When kittens leave the nest, we have to assume that they are infected with worms (through the mother). These worms are hardly ever visible unless the kitten is very heavily infected. Therefore deworming cures are absolutely necessary. Besides, cats that go outside are a risk factor: rinsing worm eggs can be found in every clod of soil. Always assume an infection or risk of infection.
Many cat owners think that keeping their cats inside protects them from parasite infestations and/or diseases. Unfortunately, that’s not always accurate. Indoor cats can become infested with fleas quite simply. Your cat can get tapeworms by eating a flea that is carrying tapeworms.
Internal parasites can cause diarrhea, weight loss, stern hair coat, and/or a pot-bellied look. Vomiting can also be seen, sometimes with worms in the vomit. Sometimes cats with internal parasites show no signs at all.