Do Natural Water Blooms Cause Irritation/Allergy?

Abstract

P-117 Introduction: Cyanobacterial blooms and scums occur in the same period of recreation, bathing in freshwaters. That is why it is needed to examine experimentally the allergenic and irritative effects of cyanobacteria. There are some data on contact irritative and allergenic effects of cyanobacteria. In a retrospective epidemiological study in Hungary it was found that in 1994 a lot of children (almost one hundred) suffered from skin and eye irritation in a heavy bloom of Microcystis aeruginosa. Methods: Microcystis aeruginosa, Anabaena flos-aquae, Aphanizomenon flos-aquae and Cylindrospermopsis raciborskii are the most common species in Hungarian freshwaters. Sensitization test on albino guinea pigs, intradermal reactivity and occular irritation test on albino rabbits with freeze dried algal suspension in physiological salt solution were carried out modelling the human reactivity. All the axenic strains were examined for endotoxin (lipopolysaccharide) content by LAL (Lymulus Amobocyte Lysate) test. Results: Natural bloom and strain samples were examined in sensitization and irritation tests and no correlation was found between the toxin content and allergenic character. The most toxic one was not the most allergenic sample, but the non-toxic Aphanizomenon[r] was the most allergenic one. The axenic strains were not allergenic at all. All axenic samples containing 50–170 IU/ml lipopolysaccharide (LPS) endotoxins can cause inflammatory symptoms if they reach the blood system. There was no correlation between the toxin content and the LPS content as well. Case study: Clear freshwater pond using for bathing was closed for two weeks in the high season because more than 40 patients suffered from skin blistering and rashes and it was thought that the high amount of filamentous cyanobacteria (chlorophyll a was 118.4 mg/m3) might cause the symptoms. It turned out that some patients did not bathe in the water at all, so the real causes were to be looked for. In the same time a severe gradation of the caterpillars of the moth Thaumetopoea processionea occurred in the forest of oaks surrounding the pond. These caterpillars have integumental glands that produce an urticating chemical. They can release their poisonous setae (hairs) or spines into the environment where they can be contacted on skins. They caused dermatitis as known erucism. Discussion and Conclusions: Although there is experimental evidence for the fact that the cyanobacteria can cause allergenic and irritative symptoms diagnosis should be established carefully as it turned out from the case study.