SACO — A case of chickenpox has been confirmed at Thornton Academy.

School administrators sent an email to parents on Friday that one case of chicken pox had been confirmed at the high school.

Thornton Academy is a private school in Saco with a middle school and a high school. The high school provides education to publicly-funded students from Saco, Dayton and Arundel and private pay students from surrounding communities and across the globe.

Chickenpox is an infection caused by the varicella-zoster virus.

Chickenpox can be spread for one to two days before the rash starts, advised school officials in the letter to parents. It is contagious until all blisters are crusted. After being in contact with the chickenpox virus, it takes 14 to 21 days before the rash appears.

Thornton Academy officials advise parents that if someone in the household develops symptoms resembling chickenpox to contact their health provider, report the illness to the school nurse and avoid contact with others who have not had chickenpox or who are not vaccinated until lesions become crusted.

“This means staying at home from school, daycare, work, and other school activities,” school officials wrote in the letter to parents.

According to the Maine Center for Disease Control, the best way to prevent chickenpox is to get the varicella vaccine. A regimen of two doses of the vaccine is 90 percent effective in preventing the virus, according to the Maine CDC.

State law requires students enrolled in Kindergarten through 12th grade to have one dose of the varicella vaccine.

Parents can get exemptions for vaccinations for their children due to violations in religious or philosophical beliefs. They can also get exemptions for vaccinations if they provide a written statement that their child will get immunized within 90 days of enrolling in school, written consent for a public health officer or other health care provider acting as an agent of the school to provide an immunization, or a statement from a doctor that immunization is inadvisable.

There were 198 outbreaks of chickenpox in Maine in 2017, according to data from the Maine CDC. Five percent of these cases were associated with an outbreak and 20 percent of these cases were in students from Kindergarten through twelfth grade.

— Staff Writer Liz Gotthelf can be reached at 780-9015 or by email at egotthelf@journaltribune.com.