Immunotoxicity of surface waters contaminated by municipal effluents to the snail Lymnaea stagnalis

► Urban effluent induces inflammation in Lymnaea stagnalis. ► Bacterial load of urban effluent impairs the pond snail immune response. ► Xenobiotic loads contributed to immunomodulation. ► mRNA expression of genes involved in immune response was modified by contaminated waters. ► mRNA expression of TLR4 gene seemed modulated by xenobiotics present in the effluent.