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Table 1 Examples of incidents and case studies of acute gastrointestinal illnesses, chronic gastrointestinal illnesses connected to the consumption of cyanobacteria-contaminated water, and chronic gastrointestinal illnesses connected to the recreational activities in cyanobacteria-contaminated water

From: Effects of cyanobacterial toxins on the human gastrointestinal tract and the mucosal innate immune system

Locality Years Cyanobacteria Cyanotoxins Description Refs.
Acute gastrointestinal illnesses connected to the consumption of cyanobacteria-contaminated water
USA, West Virginia, Charlestone 1930 Microcystis bloom n.a. Massive water blooms of Microcystis sp. in the Ohio and Potomac Rivers linked to gastrointestinal illness (abdominal pain, nausea, vomiting, and diarrhea) in ≈ 5000–8000 people out of 60,000 inhabitants, despite water treatment by precipitation, filtration and chlorination [26]
Zimbabwe, Harare 1960–1965 Microcystis bloom n.a. Annual increases of children hospitalizations due to gastroenteritis in a city area supplied with drinking water from a water reservoir during a cyanobacterial bloom decay, no infectious agents detected, and populations of children from other areas supplied with water without bloom development were unaffected [27]
USA, Pennsylvania, Sewickley 1975 Schizothrix calcicola n.a. Gastrointestinal outbreak in ≈62% of 8000 inhabitants supplied with drinking water from a contaminated water source [28, 29]
Australia, Palm Island 1979 Cylindrospermopsis raciborskii CYN implicated After the use of copper sulfate to control a dense cyanobacterial bloom in water supply, 139 children and 10 adults suffered with severe hepatoenteritis and gastroenteritis (malaise, nausea, vomiting, headaches, hepatomegaly, diarrhea, and dehydration), requiring hospitalization with an evidence for liver and renal damage [16, 30]
Brazil, Itaparica Dam 1988 Microcystis sp., Anabaena sp. n.a. 2000 gastroenteritis, with 88 cases resulting in death, reported over 42-day period after flooding a newly constructed dam. Cases were restricted to the areas supplied with drinking water from the dam; cyanobacteria were detected in untreated water. No other toxicants or infectious agents were identified. [31]
Sweden, Malmo area 1994 Planktothrix agardhii, Microcystis sp. MCs Accidental mixing of untreated river water with treated drinking water during a cyanobacterial bloom; 121 people from 304 experienced nausea, abdominal pain, vomiting, and diarrhea accompanied with muscle pain, headaches and fever. No pathogens detected upon clinical examinations of patients or in the river water [32]
Australia, South Australia. Murray River 1995 Most common: Dolichospermum circinale, Microcystis aeruginosa, Aphanizomenon sp., Planktothrix sp. n.a. Increased incidence of gastrointestinal symptoms in people consuming treated (chlorinated) river water during a period of raised cyanobacterial cell counts in the river; gastrointestinal and dermatological symptoms in people using untreated river water for domestic purposes when compared to people using rain water [33]
Namibia, Windhoek 2000 Microcystis sp., Oscillatoria sp., Anabaena sp., Merismopedia sp. MCs Liver damage (increased serum levels of liver enzymes) and diarrhea during the occurrence of cyanotoxins and cyanobacteria in treated drinking water, there was a positive correlation between diarrhea and chlorophyll a concentration in the water [34]
Serbia, Uzice 2013 Planktothrix rubescens MCs Cyanobacteria and cyanotoxins found in final treated water in December 2013; significantly higher incidence of gastrointestinal, skin, and subcutaneous diseases detected during bloom periods in 2012–2015 [35]
USA, Ohio, Lucas County 2014 n.a. MCs Microcystin levels in drinking water reached 3.19 µg/L, a do-not-drink water advisory for 3 days was issued. In 16.2% out of > 100,000 households, at least one person reported physical health symptoms attributed to the advisory; gastrointestinal symptoms were most commonly reported (diarrhea 12.1%, nausea 9.1%, and vomiting 6.2%). Eye and skin irritation, headaches, and respiratory symptoms were also reported [36]
Chronic gastrointestinal illnesses connected to the consumption of cyanobacteria-contaminated water
China, Zhejiang, Haining 1977–1996 n.a. MCs Greater incidence of colorectal cancers in patients relying on river and pond water as drinking water source in comparison to people using underground well water or tap water. Microcystins detected in river and pond water, their concentrations were correlated with the cancer incidence [21]
China, Jiangsu, Wuxi n.a. n.a. MCs Microcystin in drinking water was positively correlated with male overall cancer mortality and male stomach cancer mortality, but negatively correlated with male intestinal cancer mortality [24] a
USA, Florida 1981–1998 n.a. n.a. No significant associations between the incidence of colorectal cancer in people living within the area supplied with surface water compared to people supplied with deep ground water in GIS-based study [25]a
Serbia 1999–2008 Microcystis sp., Aphanizomenon sp., Anabaena sp., Planktothrix sp. MCs Geographical incidence of 13 cancers (brain; bronchus and lung; heart, mediastinum, and pleura; ovary; testis; kidney; stomach; small intestine; colorectum; retroperitoneum and peritoneum; leukemia; malignant melanoma of skin and primary liver cancer) positively correlated with the occurrence of cyanobacterial blooms and toxins [23]
Portugal 2000–2010 Microcystis aeruginosa, Aphanizomenon sp., Oscillatoria sp. n.a. Populations exposed to cyanobacteria-contaminated drinking water had higher serum levels of liver enzymes, and higher incidence of cancers (liver, colon, and rectum cancer) [22]a
USA, Ohio, Celina, Grand Lake St. Marys 1996–2008 Aphanizomenon sp., Microcystis sp., Anabaena sp., Planktothrix sp. MC, CYN, ATX, STX Periodically supplied with cyanobacteria-contaminated surface water; comparison of cancer incidence in the population (hepatocellular and colorectal cancer) was inconclusive compared to two groundwater supplied cities [37]a
Gastrointestinal illnesses connected to the recreational activities in cyanobacteria-contaminated water
Canada, Saskatchewan 1959 Microcystis sp., Dolichospermum circinale n.a. Despite animal deaths and warnings against recreational use, people swam in cyanobacteria-contaminated lake; 13 people suffered from headaches, weakness, nausea, stomach cramps, vomiting, painful diarrhea, muscle, and joint pains. No pathogens detected, cyanobacteria were detected in the vomit and stool of one patient [38]
USA, Pennsylvania 1979 Anabaena sp. n.a. Hay fever-like and gastrointestinal symptoms following recreational water activities in cyanobacteria-contaminated lake, no pathogenic agents were detected [39]
Great Britain, Staffordshire 1989 Microcystis sp. n.a. 10 out of 20 army recruits suffered from gastrointestinal symptoms (vomiting, diarrhea, and abdominal pain) and other health issues (lips blistering and sore throat) after swimming and canoe training in water with cyanobacterial bloom. Two recruits developed atypical pneumonia [9]
Australia, New South Wales, Victoria 1995 Microcystis sp., M. aeruginosa, Anabaena sp., Aphanizomenon sp., Nodularia spumigena n.a. Epidemiological study (777 exposed, 75 control) reported positive correlation between exposure to cyanobacteria during recreation and diarrhea, vomiting, flu-like symptoms, skin rashes, mouth ulcers, and eye and ear irritations observed 2–7 days after the exposure. Severity of the symptoms depended on bloom density and duration of the recreational activity. Hepatotoxicity was assessed by a bioassay [40]
Australia, New South Wales, Florida 1999–2002 Microcystis sp., Anabaena sp., Planktothrix sp., C. raciborskii, A. ovalisporum MCs, CYN, ATX (low levels) Respiratory symptoms, gastrointestinal illness, eye and ear irritation associated with recreational use of cyanobacteria and cyanotoxin-contaminated water [41]
Great Britain, Littleborough 1996 Planktothrix agardhii MCs Cyanobacterial bloom caused vomiting, fever, facial rashes, asthma, and dry sporadic cough in 11 cadets practicing canoe-capsizing [42]
Finland, lakes Sompanen, Salajarvi, Iso-Kukkanen 2002–2003 Dolichospermum lemmermannii STXs Recreational activities in lakes with cyanobacterial bloom caused skin rashes, eye irritations, fever, and abdominal pains in 2–10-year-old children [43]
Argentina, Salto Grande Dam 2007 Microcystis sp. MCs 19-year-old man practicing jet ski exposed for more than 2 h to a dense cyanobacterial bloom developed gastrointestinal malaise, nausea, vomiting, and muscle weakness a few hours later. His condition worsened during the next 4 days, developed into pulmonary problems and dyspnea, followed by hepatotoxicosis [10]
Canada 2009 n.a. MCs, LPS Increased incidence of gastrointestinal symptoms (diarrhea, vomiting, eventually nausea, fever, and abdominal cramps) in residents with full recreational contact at cyanobacteria-contaminated lake (swimming, waterskiing, windsurfing, etc.). These symptoms were also reported in cases of limited contact with contaminated water (fishing using watercraft). Significantly higher incidence of various other symptoms (muscle pain, skin symptoms, and ear symptoms) in populations supplied with treated surface water from cyanobacteria-contaminated supplies. The symptoms were correlated with concentrations of lipopolysaccharides [14, 15]
Finland, brackish, and freshwater localities 2010 n.a. MCs, NOD, ATX, STX, LPS Health issues reported upon recreational activities in cyanobacteria-contaminated water: fever (58%), gastrointestinal symptoms (53%), nausea (34%), skin irritation (34%), headaches (32%), eye–ear–nose–throat irritation (29%), and others (16%). While concentrations of cyanotoxins and LPS were relatively low, Aeromonas sp. virulence genes were frequently detected in the bacteria isolated from the water samples [44]
USA, Ohio, New York, Washington 2009–2010 n.a. MCs, STX, CYN, ATX 11 outbreaks of cyanobacterial blooms resulted in at least 61 illnesses (two hospitalizations, no known death), effects included dermatologic signs or symptoms (8); gastrointestinal signs or symptoms (8); respiratory signs or symptoms (6); fever (5); headache (4); neurologic signs or symptoms (4); ear symptoms (5); and eye irritation (3). In each of the outbreaks for which oral exposure was reported, affected persons had gastrointestinal signs or symptoms [45]
USA, Kansas, Milford Lake 2011 Microcystis sp. MCs 7 reports of human illnesses confirmed as associated with cyanobacterial blooms, primary symptoms included: eye and upper respiratory tract irritation (71%), rash (29%), and gastrointestinal (14%). The primary route of exposure included direct contact [46]
Uruguay, Montevideo, Carrasco and Malvín beaches 2015 Microcystis sp. MCs A family with a 20-month-old child suffered gastrointestinal symptoms after recreational activities; the symptoms were self-limited except in the child, who was hospitalized with diarrhea, vomiting, fatigue, and jaundice. Serum levels of liver enzymes and bilirubin indicated liver damage resulting in acute liver failure 5 days later (liver transplant 20 days later). Microcystins were detected in the liver tissue [11]
  1. Ref.: reference(s), n.a.: not assessed, ATX: anatoxin, CYN: cylindrospermopsin, GIS: geographical information system, LPS: lipopolysaccharide, MCs: microcystins, NOD: nodularin, STX: saxitoxin. Note: The planktonic species of the genus Anabaena are currently taxonomically reclassified as genus Dolichospermum
  2. aRetrieved from [12]