Severe leptospirosis infections are sometimes called Weil's disease. The symptoms of a severe infection usually develop one to three days after the more mild symptoms have passed. If the condition progresses to a severe infection, it may affect organs, including the brain, liver, kidneys, heart and lungs.evere leptospirosis infections are sometimes called Weil's disease. The symptoms of a severe infection usually develop one to three days after the more mild symptoms have passed. If the condition progresses to a severe infection, it may affect organs, including the brain, liver, kidneys, heart and lungs.