Cryptosporidium (Crypto)
This parasite can cause diarrhea in animals and humans. Cryptosporidiosis is usually mild for most people but can cause severe, potentially fatal gastrointestinal illness in those with compromised immune systems. This organism is the No. 1 culprit for diarrheal illness in swimming pools because of its resistance to chlorine.
E. coli
Most types of this bacterium, which lives in human intestines, are harmless, but there are harmful E. coli that cause illness. These toxigenic strains of E. coli can cause diarrhea, including bloody diarrhea that can, in extreme cases, cause kidney failure and even death, especially in young children.
Fecal coliform bacteria
Fecal coliform are microorganisms normally present in soil and sewage that can get into a pool or spa in a variety of ways, including on the body of a patron. The microorganisms can cause disease if contaminated water is accidentally swallowed or by entering the body through the nose, ears or cuts on the skin.
Giardia
Giardiasis is an infection of the small intestine caused by a microscopic organism called giardia lamblia. The disease can cause abdominal pain, diarrhea, gas or bloating, headache, loss of appetite or vomiting. Symptoms usually improve in a few weeks, but they can last longer or recur.
Norovirus
Norovirus is the most common cause of gastroenteritis in the United States, according to the Centers for Disease Control and Prevention. The bacteria can cause diarrhea, vomiting and stomach pain. The CDC estimates that about 1 in every 15 Americans will get norovirus illness each year.
Pseudomonas aeruginosa
Pseudomonas aeruginosa is a common bacterium that may be present on human skin, hair and in feces. This microscopic germ can cause dermatitis, also called “hot tub rash,” which can include an itchy rash — often worse on the parts of the body covered by a swimsuit — or pus-filled blisters around hair follicles.
Shigella
Shigellosis is an infectious disease caused by a group of bacteria called shigella. Most people infected with shigella develop diarrhea, fever and stomach cramps a day or two after exposure. A severe infection with high fever may be associated with seizures and kidney failure in children younger than 2.
Related story
Gazette investigation: Corridor pools repeatedly closed for health, safety violations