Organism, Causative Agent, or Etiologic Agent
Chicken pox is caused by the varicella-zoster virus, VZV, a member of the Herpesvirus group.
Chicken pox is spread by coughing and sneezing (highly contagious), by direct contact, and by aerosolization of virus from skin lesions. The skin lesions of chicken pox and shingles (zoster) can cause chicken pox in a susceptible person, but will not cause shingles.
A skin rash of itchy, blister-like lesions, covering the body but usually more concentrated on the face, scalp, and trunk. Most, but not all, infected individuals have fever, which develops just before or when the rash appears. If exposed, persons who have been vaccinated against the disease may get a milder illness, with less severe rash (sometimes involving only a few red bumps that look similar to insect bites) and mild or no fever. Adolescents and adults are more at risk for severe disease. Women infected during pregnancy may pass the disease on to their baby.
Varicella vaccine can prevent this disease. Currently, two doses of vaccine are recommended for children, adolescents, and adults.
School Exclusion Policy
Children with suspected or confirmed chickenpox (varicella) should be kept out of school or childcare until the lesions are dry (scabbed) or if lesions are not vesicular (blister-like), until 24 hours have passed with no new lesions. Rules for exclusion of sick children from school and childcare are outlined in the Texas Administrative Code, specifically Rule 97.7 for schools and Rule 746.3603 for childcare.
Recent Texas Trends
Texas’ varicella incidence dropped dramatically in 1999, as vaccination coverage rose across the state due to school vaccine requirements. Rates have continued to decline, and in 2012, there were 2,410 cases of varicella in Texas, the lowest since the year reporting began. The biggest decrease has been seen in the age group most heavily affected by varicella, five to nine year olds.