Article Index Head Lice Information Page 2 Page 3 Page 2 of 3 Nature and Incidence of Head Lice   HEAD LICE also called, Pediculus Humanus Capitis are small blood-sucking, wingless insects found on the human scalp. They are approximately the size of a sesame seed (1) and cannot jump or fly.  They are six legged creatures with claws, which help them cling to and crawl through human hair.  Head Lice origins date back to the origin of human life. Their survival needs necessitate spending their whole life cycle on a human host. They live by feeding off their human host by piercing their scalp with its mouthpart to draw out the blood.  Head to head contact with an infested person remains the most widely respected scientific view of how head lice are spread from one host to another. There are conflicting views amongst scientist as to whether lice can spread through sharing pillows, hats or combs. Occurrence of Head Lice Any person can be infested with head lice irrespective of age, gender or class. They are equally attracted to clean and dirty hair.  Head Lice are most commonly found in school children, the most vulnerable age for catching head lice infestation remains 4-11 years. Life Cycle of a Head Louse   The life cycle of a head louse can be classified in three distinctive stages, egg, nymph and mature lice. Louse eggs: This is the first stage in the life cycle of a head louse. Louse eggs are usually laid at the base of hairs, about ½ -inch from the scalp (2), where they hatch after 7-10 days.  They can camouflage their presence by blending with the hair colour. A female louse can lay as many as five to six eggs each day.  The eggs attach to the human hair with a material like super glue, which makes it difficult to remove these eggs.     Image: Viable egg on a hair shaft Source: MEC at Cambridge (6)   The nymph: Lice eggs usually hatch within 7-10 days. Hatched eggs are called nymphs. They are similar to an adult louse in characteristics but they differ in size. Nymphs are much smaller than a mature louse. Nymphs moult three times before becoming a mature head louse. This process takes 9-12 days.  Mature head lice: An adult head louse is approximately the size of a sesame seed (1) and can lay as many as 50-100 eggs in its lifetime. Head Lice feed on human blood, making humans indispensable to their survival. Head Lice cannot survive for more than 2 days if they fall off their human host (3).     Image: Egg and Louse on A Hair Shaft Source: MEC at Cambridge (6)    Nits: The empty egg-shell is called a nit and remains firmly glued to the hair. They are snowy white in colour. They cannot be easily brushed out and can sometimes be confused with dandruff (4). Image: Nit on hair shaft Source: MEC at Cambridge (6)    Detection of Head Lice   The presence of head lice can be  signalled by itching in response to bites which instigates continuous head scratching that can be a symptom of head lice infestation.  Visual evidence can be through the presence of lice, eggs or nits (empty eggshells) in human hair. Behind the ears or at the nape of neck are the favourite places for head lice to appear. ‘Detection combing’ with a fine toothed plastic comb remains one of the most effective methods for detection of head lice. One detected, the comb can also be used for removal of lice. It remains extremely important to use a comb with optimum teeth spacing that allows no space for lice to escape and hence makes the detection and removal, a hassle free and quick process. << Prev - Next >>