Article in English: Roundworms can block your intestines because they are usually thick, and in some cases can grow to be the size of a pencil. When your intestines become blocked, you can develop extreme abdominal pain. You may feel: A pain in your stomach, like that of a cramp that won’t seem to go away. Roundworms can lay eggs that leak toxins into your body. These toxins can release into your system and may cause your anus to become itchy. This itchiness can get worse at night because the worms tend to lay their eggs at night while you are resting. When roundworms multiply, they may start to leave your body to find a different host. This means they start to exit your body through different orifices. The most common ways for roundworm to exit is through the:  Mouth. Nose. Anus.

Summary in Chinese:
当心出现严重的腹痛。 肛门周围感到瘙痒时，你要加强警惕。 如果你擤鼻涕或排便时看到了蛔虫，立即去医院进行治疗。