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Water Based Infections

Water is essential for human life and survival.  Clean water is a fundamental premise of public health, and without it humans have more infectious diseases and shorter lifespans.  About 20% of the world's population does not have access to clean water and 30% do not have access to sanitation.  Contaminated water leads to the second-highest cause of death in children.

 

Waterborne pathogens including viruses, parasites and bacteria pose the greatest water related threat to human health by causing infectious diseases.

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Water Based Infections Background Information

Our health, and the health of our water are tied to each other. Learn more about what's important and what you should know. 

How does water relate to health?

IMG_4039.HEIC

Water is essential for human life and survival. Clean water is a fundamental premise of public health, and without it humans have more infectious diseases and shorter lifespans. About 20% of the world's population does not have access to clean water and 30% do not have access to sanitation. Contaminated water leads to the second-highest cause of death in children. Waterborne pathogens including viruses, parasites and bacteria pose the greatest water related threat to human health by causing infectious diseases.

Why is water so abundant, yet scarce?

Though most of our planet is covered in water, only 3% is freshwater and less than 1% of earth’s water is available to drink. We use this finite amount for drinking, cooking, sanitation, agriculture and industry. Agriculture currently uses 70% of this water and pollution from industrial waste and sewage often contaminates other drinkable surface water. This competition for one resource leads to water scarcity in many parts of the world. Water scarcity leads to conflict, worse sanitary conditions, and decreased food production.

How does climate change affect access to clean water?

Certain aspects of a changing climate affect water security around the world.  As temperatures rise this leads to melting glaciers which reduces reservoirs of water fed by those glaciers.  Sea-level rising leads to contamination of coastal freshwater with saltwater.  Rain pattern shifts lead to more droughts and floods and less dependable water sources.  Greater seasonal rain variability creates difficulty with flood control and reservoir planning.  These frequent and more intense storms run the risk of pollutants mixing with freshwater, decreasing drinkable surface water.  Even surface water temperature increases lead to growth of algae, decreased oxygen content and decreased ability of the water ecosystem to keep itself clean.

What types of waterborne pathogens exist?

Bacteria:  Campylobacter, Vibrio, E. Coli, Shigella and Salmonella are common bacteria that are mainly transmitted by ingesting contaminated water from flooding/rainfall events leading to sewage/agricultural overflows or other exposures seen in poor sanitation conditions- refugee or military camps.  These cause watery diarrhea and abdominal pain that can dehydrate people to the point where their kidneys shut down.  

 

Viruses:  Norovirus, Hepatitis A, and rotavirus produce similar symptoms of severe dehydration from diarrhea and vomiting.  Norovirus is linked to flooding and heavy rainfall events and is the leading cause of vomiting and diarrheal outbreaks worldwide.  During Hurricane Katrina 12,000 people relocated to Houston tested positive for norovirus and the transmission to first responders was high as well.  

 

Parasites:  Helminths (worms) and protozoa are the two major classes of waterborne disease to humans.  These produce similar symptoms as the viruses and bacteria and are spread the same way.  The two main protozoa are:

  • Cryptosporidium is the most common partly due to its resistance to chlorination. 

  • Giardia, also known as beaver fever, is seen from sewage contamination

 

Worms infect 25% of the world's population at any time and can cause lung disease and chronic inflammation.

  • Ascariasis (roundworm)  infects 1.5 billion people worldwide

  • Strongyloides (threadworm) in immunocompromised people can cause a 70% death rate.

  • Trichuris (whipworm) infects 25% of world's population, many may be asymptomatic

How are algal blooms related to climate change?

Image by Liz Harrell

Algae are water based organisms that do not have the unique structure of plant cells.  They are vital to the entire food chain but when algae grows beyond their normal amount harm comes to the ecosystem.  These harmful algal blooms come from unchecked growth secondary to increasing water temperatures, agricultural fertilizer runoff, carbon dioxide in the atmosphere and extreme weather events.  Harmful algal blooms are occurring more frequently and in more parts of the ocean in our recorded history.

Image by Mihály Köles

How do algal blooms affect human health?

Harmful algal blooms increase the number of algae in an environment that are normally present.  Some of these organisms include cyanobacteria, dinoflagellates of the “red tides” and diatoms, all of which produce toxins.  In normal numbers in water they do not cause many issues, but when the numbers of algae explode, the toxins increase as well.  Humans can be affected by these toxins by consumption, swimming in the water or even inhaling some of the aerosolized Brevetoxins of a red tide.  Many of these toxins affect the nervous system resulting in weakness, twitching and eventually paralysis.  The Brevetoxins can cause spasms of the airways leading to asthma-like symptoms.   Ciguatera poisoning is caused by eating reef fish which consume dinoflagellates as part of their diet, this leads to vomiting, diarrhea, pain and neurologic symptoms including paralysis.  There are even links to progressive body paralysis known as Lou Gehrig’s disease (amyotrophic lateral sclerosis) to high cyanobacteria exposures.

What can we do to prevent exposure?

Working on solutions to climate change can help decrease the energy in the environment leading to severe storms, flooding and drought that causes these diseases. 

 

Valuing clean drinking water and renewing our water tables in Arizona will help decrease stormwater runoff and increase resilience to drought.  We can all work on rainwater capturing techniques in our neighborhood to decrease runoff and flooding events, while increasing our water table and decreasing our water insecurity.  During flood events or contact with contaminated water ensure use of soap and clean water before eating and after using the bathroom.

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