Pediculus Capitis



Pediculus Capitis is the infestation of which reside on the scalp and hair shaft. Pediculus Capitis can be referred to as head lice or informally as cooties. These are little but visible organisms that live on the human scalp. These tiny parasites survive by feeding from human, getting their nutrients from sucking human blood for 4 to 5 times a day. Their way of sucking blood can irritate and cause discomfort by way of itching to the scalp. This itching can be especially uncomfortable at night during sleeping. Patients affected by pediculus capitis do not experience itching immediately but they usually feel the symptoms after a period of four to six weeks.

Head lice can spread easily from one infected person to another non-infected person through head to head contact, and also head through comb sharing, bed linen, clothes and towels etcetera. The spread of head lice is very common with children in schools. Pediculus Capitis is not a life threatening, but causes great discomfort and sometimes can secondary infections to the scalp due to excessive scratching.

Life cycle and morphology

 The life cycle of a head louse begins with an egg, which is referred to as a nit. Nits are produced and laid by a female head louse after mating with a male member of the species. These nits are laid in a group of 3 to 4 eggs per day. The eggs have an oval shape of around 0.8mm length and they are laid close to the scalp where they can get the right temperature for development. The female head louse releases some form of glue like substance, which attaches the nit to the hair shaft.

Nymphs are the second stage in the life cycle; they hatch from the eggs as immature head lice. The growth of a head louse can take 12 to 24 days depending with the blood supply. An adult head louse can grow to a size of almost 2 to 3mm long.  They have a lifespan of up to thirty days. Head lice cannot survive for more than three days out of its host.Head lice have no wings, so they neither fly nor jump. Head lice usually prefer to dwell in darker areas where there is less light like nape of the neck or behind ears.The colour of head lice could depend on the environment they resides on, but in most cases they are grey in colour.


Pediculus Capitis has grown to be a worldwide concern, since the 1960s. The numbers has risen to millions per year affecting mainly children between the ages of 3 to 13 years.  There was at least one outbreak reported by 80% of American primary schools affected by head lice in 1997. This was a higher incidence rating than chicken pox in children. In United States as whole, the estimate is that 6-12 million children receive treatments every year for lice infestation. Girls in general, are infected more frequently than boys, perhaps as consequence of keeping longer hair.

African Americans are the least affected in the United States. The condition of head lice is not common in afroid hair due to the texture and density of the hair. In certain parts of Africa all manner of lice are known to spread diseases, namely typhus. In the case of typhus the louse acts as a vector, which defines a larger organisms that commonly carries and transmits a smaller disease causing organisms, which is Rickettsia bacteria in typhus. Typhus kills 10 to 60% of those affected without treatment.

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