After several children who attend a local elementary school contracted chicken pox, the Southern Nevada Health District is reminding residents, especially parents, that there is a vaccine to prevent the illness.

Additionally, the Health District officials are urging parents to get a second dose of the varicella vaccine for their children, based on a new recommendation from the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices.

The initial vaccine is provided to children 12 to 15 months old.

The second vaccine is recommended for children ages 4 to 6.

Older children and adults also are encouraged to get both doses, said Brian Labus, a Health District epidemiologist.

"This is kind of what we expected to see in a population that has had one dose of the vaccine,'' Labus said about the outbreak.

"The vaccine does not work all the time," he said. "The CDC recently recommended a second dose for school-aged children. That second dose is so that kids won't get sick at all.''

The school attended by the children who fell ill is Eisenberg Elementary School, at Gowan Road and Rampart Boulevard in the northwest valley, said Diana Taylor, the Clark County School District's director of health services.

Labus said all Southern Nevadans who have not had chicken pox or the vaccine are at risk.

Chicken pox is considered a highly contagious viral disease that is spread through direct contact with someone infected.

An exposed person who has not had chicken pox or the initial vaccine has a 70 percent to 80 percent chance of contracting the disease.

Although the disease is generally mild, it can cause serious complications or even death in adults or children with weakened immune systems due to another illness.

Symptoms usually appear within three weeks of exposure and may include mild fever and itchy blisters on the scalp, face and torso.

Under Nevada law, any child who attends school or a day care center must receive childhood vaccines before being admitted.

Labus said the children infected with chicken pox at the elementary school had received the initial varicella vaccine.

A school nurse in the Clark County School District notified the Health District about the outbreak, Labus said.

Review-Journal writer Antonio Planas contributed to this report.