Lice

Introduction

Lice are tiny insects that live on humans and survive by feeding on blood. Lice infestation is transmitted person-to-person and via intimate objects that tend to be shared

Causes

You can get lice by coming into contact with either lice or their eggs. Eggs hatch in about one week. Lice can't fly or walk on the ground.
Head lice are transmitted mainly through head-to-head contact (sharing pillows, lying on carpet, wearing someone's hat).
Body lice are transmitted by direct contact with an infected person.  Body lice are frequently seen among the homeless and others living in overcrowded conditions, where clothes are not washed often and where overall cleanliness is lacking.
Sharing items. These may include clothing, headphones, brushes, combs, hair decorations, towels, blankets, pillows and stuffed toys.
Contact with contaminated furniture. Lying on a bed, sitting in furniture or even using a toilet seat recently used by someone infected with lice can spread them. Head lice live for up to two days off the body.
 

Symptoms

The most common symptom of lice infestation is itching in the affected areas. Symptoms vary depending on which type of lice is present.
Head lice may not cause any symptoms early in the infestation. Itching on the scalp may develop weeks or even months after lice have infested the person. Scratching infested areas can make the skin raw. The raw skin may weep clear fluid or crust over, and it may become infected.
Pubic lice cause severe itching of affected areas. Their bites may cause small bruise-like marks on the torso, thighs, or upper arms. Pubic lice most often affect the genitals, but they may also appear in the areas around the anus and armpits, in body and facial hair, and on the eyelashes.
Body lice cause intense itching, especially at night. Itchy sores appear in the armpits and on the waist, trunk, and other areas where seams of clothes press against the skin. The lice and eggs  may be found in the seams of the person's clothing but are generally not seen on the skin.

Treatment

Lice and their eggs must be destroyed to get rid of an infestation. The most common treatment is a topical nonprescription or prescription cream, lotion, or shampoo to kill the lice and eggs. Doctors usually recommend a product containing permethrin (called Nix). Permethrin is a synthetic form of pyrethrin, which is derived from chrysanthemums. Other commonly used brands contain pyrethrin in combination with piperonyl butoxide; brand names include A200, Pronto, and Rid.