Toxigenic cyanobacteria blooms favored by environmental conditions and eutrophication of water bodies worldwide occur periodically [1
]. Cyanobacteria genera, such as Microcystis
, and Nostoc
, among others, are capable of producing a wide range of toxins, like microcystins, cylindrospermopsins, nodularin, and anatoxins [3
]. The presence of cyanobacteria blooms in water bodies affects water quality owing to the production of cyanotoxins and odoriferous compounds. In the La Plata basin one of the most toxic and frequently-present cyanobacteria is Microcystis
sp., often producing microcystin-LR (MC-LR) and [D-Leu1
]. These toxins are considered among the most toxic hepatotoxins produced by cyanobacteria.
Furthermore, the water bodies where blooms occur are commonly used for recreational purposes or as drinking water sources. People and animals can, therefore, be exposed to cyanobacteria and their toxins via several pathways. This worrying situation constitutes a major health and environmental hazard [3
MCs have been associated with damage to human and animal health, causing different characteristic patterns of damage that depend on the route, intensity, and time of exposure. Reported diseases caused by cyanobacterial blooms and/or MCs vary in severity, ranging from death due to liver failure (Caruaru syndrome) [7
] and gastrointestinal syndromes [9
] to skin damage, respiratory problems [14
], and liver cancer [16
Recreational exposure to cyanobacterial blooms mainly involves oral, dermal, and inhalation pathways, depending on the type of activities undertaken in the water body.
This type of exposure has been suspected in humans but not always confirmed, given the lack of detection of cyanotoxins in biological samples of exposed people and because cyanobacterial hepatotoxicosis is often underdiagnosed [19
In this work we present a case of a family of three adults and a 20-month-old child who engaged in recreational activities, including bathing at the Carrasco and Malvín beaches in Montevideo, Uruguay, during the summer algal bloom in January 2015.
A few hours after the last exposure episode, the family members developed gastrointestinal symptoms (diarrhea) which were rapidly self-limited in the three adults. The girl, however, continued to present gastrointestinal symptoms, such as diarrhea and vomiting, developing fatigue and jaundice, until finally, five days after exposure, she was admitted to the intensive care unit of a toxicology medical center (CIAT Uruguay). Laboratory tests showed increased serum levels of alanine aminotransferase (ALT: 1814 UI·L−1), aspartate aminotransferase (AST: 1946 UI·L−1), total bilirubin (8.15 mg·dL−1), direct bilirubin (4.8 mg·dL−1), and International Normalized Ratio (INR > 3). The patient was subsequently referred to the liver transplant center of the Italian Hospital in Buenos Aires, Argentina. Based on the epidemiological history of the patient, who had been bathing in the water with her family at the Carrasco and Malvín beaches (Montevideo, Uruguay) during a period of harmful algal bloom (HAB), the final diagnosis was acute liver failure related to cyanobacteria toxicity.
Our research group has performed histological studies and MCs determination in the explanted liver. We have also summarized the report on the environmental monitoring of Montevideo beach water quality undertaken by the authorities of Montevideo city between December 2014 and January 2015 [21
The results indicate that the recreational exposure to MCs played a preponderant role in the development of acute hepatic failure suffered by the patient.
People frequently engage in recreational activities involving contact with the environment without being aware of possible adverse health effects arising from a range of contaminants present in the surroundings.
Harmful algal bloom (HAB), characterized by the exponential growth of several species of toxin-producing Cyanobacteria, frequently occurs in summer and constitutes a sanitary and environmental problem all around the world [2
Microcystins (MCs), one of the most widely distributed groups of cyanotoxins, are part of a potent hepatotoxin group produced by genera such as Microcystis
, and Nostoc
, among others. Two of these toxins, Microsytin-LR (MC-LR) and [DLeu1
]MC-LR, are usually present in the Río de La Plata estuary during the period of algal blooms [4
HAB have been associated with periodic incidents of human and animal illness and death all around the world. Depending on the kind of contact that people have with cyanobacteria and their toxins, a condition characterized by different symptoms is defined. The first records of gastrointestinal diseases due to contact of the population in several cities on the Ohio River shore with cyanotoxins date from 1931 [9
]. Similar alterations were observed in Harare, Zimbabwe, where children from certain areas of the city developed gastroenteritis every year coinciding with the senescence of Microcystis
One of the worst gastrointestinal toxic events, even with some lethal cases, relating to cyanotoxins, occurred in 1988 in Paulo Alfonso, Bahia, Brazil. After the construction of the Itaparica dam there was a severe epidemic of gastroenteritis associated with an Anabaena
sp. bloom, in which about 2000 cases were reported within a period of 42 days, 88 of which were fatal; those mainly affected were children [12
Furthermore, there are numerous reports of people who suffered symptoms, such as conjunctivitis, earache, hay fever-like syndrome, swollen lips, allergic dermatitis, rush, itching, and headache, after consuming water or coming into contact with water during a cyanobacterial bloom [23
One of the most severe and well-documented cases of acute exposure to cyanotoxins occurred in Caruaru, Brazil, where 55 dialysis patients developed hepatic failure and died due to the use of cyanotoxin-contaminated water in the dialysis procedure. In this case, microcystins were identified in samples from the dialysis center filter, specifically in patient’s blood and post-mortem liver samples [7
Another important way in which population come into contact with cyanobacterial blooms is through recreational activities. However, the effects on health of recreational MCs exposure are not yet sufficiently understood and this type of poisoning often remains undiagnosed. In previous work we reported an acute intoxication case due to recreational exposure to cyanobacteria occurring in Salto Grande Dam, Entre Ríos, Argentina in January 2007. Whilst engaging in nautical sports in this lake, a young man was immersed in an intense bloom of Microcystis
sp. A level of 48.6 μg·L−1
of microcystin-LR was detected in water samples. Four hours after exposure, the patient showed nausea, abdominal pain, and fever. The initial diagnosis was stress. Three days later, dyspnea and respiratory distress were reported. The patient was hospitalized in intensive care and was diagnosed with atypical pneumonia. Finally, a week after the exposure, the patient developed hepatotoxicosis with a significant increase of hepatic damage biomarkers (ALT, AST and γGT). Complete recovery took place within 20 days [14
In this work we report the symptoms suffered by a family after recreational activities at beaches in Montevideo, Uruguay in January 2015. Environmental monitoring of Montevideo beach water quality undertaken by the authorities of Montevideo city indicated, for January 2015, fecal coliform values below the limit of 1000 cfu·dL−1
and the presence of highly-toxic blooms (mainly Microcystis
) with foam formation and average MC levels of 2.9 mg·L−1
and a maximum level of 8.2 mg·L−1
A few hours after the last exposure event, three adults developed gastrointestinal symptoms which were rapidly self-limited and a 20-month-old girl suffered gastrointestinal symptoms followed by acute liver failure, ending in liver transplant.
Elevated levels of ALT, AST, total and direct bilirubin detected in the patient’s plasma were consistent with the observed liver damage. Likewise, these results are not surprising since the liver is the main target of microcystins and these toxins are actively transported within the hepatocytes. Thus, the inhibition of protein phosphatases, the main mechanism of action of these toxins, rapidly damages these metabolically highly-active cells.
The coagulopathy developed by the patient, characterized by alteration in PT and INR levels, is physiologically associated with the observed hepatic injury and the consequent alteration in protein synthesis factors necessary for normal functioning of the clotting and fibinolytic systems. Similar alterations in these parameters were also reported in studies which describe the biochemical outcome of Caruaru’s patients [7
] and others performed on the plasma of hemodialysis patients sub-lethally exposed to microcystins [24
The clinical parameters led to an initial diagnosis of acute liver failure, and serological evaluation had pointed to autoimmune hepatitis type II as the cause of liver failure. However, the patient did not improve after pharmacological treatment and was derived to undergo liver transplant. Liver histological studies had indicated a pattern of damage characterized by liver hemorrhagic necrosis, portal tracts without inflammatory activity and parenchyma with nodular regeneration, which is not typical for autoimmune hepatitis [25
Although autoimmune hepatitis type II could have been triggered by several factors, including exposure to hepatotoxic substances, such as MCs, the damage observed at the histological level and the presence of MC-LR and [DLeu1]MC-LR in the liver, led us to consider a preponderant role for cyanotoxins in the development of the acute liver failure suffered by the patient.
The presence of MC-LR in the liver sample was confirmed by the retention time in comparison with MC-LR standard and the molecular ion ([M + H]+ m
]. Due to the lack of [D-Leu1
]MC-LR standard, the identification of this toxin was performed using the molecular ion ([M + H]+ m
1037.6045), the doubly-charged molecular ion [M + H]+ m
519.3057, and the main fragment ions previously reported [Arg-MeAsp-(155)-Ala-Mdha + H]+ m
595.3750 ion and [(M-PhCH2CH(OMe)) + H]+ m
903.5334 ion [26
The toxins found in the damaged liver constitute a toxicological nexus that confirms the child’s exposure to HAB during recreational activities. We surmise that the exposure characteristics were intermittent, sub-acute for several days, and absorbed mainly via oral and dermal routes. Taking into account the MCs levels found in the child’s liver and toxin levels on Montevideo beaches (mean value of 5 mg MCs·L−1
) reported by the authorities [21
], we estimate that the girl had been exposed to the toxin contained in at least 1.78 L of the water.
Several studies were performed on mice exposed to different doses of purified MC-LR (25 µg·kg−1
; 35 µg·kg−1
) via i.p. Levels of toxin were detected in liver ranging from 81.1 ng·g−1
to 460 ng·gr−1
]. Even though in the current case we cannot know the exact dose and number of exposure events suffered, the values found in the liver of the patient (2.4 ng MC-LR·g−1
and 75.4 ng [D-Leu1
liver) could explain the damage observed in the liver.
Previously, micrcosystin levels in human liver were only determined in Caruaru victims. Carmichael et al. [8
] reported that the average level of microcystins found in 52 liver samples from 39 fatal victims was 223 ng·g−1
, ranging between 50.2 and 272 ng·g−1
estimated by ELISA assay. Consistent with this, in the present case 77.8 ng total MCs·g−1
of liver were found using the LC-Orbitrap-MS system.
Our findings show that exposure to toxic cyanobacteria blooms generated differential effects in adults (gastrointestinal symptoms) and a baby (acute liver failure). This difference between the pathologies presented in adults and the child may be due to: (i) the relative dose determined mainly by the duration of contact with the bloom and body size; (ii) higher body surface/body weight ratio in children than in adults, which acquires particular relevance for the dermal route; (iii) level of maturation of the liver and intestinal system and the quality of intestinal flora; and (iv) higher biological susceptibility to the development of diseases with autoimmune components.
In this work we have reported a case of recreational exposure to cyanobacteria and cyanotoxins, suffered by a family (three adults and a 20-month-old child) during January 2015 on the beaches of Uruguay. The adults had only self-limiting gastrointestinal symptoms while the child had more severe gastrointestinal condition resulting in acute liver failure requiring liver transplant. To the best of our knowledge this is the first report on the presence of MC-LR and [D-Leu1] MC-LR in liver of a patient who has undergone recreational exposure to a harmful algal bloom dominated by Microcystis.
This report highlights the need to encourage and promote discussion on the health assessment which focus on environmental health determinants such as toxigenic cyanobacteria bloom and their toxins. Likewise management frameworks should be generated through cooperation and co-financing in order to ensure adequate data sharing among all the sectors involved, at the same time intensifying research with a view to providing improved human health protection.
It is, therefore, necessary to include this type of hepatotoxicosis in diagnosis protocols, especially in areas affected by harmful algae blooms, so that medical staff will be aware of the pathology and be able to make a correct differential diagnosis.
Furthermore, institutional links should be established, allowing samples to be derived from hospitals and health centers to laboratories and other entities specializing in cyanotoxins in order to detect the presence of MCs in biological fluids as a confirmatory parameter.