As you might know, lice are little — about the size of a sesame seed — and can be white, brown, gray, or dark gray. They're most common around the ears and the back of the neck, and feed off of human blood. Nits are much more noticeable on darker-colored hair but lice is more noticeable on lighter hair.  The most common symptom of head lice is itchiness in and around the back of the neck. In many children, lice don't produce any symptoms until weeks or months after they've moved in. For this reason, it's important to do regular visual check-ups with a fine-toothed comb in order to spot an infestation as early as possible.  Doctors recommend combing for lice after the child has taken a bath/shower, while their hair is still wet. Because head lice commonly affect young children in school, it's important to be vigilant about situations in which children may share certain objects. Although you probably want to encourage your children to share certain things, you probably want to discourage them from sharing the following:  Hats Headbands Hair accessories Pillows Combs Any other objects that promote direct head-to-head contact between a carrier and potential carrier. Obviously, although lice are irksome, they're not to be avoided like an infectious disease. Instead, be aware of anyone who may have had lice or is being treated. Knowledge is power. If somebody had lice and was treated, but it has not been two weeks since their treatment, make sure you try to avoid contact with any of their fabrics. You don't have to be afraid of them, but casually avoid situations which involve contact with them, especially head-to-head contact. Lice can commonly occur in schools or summer camps. If your school or camp doesn't give out regular checks, ask the nurse for one every once in a while. If the nurse is unavailable, schedule an appointment with your child's general practitioner to check for lice. Lice is especially common among elementary aged children during winter.

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Write a summary of the previous text in Vietnamese:
Nhận biết triệu chứng. Nói với trẻ rằng điều quan trọng là không nên dùng chung một số đồ dùng với người khác. Chú ý tới người đang bị chấy rận. Kiểm tra tóc.