and Recreational Waters in Minnesota
Microscopic organisms occur normally in water but most do not harm us and in fact, many are beneficial. However, microorganisms that cause disease may be found in surface waters from a number of sources. Waterborne pathogens are disease-causing germs that live in water, and can be classified as bacteria, viruses, protozoa, or algae. They can enter streams and lakes with sewage, wastes, or runoff. If you detect a spill or leak that is contaminating a water source, immediately notify the Minnesota Duty Officer.
Some examples of microorganisms that will survive and/or reproduce in surface waters and infect swimmers include:
- Escherichia coli (E. Coli O157)
- Norovirus Infection (aka Norwalk virus, calicivirus, viral gastroenteritis)
- Shigellosis (Shigella)
- Cryptosporidiosis (Cryptosporidium spp.)
- Giardiasis (Giardia)
It is important to note that individuals most at risk for disease transmission in recreational water are small children (particularly those prone to putting their hands in their mouth or to swallowing water) and individuals with compromised immune systems. The individuals most likely to release bodily wastes that may contain pathogens (e.g. diarrhea) are also small children.
In 2001, hundreds of cases laboratory-confirmed infectious diseases were reported to the Minnesota Department of Health, including:
- 1,061 persons with Giardia,
- 953 with Campylobacter,
- 493 with Shigella,
- 693 with Salmonella,
- 219 with E. coli O157,
- 198 with Cryptosporidium, and
- 47 with viral hepatitis A.
In reality, laboratory-confirmed infections with the above pathogens represent only the “tip of the iceberg”. The actual number of cases was likely 10 to 40 times greater than reported laboratory confirmed infections (depending on the pathogen). Many infections are self-limited, but hospitalization rates for most of these pathogens are between 10% and 30%.
Children and the elderly comprise the most heavily-affected age groups. During 2001, eight swimming related outbreaks were identified, including four due to Cryptosporidium, one due to Shigella, one due to both Cryptosporidium and Shigella, one due to E. coli 0157 and one due to Norovirus. The venues for these outbreaks included swimming beaches, a camp swimming pool, a hotel swimming pool, and a community swimming pool. One outbreak of cryptosporidiosis in 2000 at a swimming beach resulted in at least 220 cases; diaper- aged children were thought to be the source of contamination.
It isn’t practical to sample and analyze water for all the pathogens that might affect human health, and so fecal coliform and E. coli (Escherichia coli) are used as two different measures of the presence of bacteria from fecal sources.
Fecal coliform bacteria are a group of bacteria that occur in large numbers in the gut and feces of humans and other warm-blooded animals. They enter streams and lakes with sewage, wastes, or runoff. Most fecal coliforms are normal inhabitants of the digestive tract and considered relatively harmless. However, their detection in water may indicate the presence of feces, that may contain more harmful microorganisms found. E. coli is the major species of the fecal coliform group.
E. coli is the abbreviated name of the bacterium in the family Enterobacteriaceae named Escherichia coli. The name "E. coli" encompasses a wide range of bacteria, some of which help us and some of which hurt us. Approximately 0.1% of the total bacteria within an adult’s intestines is represented by E. coli. The presence of E. coli and other bacteria within our intestines is necessary for us to develop and operate properly. A notorious exception is E. coli strain 0157:H7, an emerging pathogen that produces a powerful toxin and can cause severe illness. Symptoms of poisoning by E. coli 0157:H7 include bloody diarrhea, kidney damage, and occasionally death. The majority of E. coli associated illnesses are acquired by eating contaminated food, but contaminated drinking water or water swallowed while swimming is another source.
The potentially severe consequences of E. coli O157 in child care settings was illustrated in 2001 with two deaths of preschool aged children in Minnesota due to hemolytic uremic syndrome caused by E. coli O157 infections; each of these cases were part of E. coli O157 outbreaks associated with child care settings.
Shigella bacteria are fecal bacteria that can cause diarrhea. People can come into contact with Shigella bacteria in recreational waters that have been contaminated with sewage or feces (e.g. from soiled diapers) by drinking the water or during swimming activities.
A number of viruses may also cause diarrhea and other gastrointestinal upsets. These include Norwalk viruses and rotoviruses. These may be present in recreational water contaminated with feces.
Noroviruses are a group of viruses that cause the “stomach flu,” or
gastroenteritis in people. The term norovirus was recently approved as
the official name for this group of viruses. Several other names have
been used for noroviruses, including:
norwalk-like viruses, caliciviruses, and small round structured viruses.
Viruses are very different from bacteria and parasites, some of which can cause illnesses similar to norovirus infection. Viruses are much smaller, are not affected by treatment with antibiotics, and cannot survive very long outside of a person’s body.
Giardiasis (“Giardia”) is a diarrheal illness caused by Giardia intestinalis (also known as Giardia lamblia), a one-celled, microscopic protozoan parasite that lives in the intestine of people and animals. During the past 2 decades, Giardia has become recognized as one of the most common causes of waterborne disease (drinking and recreational) in humans in the United States.
Cryptosporidiosis (“Crypto”) is a gastrointestinal illness caused by a microscopic parasite known as Cryptosporidium parvum. Drinking untreated water and accidentally ingesting water while swimming are common sources. Symptoms of Crypto include diarrhea, loose or watery stool, stomach cramps, upset stomach, and a slight fever. Some people have no symptoms.
Runoff into lakes often contains excess nutrients such as nitrates and phosphates. Blue-green Algae feed on these nutrients and grow at high rates known as “blooms.” Although algae themselves are not generally harmful, as they grow they release by-products that may cause gastrointestinal illness.
For more information about blue green algae, visit the pages below.
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