puricarexfiles: PATHOGENIC PROTOZOA AND AMOEBA - Drinking water supplies that depend on surface or ground water are subject to contamination by enteric waterborne pathogens. The detection of these pathogens and other indicator organisms may indicate fecal contamination of water.

Protozoa and Amoeba in

Drinking Water

Sources of protozoa and amoeba in drinking water

Drinking water supplies that depend on surface or ground water are subject to contamination by enteric waterborne pathogens.
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The detection of these pathogens (and other indicator organisms) may indicate fecal contamination of water.

These pathogens can originate from leaking sewer lines, septic systems, or improperly protected well heads that allow contaminated surface water to drain into the aquifer along the outer well casing.

Contaminated ground water represents approximately half of the waterborne disease outbreaks documented in the United States every year.

Organisms of particular concern with respect to water contamination include waterborne pathogenic human enteric viruses, such as Adenovirus, Rotavirus, Hepatitis A, and Norovirus; enteric bacteria, such as the pathogenic strain of Escherichia coli 0157:H7, Salmonella, Campylobacter, Vibrio cholerae and Shigella spp.; protozoan pathogens, such as Cryptosporidium and Giardia; and, the recently reported amoeba Naegleriafowleri.

These organisms present a human health risk to those who ingest the water. Typical symptoms associated with an infection include acute gastroenteritis, severe cramping, abdominal pain, dehydration and diarrhea.

Although all of the above mentioned organisms pose a risk to human health, viral contaminants are typically considered more of a threat to groundwater than bacterial or protozoan contaminants for two reasons.

First of all, because of the small size of viruses, they typically can be transported further into the aquifer than bacteria and can eventually reach the groundwater.

Secondly, viruses are thought to be more persistent in the environment than their bacterial counterparts and require greater disinfection procedures to render them inactive.

Cryptosporidium and Giardia

Microorganisms transmitted by the fecal-oral route are referred to as enteric pathogens because they infect the gastrointestinal tract.

cryptosporidium-oocysts

One specific group of enteric pathogens is called protozoa. All protozoa rely on water, and they are most commonly observed in freshwater and marine habitats, although some are terrestrial in moist soils and others are exclusively found in the gastrointestinal tracts of animals.

Diseases caused by protozoa that are transmitted by contaminated drinking water are considered waterborne diseases.

Common protozoa, such as Cryptosporidium and Giardia, are extremely hardy and can survive chlorine disinfection that is commonly practiced at conventional water treatment plants.
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Giardia

These organisms can enter the environment via human and animals wastes and have been found in marine water and bathing beaches in the vicinity of sewage outfall locations.

Additionally, cattle are known to harbor these organisms, and consequently agricultural landrunoff has been shown to contaminate surface water.

The pathogenic protozoan parasites, Cryptosporidium and Giardia, are significant microbial contaminants in the U.S. and have been found in surface waters and filtered drinking water supplies.

Cryptosporidium and Giardia produce environmentally resistant oocysts and cysts, respectively, which allow the parasites to survive in water for extended periods of time.

Giardia

Many waterborne outbreaks of cryptosporidiosis and giardiasis have been reported in North America.
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Increases of microbial pathogens in lakes and streams due to heavy rainfall events/flooding can lead to breeches in the treatment process and have occasionally resulted in community outbreaks of gastroenteritis.

Another source of outbreaks could be due to a breakdown in the water treatment process, such as coagulation, filtration, or disinfection.

Naegleria fowleri

Naegleria fowleri is a protozoan amoeba found in soil environments but more frequently in ground and surface waters. Because Naegleria is commonly found in warmer temperatures, states in the Southwest are particularly prone to its presence.

In a recent study in Arizona of 188 drinking water systems and individual household wells, the waterborne amoeba Naegleria fowleri was reported in 29 cases.

Biodegradable oils used to lubricate ground water pumps may act as a food source for bacteria and other organisms. Research has indicated that N. fowleri, may feed upon bacteria growing in wells, thus allowing them to persist in the environment.

Naegleria fowleri

Although it is alarming that this waterborne pathogen is currently being found in wells in warmer climates, infections occur only by immersion in the water and do not occur as a result of drinking contaminated water.

Potential health effects of protozoa and amoeba in drinking water

Cryptosporidium and Giardia have become the leading cause of gastroenteritis outbreaks associated with treated recreational water venues (e.g., swimming pools, water parks, water slides, wave pools, interactive fountains).

The availability of the first drug to combat Cryptosporidium illness has likely increased the chance that healthcare providers test for the protozoan when a patient has diarrhea.
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Additionally, improvement of Cryptosporidium tracking systems has also led to the investigation of more cases, and consequently more outbreaks have been identified.

Alternatively, Naegleria causes acute primary amoebic meningoencephalitis in infected individuals.
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According to the Centers for Disease Control (CDC), Naegleria infects people by entering the body through the nose. This can occur when people use warm freshwater or untreatedground water for activities like swimming or diving.

The amoeba travels up the nose to the brain and spinal cord where it destroys the brain tissue. Symptoms are said to mimic a hangover and include a head ache as well as stiffness of the back and neck.

Options for protozoa and amoeba in drinking water

Unlike most waterborne pathogens, such as bacteria and enteric viruses, Cryptosporidium and Giardia oocysts and cysts are very resistant to chlorine disinfection, which is commonly used to treat surface and ground waters.

Because infected individuals shed oocysts for approximately one week after symptoms resolve, there is an increased risk of future outbreaks.

Lack of awareness and failure to reduce transmission of these protozoan parasites using alternative water-sanitizing technologies make future Cryptosporidium and Giardia outbreaks inevitable.

While substantial regulatory efforts have been directed at drinking water, there has not been a corresponding effort to regulate public recreational water facilities.

Alternative water-sanitizing techniques that have proven successful for the disinfection of protozoa include the use of ozone and ultra-violet (UV) light as disinfectants.

Alternatively, Naegleria is highly susceptible to chlorination and as such is recommended as an adequate disinfection technique.

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