SAN DIEGO, CA: Six students at a San Diego-area charter school have come down with the chickenpox in recent weeks, county health officials said Friday, bringing the total to 16 reported cases of the illness in San Diego County thus far in 2016.

The first affected student at San Diego Cooperative Charter School's Linda Vista campus reported the illness on March 7, according to the San Diego County Health and Human Services Agency. The latest student to be diagnosed began experiencing symptoms on Wednesday. Chickenpox — a highly contagious disease caused by the varicella virus — is easily spread by coughing, sneezing or being in contact with chickenpox blisters.

The diagnosed students are between 5 and 8 years old. One child received the age-appropriate recommended dose of the varicella vaccine, while the other five children were not immunized, according to county health officials. "Chickenpox is a preventable disease," said Dr. Wilma Wooten, county public health officer. "By having their children immunized with the recommended two doses of the vaccine, parents can help their children avoid chickenpox and prevent it from spreading to others, especially to those who are unable to be vaccinated due to serious medical conditions, and who could become very ill if infected with chickenpox."

The incubation period for chickenpox is generally 14 to 16 days from exposure, with a range of 10-21 days, so additional cases may be reported through May 11, health officials said. The school notified students and staff about the outbreak, as well as the staff at their Mountain View campus because students and staff travel between the two locations.

Chickenpox is not reportable to the county public health department unless it occurs in an outbreak or results in a hospitalization or death.

Symptoms include a skin rash of blister-like lesions, covering the body but usually more concentrated on the face, scalp and trunk. The risk of complications increases after puberty and includes bacterial infection of skin lesions, dehydration and pneumonia, health officials said.

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 and mild or no fever. The illness lasts about 5-10 days. The Centers for Disease Control and Prevention recommends two doses of chickenpox vaccine. Children should be vaccinated at 12-15 months of age and receive the second dose at 4-6 years of age, according to the CDC.