Are there any advantages to having a disease?

Does flash photography harm baby's eyesight? What is ocular myasthenia gravis? Can having a disease give you an advantage against another disease? Why are soldiers so prone to PTSD? Why is it so difficult to predict the weather? What does it mean to be double-jointed? Are we susceptible to certain rhythms? Why is water so important? Like this podcast? Please help us by supporting the Naked Scientists