the United States there are more than 86,000 people infected with NTM. Climate change causes an increase in natural disasters which cause a spread of the NTM pathogen. In the United States, states with a higher occurrence of natural disasters also show a higher prevalence of NTM infections. One study done looked at the prevalence of NTM in the United States in the years following Hurricanes IKE, Katrina, and Rita. The study found the highest prevalence of NTM occurred in places most affected by the hurricanes.

Legionella

Legionella ''Legionella'' is a genus of pathogenic gram-negative bacteria that includes the species '' L. pneumophila'', causing legionellosis (all illnesses caused by ''Legionella'') including a pneumonia-type illness called Legionnaires' disease and a mi ...

infections have flu-like symptoms and can sometimes lead to

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity ...

. It is found in water and some potting soils. Legionella is commonly transmitted through inhaling contaminated aerosols, commonly from water sprays, jets, or mists. It can also occur from aspiration of contaminate water. Legionella is known to show a seasonal pattern with a peak during the warm months in temperate regions. With climate change expected to continue to increase the global temperature average some locations will stay warm longer. This could lead to more exposure as the gardening season expands causing more exposure to potting soils and water sprayers. Longer hotter summers could also lead to an increase in the use of cooling systems, such as cooling towers. These are known as hotspots for legionella outbreaks.

References

{{reflist Effects of climate change Climate change and society Waterborne diseases Climate change and the environment