Fleas are a nuisance, but that’s not the only reason to take a flea infestation seriously: Fleas can transmit diseases and even cause tapeworms.Getting rid of your cat’s fleas means more than just getting rid of the fleas on your cat. You need to treat your cat’s interior surroundings (i.e. your home’s surfaces, nooks and crannies) and then you need to treat the source, which usually means your home’s surrounding yard.On your cat: Using a fine-toothed flea comb, give your cat a long and thorough brushing. In between strokes, dip the comb in a bowl of soapy water to kill the fleas and eggs. Keep combing until you’re no longer collecting any fleas or eggs. Shampoo your cat in warm water using any shampoo, whether or not it’s specially designed for flea control. Soap alone works as a highly effective flea insecticide.