SummaryInnate immune system deficiency may predispose to severe infections such as Legionnaires' disease. We have investigated the role of mannose-binding lectin (MBL) deficiency in the Melbourne Aquarium Legionnaires' disease outbreak. Serum samples from patients and controls that were exposed but shown to be uninfected from the Melbourne Aquarium Legionnaires' disease outbreak were tested for MBL function (C4 deposition) and level (mannanbinding). MBL function was lower in Legionnaires' disease cases than in ageand sex-matched uninfected, exposed controls. The frequency of MBL deficiency with C4 deposition < 0·2 U/ml was significantly higher in Legionnaires' disease cases than in controls. This also applied to Legionnaires' disease cases requiring hospital care. There was no difference in MBL mannan-binding levels between Legionnaires' disease patients and controls. There was no significant interval change in MBL function or level after a mean of 46 days. MBL complement activation functional deficiency appears to predispose to Legionnaires' disease.

Rivers discharging to the Great Barrier Reef carry complex pesticide mixtures. Here we present a first comprehensive ecotoxicological risk assessment using species sensitivity distributions (SSDs), explore how risk changes with time and land use, and identify the drivers of mixture risks. The analyzed data set comprises 50 different pesticides and pesticide metabolites that were analyzed in 3741 samples from 18 river and creek catchments between 2011 and 2016. Pesticide mixtures were present in 82% of the samples, with a maximum of 23 pesticides and a median of five compounds per sample. Chemical-analytical techniques were insufficiently sensitive for at least seven pesticides (metsulfuronmethyl, terbutryn, imidacloprid, clothianidin, ametryn, prometryn, and thiamethoxam). The classical mixture concepts of concentration addition and independent action were applied to the pesticide SSDs, focusing on environmental threshold values protective for 95% of the species. Both concepts produced almost identical risk estimates. Mixture risk was therefore finally assessed using concentration addition, as the sum of the individual risk quotients. The sum of risk quotients ranges between 0.05 and 122 with a median of 0.66. An ecotoxicological risk (i.e., a sum of individual risk quotients exceeding 1) was indicated in 38.5% of the samples. Sixteen compounds accounted for 99% of the risk, with diuron, imidacloprid, atrazine, metolachlor, and hexazinone being the most important risk drivers. Analysis of land-use patterns in catchment areas showed an association between sugar cane farming and elevated risk levels, driven by the presence of diuron.

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