Whether your cows stand in a cooling pond, or in a puddle from a sudden downpour, the water can help Leptospirosis hardjo spread from cow to cow, says noted Lepto expert Carole Bolin, of Michigan State University. If you have a cow infected with L. hardjo and she urinates while standing in water, other cows standing near her could become infected. Urine is a reservoir for L. hardjo.