Chicken pox was once considered a rite of passage for most children. In fact, before the chicken pox vaccine became available, about 4 million children in the Unites States contracted the illness each year.  But what exactly is chicken pox? Infection caused by bacteria or virus? And what causes it?

What is chicken pox? 
Chicken pox (also known as varicella, herpes zoster or postherpatic neuralgia) is a highly contagious and infectious viral infection.  Once you catch chickenpox, the virus usually stays in the body forever. Although you will probably not manifest symptoms chickenpox twice, the virus can also cause shingles.

Stages of chicken pox
The chickenpox rash occurs in three stages. It is possible for all three stages of chicken pox to occur at once. The three stages of chicken pox are:

1. Raised pink or red bumps (papules)
2. Fluid-filled blisters (vesicles)
3. Vesicles crust over and scab

People diagnosed with varicella can spread infection from 1-2 days prior to the onset raised bumps on the skin until the last lesion has crusted and all blisters have formed scabs(approximately six days later). The incubation period, or the time interval between initial infection and the appearance of the signs and symptoms of chicken pox, is 10 to 21 days, most often somewhere around 14 days.

What causes chicken pox? Plus, who is at risk and how does the virus spread?  More on chicken pox cuases, transmission and risk factors in the next section on causes of the chicken pox virus here.