Karen Perez, a fourth-grader at El Monte Elementary School in Concord, was otherwise healthy with no known medical conditions that would complicate her recovery, according to Contra Costa County school and health officials.

She died May 29 but the state wasn't able to confirm that she had swine flu until Wednesday. She had a secondary bacterial infection and officials haven't yet determined whether her death was the result of swine flu, said Dr. Wendel Brunner, Contra Costa County's Public Health director.

The swine flu - a strain of influenza Type A, subtype H1N1 - has mostly been mild in the United States, and the vast majority of those infected have fully recovered with no medical intervention. However, the virus has killed at least 17 people in the United States since the outbreak became a public health concern in April. The Concord girl was the first child with the disease to die in California.

"Tragically, in this case, this child did not recover," Brunner said during a news conference Thursday.

The principal at El Monte Elementary School left automatic voice mail messages with parents Thursday afternoon informing them of the girl's death and the relation to swine flu, said Richard Nicoll, interim superintendent for the Mount Diablo Unified School District.

School to remain open

The county will not be closing the school. Karen had been taken out of class at the first sign of illness and had not been in school for the past seven days. Anyone who might have been infected by her at school would have become ill by now, Brunner said.

He also noted that with 90 confirmed or probable cases in Contra Costa County - and undoubtedly hundreds more cases that have not been identified - the virus is already widespread in the community and closing one school won't contain swine flu.

"We know that the swine flu virus is throughout the county. There are infections in many of the schools, and we're trying to encourage people to keep their kids out of school until they're completely well for seven days, to slow down transmission of the virus," Brunner said. "The fact is, this death was terribly tragic, but it doesn't indicate any increased risk for other children."

Still, parents with children at El Monte Elementary School said Thursday they were worried after hearing of the young girl's death and wondered if it wouldn't make sense to close the school until authorities determine exactly how she died.

Rima Mojadidi, 32, has two children at El Monte, including a son, Samim, who was in Karen's fourth-grade class. Mojadidi said the school sent a letter to parents on Monday informing them that a child at the school had been sick.

After hearing that Karen had died, she questioned whether the school should stay open.

"Of course I'm scared," Mojadidi said. "They shouldn't have kids going to school until they find that every child is safe and OK."

Public health knows best

Nicoll, the interim superintendent, said he trusts the public health department to know best how to protect the children at El Monte and other elementary schools. Early in the swine flu outbreak, the county recommended that schools close if a student was infected, but since early May, as the virus spread widely across the state and country, public health experts agreed that closing schools wasn't helping contain the disease.

"We're not experts in public health," Nicoll said. "When they told us previously to close schools, we did it, but now they're saying there's absolutely no reason to do that. There's absolutely no health risk to students, is what we've been told."

Brunner pointed out that, as terrible as it is that a child has died, county public health officials had expected that at some point they would see a death related to swine flu. Her death doesn't mean that the swine flu is any more dangerous than seasonal influenza, he said. In California this year, seven children sick with the flu have died - six of them with seasonal influenza and one with swine flu.

Karen is the third patient with swine flu to die in California since the outbreak became a public health concern in early April. The other two cases were in Southern California, and involved middle-aged patients who had pre-existing health problems.

More than 11,000 confirmed or probable cases of swine flu have been identified in the United States since April, and public health officials estimate that more than 100,000 people have been infected with it but not tested, according to the Centers for Disease Control and Prevention. Nearly two-thirds of the confirmed or probable cases have been in young people ages 5 to 24.

California has had more than 1,000 confirmed or probable cases, according to the state public health department.

E-mail the writers at eallday@sfchronicle.com and hlee@sfchronicle.com.

This article appeared on page B - 1 of the San Francisco Chronicle