Correction: The Effect of Increasing Water Temperatures on Schistosoma mansoni Transmission and Biomphalaria pfeifferi Population Dynamics: An Agent-Based Modelling Study

Introduction: There is increasing interest in the control and elimination of schistosomiasis. Little is known, however, about the likely effects of increasing water-body temperatures on transmission. Methods: We have developed an agent-based model of the temperature-sensitive stages of the Schistosoma and intermediate host snail life-cycles, parameterised using data from S. mansoni and Biomphalaria pfeifferi laboratory and fieldbased observations. Infection risk is calculated as the number of cercariae in the model, adjusted for their probability of causing infection. Results: The number of snails in the model is approximately constant between 15–31uC. Outside this range, snail numbers drop sharply, and the snail population cannot survive outside the range 14–32uC. Mean snail generation time decreases with increasing temperature from 176 days at 14uC to 46 days at 26uC. Human infection risk is highest between 16–18uC and 1 pm and 6–10 pm in calm water, and 20–25uC and 12–4 pm in flowing water. Infection risk increases sharply when temperatures increase above the minimum necessary for sustained transmission. Conclusions: The model suggests that, in areas where S. mansoni is already endemic, warming of the water at transmission sites will have differential effects on both snails and parasites depending on abiotic properties of the water-body. Snail generation times will decrease in most areas, meaning that snail populations will recover faster from natural population reductions and from snail-control efforts. We suggest a link between the ecological properties of transmission sites and infection risk which could significantly affect the outcomes of interventions designed to alter water contact behaviour – proposing that such interventions are more likely to reduce infection levels at river locations than lakes, where infection risk remains high for longer. In cooler areas where snails are currently found, increasing temperatures may significantly increase infection risk, potentially leading to new, high-intensity foci of infection. Citation: McCreesh N, Booth M (2014) The Effect of Increasing Water Temperatures on Schistosoma mansoni Transmission and Biomphalaria pfeifferi Population Dynamics: An Agent-Based Modelling Study. PLoS ONE 9(7): e101462. doi:10.1371/journal.pone. 0101462 Editor: Ulrike Gertrud Munderloh, University of Minnesota, United States of America Received March 21, 2014; Accepted June 6, 2014; Published July 2, 2014 Copyright: 2014 McCreesh, Booth. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Funding: The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement no. 266327. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * Email: Nicky.mccreesh@durham.ac. uk