Fifth disease, a mild viral disease that can produce a bright red rash on the cheeks of those who contract it, may have been the cause of irritations experienced by students evacuated from Riverton Elementary School in February.

"Of all the theories we looked at, it (Fifth disease) is one we could not eliminate for the rashes that clustered around Feb. 24. It's plausible it was the cause, but it cannot be proven," said Dr. Cynthia Lewis-Younger, assistant professor of occupational medicine at the University of Utah and a member of an expert panel assembled to study medical and scientific data associated with the school. The panel's results were discussed during a meeting Thursday evening in Oquirrh Hills Elementary School.The district school board ordered the 3-year-old school closed Feb. 26 until officials could determine why students and staff were occasionally sickened in the building.

A parent advisory committee empaneled after the closure will ask the Jordan District Board of Education to reopen it if a checklist of requests is met.

Half of the items on the list have been achieved, said Leon Berrett, committee chairman.

"With all the time and effort put into this, we really feel this is going to be one of the safest schools in the state," Berrett said.

The school board will act on the recommendations at 6 p.m. Tuesday, July 14.

The medical experts reported that two days before the school was closed, 18 students were taken to an area hospital complaining of rashes, headaches and respiratory irritations.

Twenty-six students who developed rashes on or within two weeks of Feb. 24 underwent blood tests to determine if they carry antibodies that suggest either exposure to the virus or the active disease.

Sixteen children tested positive for antibodies that indicate that at some time during their lives they have been exposed to the virus that causes Fifth disease. One child's results suggested a recent infection from the virus. It causes a "slapped-cheek" appearance for one to three days, followed by a pink lacelike rash, mainly on the thighs and upper arms.

The lacy rash comes and goes for one to three weeks. The disease has few other symptoms other than a slight runny nose and sore throat. Complications are rare.

Lewis-Younger said medical studies suggest 60 percent of 20-year-olds are exposed to Fifth disease during their lifetime. Specific exposure rates for Salt Lake County have not been determined.

Lewis-Younger, a physician who also holds a master's degree in public health, said medical personnel who treated students transported to the hospital Feb. 24 also were interviewed regarding their observations and care.

In only five of 19 cases did physicians verify the presence of rashes, she said. Some students had scratch marks, "but that's a little bit different from a rash."

None of the students treated was deemed "seriously ill," she said. "Only one received treatment and none required additional treatment to the best of my knowl-edge."

A Jordan School District nurse reported five of 15 children she examined had rashes. At the time, she also suspected Fifth disease.

The rashes are not consistent with exposure to hydrogen sulfide, a gas produced in sewer systems, she said. Monitoring devices did not detect the presence of the sewer gas, but a report compiled by the expert panel notes "the sulfide meter is not as sensitive as the human nose in detecting hydrogen sulfide."

As for chronic problems reported by some students and teachers since the school opened in 1995, experts believe some of the problems may be attributed to "chronic exposure to unpleasant odors."

"Because the detection of odors can activate other parts of the brain that can result in symptoms such as nausea, odor-related physiologic symptoms could have resulted," the report said.

"Some individuals can perceive the odors at very low levels and may respond with symptoms, but on the information we have about those symptoms, these effects are expected to subside over time with continued removal from exposure," the report read.

The expert panel reported that the events of Feb. 24 were likely a culmination of unresolved complaints over perceived building problems from parents and teachers.

Ken White, vice president of industrial hygiene for IHI Environmental, also a contract consultant for the school district, said, "Springs are getting wound tighter and tighter with this thing."

The report said, "Symptoms such as rash, itching, headaches and sore throats may have been compounded by stress and anxiety that arose from the initial concern by teachers and parents and later by the arrival of emergency vehicles and the appearance of fire and emergency personnel in the school. Many teachers and parents interviewed spoke of a progression of concern, anxiety, fear and `ultimately chaos' as the day progressed."

Early on, parents and some teachers suspected sewer odors as the cause of the problem.

Work is under way to segregate sewer lines at the school, sending waste from the school kitchen to one line and wastewater to another.

The project also includes shoring up sags in sewer lines and installing devices that will automatically flush toilets to create a constant outflow of wastewater. The intent is to help eliminate sewer gases. Chemicals will be added to the waste systems that inhibit the production of sewer gases, said Robert Day, assistant superintendent of auxiliary services for the Jordan School District.

The expert panel also recommended engineering modifications to the sewer system.

"Unless the sewer system odor problem is solved, a recurrence of symptoms and complaints by future building occupants is possible," the report read.