Human fatalities from cyanobacteria: chemical and biological evidence for cyanotoxins.

Abstract

An outbreak of acute liver failure occurred at a dialysis center in Caruaru, Brazil (8 degrees 17' S, 35 degrees 58' W), 134 km from Recife, the state capital of Pernambuco. At the clinic, 116 (89%) of 131 patients experienced visual disturbances, nausea, and vomiting after routine hemodialysis treatment on 13-20 February 1996. Subsequently, 100 patients developed acute liver failure, and of these 76 died. As of December 1996, 52 of the deaths could be attributed to a common syndrome now called Caruaru syndrome. Examination of phytoplankton from the dialysis clinic's water source, analyses of the clinic's water treatment system, plus serum and liver tissue of clinic patients led to the identification of two groups of cyanobacterial toxins, the hepatotoxic cyclic peptide microcystins and the hepatotoxic alkaloid cylindrospermopsin. Comparison of victims' symptoms and pathology using animal studies of these two cyanotoxins leads us to conclude that the major contributing factor to death of the dialyses patients was intravenous exposure to microcystins, specifically microcystin-YR, -LR, and -AR. From liver concentrations and exposure volumes, it was estimated that 19.5 microg/L microcystin was in the water used for dialysis treatments. This is 19.5 times the level set as a guideline for safe drinking water supplies by the World Health Organization.

A review of neurotoxicity of microcystins

“…Due to the hepatotoxicity of MCs, the liver was considered to be the main target of MCs in previous study; however, in the tragedy which happened in Caruaru, Brazil, on February 1996, 131 patients were intravenously exposed to various concentrations of MCs and 116 of them (89 %) presented general neurological symptoms including dizziness, tinnitus, vertigo, headache, vomiting, nausea, mild deafness, visual disturbances, and blindness (Azevedo et al 2002;Pouria et al 1998;Carmichael et al 2001). It is confirmed that the transport of MCs crossing blood-brain barrier can be mediated by organic anion-transporting peptide (rodent Oatps; human OATPs), implying that the brain may also be one of the main targets of MCs (Fischer et al 2005).…”

Responses and toxin bioaccumulation in duckweed (Lemna minor) under microcystin-LR, linear alkybenzene sulfonate and their joint stress

“…Some cyanobacterial species are known to produce different types of toxins including microcystins (MCs). MCs are toxic to terrestrial and aquatic organisms [1][2][3][4], as well as humans [5]. MCs can bioaccumulate in the tissues of animals [6,7] and plants [8,9], and thus could be a threat to human health through the food chain.…”

Cyanobacterial blooms in freshwaters bodies in a semiarid region, northeastern Brazil: A review

“…Studies focusing on the dominance and toxicity of these organisms emerged only after the "Caruaru tragedy" in 1996, when dozens of renal patients in a haemodialysis clinic died after intravenous exposure to microcystins (Carmichael et al, 2001;Azevedo et al, 2002). After this incident, research efforts were directed to monitor various supply reservoirs, including the important report by Bouvy et al (2000), which monitored water quality and the occurrence of bloom-forming cyanobacteria Cylindrospermopsis Seenayya & Subba Raju in 39 reservoirs in Pernambuco state.…”