Hi & Welcome. Based on the history given in your query, the 4 years old girl seems to be suffering from Pinworm infestations. The most common symptom of pinworms is itching around the anus. It is worse at night when the female worm deposits her eggs on the person infected. This can lead to difficulty getting a good night s sleep. 1. The common name is Pinworms infestation or enterobiasis. 2. It is diagnosed by identifying the eggs of pinworm in the stool or Cell tape which should be applied around the anus overnight and removed in the morning. 3. This is a highly contagious disease, when people who are infected touch their anus, the eggs attach to their fingertips. They can spread the eggs to others directly through their hands, or through contaminated clothing, bedding, food, or other articles. The eggs can live on household surfaces for up to 2 weeks. 4. These are small parasites that can live in the colon and called as Pinworms (Enterobius vermicularis). For such cases I usually prescribe a single oral dose (tablet or suspension) of Albendazole which kills the worms. This is to repeated after 2 weeks to prevent re-infection. Besides, you must see it to that the following preventive measures are followed like: 1. Washing the hands before eating or preparing meals helps prevent spread of infection. 2. Avoid scratching the anal region. 3. Avoid biting the fingernails. 4. Keep fingernails short and clean. 5. Wash all bedding and pajamas regularly. 6. Be sure your child changes underwear daily. 7. Thoroughly launder all bedding, clothing, and toys to destroy any lingering eggs and 8. All the family members should also be treated with a single dose of Albendazole. Hope these answer your query.