Autistic children constitute the district's fastest growing population of special education students, growing 2,398 percent since 1996 -- from 83 autistic students then to 1,990 last year. The district's overall enrollment grew 72 percent in the same time period.

Autism, which predominantly affects boys, is a developmental disability that curtails a person's ability to communicate and interact socially. It's considered the second-most serious developmental disability after mental retardation, but is also known as a "spectrum disorder" because it affects people differently and to different degrees.

On Friday, the state Board of Education provided the district some help when it voted to provide extra funding to offset the salaries of 181/2 teacher positions for autism programs. Clark County got $38,763 per position, which will pay for roughly more than half of an average annual salary for a special education teacher.

The school district wanted salary help for up to 26 teachers, but Charlene Green, deputy superintendent for student support services, was not surprised by the lesser funding.

"We never get the full amount we ask for," she said.

The state board is distributing discretionary funds for special education programs across Nevada, and the Clark County district is trying to increase funding to reduce class sizes and add more programs for autistic children.

By law, class sizes for autistic children are limited to eight or fewer for grades K-6, but a recent review by Rutgers University suggested the district keep such classes at two or three students per teacher.

But high teacher turnover and high demand for special education teachers make it difficult to fill vacancies, school officials said.

"This is really a national problem," said Martha Tittle, the human resources director for Clark County.

The growth in the school district's autism population is just a microcosm of what many consider to be an epidemic. A 2007 study by the Centers for Disease Control reported that autism now affects one in 150 children, and one in 94 boys.

Scientists are studying genetic neurological disorders as well as environmental factors since they don't think changes in diagnosis can alone explain the growth in autism, said Carin Yavorcik, a spokeswoman for the Autism Society of America.

Clark County has a shortage of special education teachers and other professionals, with 168 vacancies for classroom instructors and 115 openings for specialists such as speech therapists and psychologists.

The school district is trying to fill high demand jobs with programs to assist professionals with college degrees in transitioning to teaching.

And it continues to recruit nationally. District recruiters will travel this month to a job fair in Dallas, where the local school district has laid off a thousand teachers.

Although parent and vice principal Yocum understands the district's challenge, he remains concerned.

"I've been told many times the Clark County School District is doing the best they can to staff autism programs," he said.

"I'm wondering if the best we can do is the best for our kids."

Contact reporter James Haug at jhaug@reviewjournal.com or 702-799-2922.