Lice affect people from all socioeconomic backgrounds and ages. Children are particularly prone to head lice infestations due to frequent, close contact with others. Lice are parasitic, highly contagious insects and are easy to miss in scalp inspections without the proper training. They are usually found near the scalp, but have been known to infect eyebrows, eyelashes and pubic hair. Lice eggs differ from nits in that a louse egg contains an unhatched embryo, while a nit is a hatched louse egg shell.

Color

Unhatched lice eggs are light-colored when they are first laid--yellow-tinted or grey. Right before hatching, they turn darker shades of tan, sometimes described as "coffee colored." After they hatch (and become nits), they appear white. Other than color, it is virtually impossible to tell the difference between a nit and a louse egg without a microscope.

Transmission

As lice eggs contain live embryos that may hatch, transmission from lice eggs are possible. As nits do not contain any component or material that can produce a live louse, transmission from nits is not possible. However, both nits and eggs usually stay glued to the hair shaft of the person infected. Infestation usually occurs through the transference of live adults.

Diagnosis of Infestation

Upon close inspection, nits are more likely to be mistaken for dandruff than unhatched eggs, due to their white color. This can lead to annoying misdiagnoses in either direction, even by trained professionals. Parents or caregivers told their children have lice, when all they really have is a case of dandruff (a "false positive"), go through an unnecessary house and scalp treatment regimen. On the other hand, misdiagnoses in the other direction--failing to diagnose lice infestation when one is present (a "false negative")--may be worse. Lice do not carry disease but can cause intense itching and scratching that can eventually lead to infections.

Treatment

Technically, nits (unlike eggs) do not require treatment, as they are only egg shells. Like unhatched eggs, however, they need to be combed out of the hair with a special comb, as the "glue" lice use is notoriously strong and resistant to shampoos and treatments. Treatment methods do not differ much, however; whether nits or eggs are identified, it is likely there are viable eggs, nits and adults by the time the infestation is caught. Additionally, the smallest, most immature lice are hardly distinguishable from eggs, making diagnoses even harder. Most doctors play it safe and treat for all stages of the louse life cycle.

Terminology

The terms "louse egg" and "nit" are often used interchangeably (although incorrectly) in medical literature, so keep this in mind when reading brochures and treatment instructions.

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