by Dr. Jaclynn Moskow
Waterborne diseases are contracted through exposure to contaminated water including drinking water, water used in food preparation, and swimming water.
They can be caused by bacteria, viruses, and parasites. Below is a partial list of waterborne disease pathogens, their microbial classification, and their resulting illnesses.
|Bacterium||Escherichia coli||E. Coli Diarrhea|
|Bacterium||Legionella pneumophila||Legionnaires’ Disease|
|Bacterium||Salmonella typhi||Typhoid fever|
|Parasite||Naegleria fowleri||Primary Amoebic Meningoencephalitis (PAM)|
|Virus||Hepatovirus A||Hepatitis A|
WHO IS MOST AFFECTED BY WATERBORNE DISEASES?
The vast majority of waterborne diseases are contracted by individuals who lack access to safe and sanitized water for drinking and personal hygiene. This problem is pervasive around the globe.
According to the World Health Organization (WHO), 2.2 billion people do not have access to safe drinking water, which equates to 1 in 3 people on the planet. Additionally, 4.2 billion people lack access to adequate sanitation facilities such as hygienic toilets. This lack of access to safe water and sanitation results in 4 billion cases of waterborne diseases annually and 3.4 million deaths.
Increasing access to clean water worldwide is the single most critical step we can take to prevent morbidity and mortality from these devastating diseases.
Symptoms of waterborne diseases are primarily gastrointestinal and include fever, nausea, vomiting, and diarrhea. 88% of all deaths that occur as a result of diarrhea can be attributed to these infections. 90% of diarrhea deaths involve children under the age of five years. Children are particularly susceptible to waterborne diseases, in part because their naive immune systems have not yet encountered most pathogens.
Another group who are at increased risk for contracting waterborne diseases is people that are immunocompromised, including individuals living with HIV/AIDS. Unfortunately, the HIV epidemic has hit hardest in areas where access to clean water is lacking.
Countries that have reported recent outbreaks of Cholera include Bangladesh, Haiti, The Democratic Republic of the Congo, Ethiopia, Somalia, and Yemen. The Democratic Republic of the Congo and Haiti have also reported recent outbreaks of Typhoid fever, as have Uganda and Pakistan.
HOW CAN TRAVELERS AVOID WATERBORNE DISEASES?
Tourists are at increased risk for contracting waterborne diseases, in part because they lack prior exposure and immunity. To avoid waterborne illnesses when traveling to an area of concern, the Centers for Disease Control and Prevention (CDC) recommends the following:
- Eat only foods that are cooked and served hot
- Avoid food that has been sitting on a buffet
- Eat raw fruits and vegetables only if you have washed them in clean water or peeled them
- Only drink beverages from factory-sealed containers
- Avoid ice – which may have been prepared from unclean water
- Only drink pasteurized milk
- Wash hands often with soap and water for 20 seconds, especially after using the bathroom and before eating
- If soap and water are not available, use a hand sanitizer that contains at least 60% alcohol
- Keep your hands away from your face and mouth
Travelers can also receive vaccines for some waterborne diseases, namely, Typhoid Fever, Hepatitis A, and Cholera. Since the efficacy of these vaccines varies, general precautions including avoidance of tap water should still be taken.
WHAT WATERBORNE DISEASES ARE SEEN IN THE DEVELOPED WORLD?
Sporadic outbreaks of several waterborne diseases are also reported in industrialized countries. A well-known example occurred in 1993 in Milwaukee, Wisconsin when over a two-week period approximately 403,000 individuals experienced a diarrheal illness. The cause was determined to be Cryptosporidium that had contaminated one of the city’s water-treatment plants. A more recent example occurred in 2019 when over 2000 residents of a small island in Norway became ill as a result of Campylobacter contaminating the local water supply.
In 2015, 31% of students at a school camp in South Korea became ill as a result of water contaminated with E. coli. There have also been outbreaks of typhoid fever in the United States. Outbreaks of waterborne disease increase after extreme weather events such as flooding caused by heavy rains and snowfall. After Hurricane Katrina, Salmonella enterica, Vibrio cholerae, and Norovirus were detected in individuals in evacuee camps.
CONTRACTING WATERBORNE DISEASES WHILE SWIMMING
Waterborne diseases can also be contracted by swimming in pools, lakes, rivers, and oceans. This includes Giardia lamblia, which is one of the most common intestinal parasites worldwide, including in the United States. Giardia lamblia can enter the body in a number of ways, including ingestion of water while swimming.
Another parasite that can be contracted while swimming is Naegleria fowleri, which is found in freshwater and often referred to in headlines as “the brain-eating amoeba.” Naegleria fowleri invades the body via the nose and travels to the brain by way of the olfactory nerve. Unlike Giardiasis, Primary Amebic Meningoencephalitis caused by Naegleria fowleri is almost always fatal. Fortunately, the condition is exceedingly rare.
Over 250 million persons suffer from Schistosomiasis – in Africa, Asia, and the Americas. Parasites enter through the skin, usually while swimming, working, or simply walking through freshwater. The parasites travel through the bloodstream, eventually lodging in the liver, urinary system, and other organs with resultant damage to tissues, or even cancer which can develop over many years.
Recreational water areas such as pools, hot tubs, and spas are also at risk of contamination by a variety of pathogens. Between 2000 and 2014, 212 reported outbreaks of Cryptosporidium were associated with recreational water facilities. Adenovirus is also known to cause outbreaks from recreational water, as is Legionella pneumophila. Legionella pneumophila is a unique waterborne pathogen in that it often must be aerosolized to cause infection. The organism is transmitted via hot tubs, showers, humidifiers, and air conditioning systems. Aerosolization allows Legionella pneumophila to enter the lungs and thus, unlike other waterborne pathogens, it can cause respiratory illness. A milder form of the disease caused by Legionella species is known as Pontiac fever, and the more severe form is known as Legionnaires’ Disease.
CAN SARS-COV-2 BE TRANSMITTED THROUGH THE WATER SUPPLY?
Fortunately, you cannot contract COVID-19 through contaminated water. Viruses may be classified as either enveloped or non-enveloped. Viruses with envelopes have an outer layer of proteins and lipids that surround their viral capsids. Non-enveloped viruses can survive for relatively long periods outside the body – and in much harsher conditions – than can enveloped viruses.
Viruses that cause waterborne diseases, such as Hepatovirus A, Norovirus, Rotavirus, and Adenovirus, are all non-enveloped. In contrast, members of the Coronaviridae (such as SARS-CoV-2) are enveloped and thus cannot be spread through the water supply.
Although we cannot contract SARS-CoV-2 from the water supply, inactive SARS-CoV-2 viral material can still be detected in the wastewater from areas with COVID-19 outbreaks. This can be useful in tracking outbreaks. In Switzerland, for example, laboratories were able to determine that a new “British variant” of SARS-CoV-2 had arrived by simply monitoring wastewater. In fact, monitoring wastewater is an emerging epidemiological tool for tracking many pathogens, including many of the waterborne diseases discussed above.
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