A substitute teacher at Lake Anne Elementary School in Reston said yesterday that she has been hospitalized with viral meningitis, bringing to four the number of cases in the Fairfax County school system this month.

Carrie Kleeb, 33, of Leesburg said she was scheduled to be released yesterday afternoon from St. Mary's Hospital, where she had been confined to bed rest for a week and had two spinal taps.

Health officials in Virginia and Maryland said they could not confirm her case, citing patient confidentiality laws.

A 16-year-old student at Chantilly High School died of the disease June 17. Another student at the school was hospitalized, as was a teacher at Armstrong Elementary School in Reston. Infectious disease specialists have been unable to pinpoint the virus that killed Courtney "Kay" Richard and sickened the others or determine whether there is any link between the students at Chantilly and the teacher in Reston, eight miles apart.

Kimberly Cordero, a spokeswoman for the Fairfax County Health Department, said yesterday that she was not sure whether Fairfax officials have investigated Kleeb's case. She said there could be other cases that have not been publicized because doctors do not have to report viral meningitis to public health officials, only the more serious and often fatal bacterial meningitis.

Meningitis cases frequently emerge during the summer, when people gather in parks and pools, often sharing such things as water bottles and lip balm, Cordero said. She said the public should not be alarmed when a handful of cases emerge.

"With a [Fairfax County] population of 1 million, we'd have to see many cases -- more than 120 -- for this to be unusual," she said. "It was unusual for someone to pass away. . . . There's a highlighted interest."

Kleeb was a student teacher at Lake Anne until last winter and then became a regular substitute teacher, mostly in kindergarten and third grade, until June 11. On June 12, she left for a weeklong trip to the Dominican Republic, where she volunteered at a large orphanage with about 40 other Americans.

A few days into her trip, Kleeb said, she and two other volunteers experienced intense headaches and nausea. They soon felt better and returned to work. She flew back to the United States on June 19. The next day, she visited a relative on Solomons Island, Md. A few hours into her stay, she began getting severe headaches and chills.

"I tried to sleep it off, but every time I tried to get up, it hurt even more," she said in a telephone interview from her hospital room. "I thought I had a parasite, or that something bit me."

On June 21, she was admitted to St. Mary's Hospital, and a spinal tap indicated that her white blood cell count was about 20 times as high as normal, meaning that her body "was definitely fighting a viral infection," she said. Doctors diagnosed viral meningitis, an infection of the tissue surrounding the brain and spinal cord.

"I was just scared," she said. "It's just hard to get comfortable. I spent a lot of time with the cover over my head just wanting complete darkness."

The teacher for whom Kleeb substituted, Kathy Magielnicki, said Kleeb's father called her Friday to advise her of the viral meningitis diagnosis. Magielnicki said she spoke with Kleeb, then reported the news to the school secretary, who called local health officials.

Kleeb said she was visited by health department officials but was not sure whether they were from Maryland or Virginia.

Citing patient confidentiality rules, John Hammond, a spokesman for the Maryland Department of Health and Mental Hygiene, said he could not discuss individual cases. "If there's anything going on that would affect public health, we would certainly communicate that message," he said.

Virginia and Fairfax County health officials have spoken frequently about the other three cases ever since some parents and at least one school official complained about the lack of information they were getting about the two cases of viral meningitis at Chantilly High School. Many parents said they heard the news long before the school system announced it, through the PTA or other students and parents. Chantilly High Principal Tammy Turner said that until the day Kay Richard died, "We had no notification. We really had no idea what she was ill from."

Gloria Addo-Ayensu, Fairfax County's health director, held a news conference June 21 after receiving several phone calls from concerned residents.