MedicineNet.com and Healthline.com show pictures of head lice, nymphs and eggs, both as close-ups and on the scalp and hair. The website of the American Academy of Dermatology shows a video and step-by-step instructions detailing how to find and remove head lice.
Head lice are parasites that feed on blood and attach themselves to hair shafts, including the eyebrows and eyelashes, reports Healthline. Immature head lice are called nymphs, hatching from the eggs and moving closer to the scalp to feed. They mature after nine to 12 days. An adult louse measures 2 to 3 millimeters and lives for one month on average, although it dies within one to two days if it does not have access to food.
While itching is a common sign of infestation, the only reliable indication is the presence of a louse or nymph, states MedicineNet. Some people are asymptomatic and do not itch, while others develop an allergic reaction and find their necks and scalps inflamed. If there is a rash, the breakdown of the skin and the itching increase the risk of developing a bacterial infection and may require antibiotics.
A topical shampoo and a fine-toothed comb are usually sufficient to treat a lice infestation, but bedding and clothing must also be laundered to avoid reinfestation, according to MedicineNet.