Rhode Island Health Director David R. Gifford, left, and Governor Carcieri answer questions at a State House news conference Wednesday on the swine-flu death of Victoria Sousa. The Providence Journal / Ruben W. Perez

The 12-year-old Bristol girl who died Monday had been infected with swine flu, test results confirmed Wednesday.

The girl, Victoria Sousa, is the fourth Rhode Islander to die of swine flu since it arrived in the state last spring, the first who was apparently healthy when infected and the first to die since the virus resurged this fall.

Swine flu, or H1N1, is spreading quickly around Rhode Island, with 88 schools reporting unusually high absenteeism on Wednesday and pediatricians’ offices besieged with calls. Swine flu is typically a mild illness but can be fatal in rare cases. About 100 children around the country have died from it since the spring.

Victoria, a seventh-grader at St. Philomena’s School in Portsmouth, came down with mild flu symptoms last week and stayed home from school on Friday. On Monday, she took a sudden turn for the worse and died that day. Her death comes days before the Health Department starts swine-flu vaccination clinics in all 435 schools in the state.

“Our thoughts, prayers and hearts go out to the family,” Governor Carcieri said at a State House news conference announcing the H1N1 test results.

Governor Carcieri called on parents to be vigilant if their children get the flu, start to get better and then get worse. This pattern indicates that the child may have picked up a bacterial infection. He said he had seen this pattern in his own grandchildren and their friends, although everyone recovered.

It is not clear, however, whether Victoria’s illness followed this course.

Frank McMahon, a friend of the Sousa family who acted as spokesman, said that Victoria’s parents, Louis and Catherine Sousa, of Bristol, did not want to provide details of her illness. He did say that on Sunday she seemed to be improving to the point that there was talk of her returning to school the following day. But on Monday, she suddenly grew worse.

Word of her death spread so quickly that classmates gathered at 6 p.m. Monday at St. Philomena’s to meet with nuns and try to come to grips with the tragedy.

Health Director David R. Gifford called the family personally to report the test results, less than an hour before the 4 p.m. news briefing Wednesday, Mahon said.

“The thing that’s frightening is that we don’t know why and how” the swine flu contributed to her death, McMahon said.

Gifford said that autopsy results, expected in a couple of weeks, should reveal how the H1N1 virus led to Victoria’s death.

When the flu kills, death usually results from one of three causes, Gifford said: the influenza virus itself causes pneumonia, or lung inflammation; the flu makes the person vulnerable to bacteria that cause pneumonia; or the flu exacerbates an underlying condition.

Influenza can wipe out the lungs’ normal defenses against infection, making a previously healthy person vulnerable to bacteria.

The state plans to produce public-service announcements on how to tell when the flu becomes serious, Carcieri said. “We need everyone to be a little extra vigilant,” he said. “It’s obviously here, and it’s obviously spreading.”

Most children can recover from the flu by resting at home, taking fever-reducing medication and drinking fluids. But if a child has fast breathing, difficulty breathing or blueness around the lips; isn’t urinating or eating; is severely lethargic or irritable; or just seems very sick, parents should call their pediatrician.

Gifford said that no changes will be made in the order of school-based flu clinics, which start Monday and run for 28 days. Victoria’s school, St. Philomena’s, is scheduled for day 13, likely to fall in the third week. Gifford said St. Philomena’s will not move to the front of the line because many schools have a large number of flu cases. “We don’t have enough vaccine for all the schools that have a current outbreak,” he said.

The state had hoped to conduct the clinics –– which are free and voluntary –– over two or three weeks in October, but manufacturing problems have delayed supplies of vaccine. The state learns week by week how much will be available.

“We absolutely know we have enough vaccine for the clinics next week,” Gifford said.

Victoria Sousa was a gifted athlete who began playing soccer when she was 5 years old in the Bristol Youth Soccer Association and belonged to championship teams in 2008 and 2009. She was selected in 2009 for the Rhode Island Olympic Developmental Soccer Program.

“She floated when she ran. She was beautiful to watch,” said her uncle, David Sousa.

Victoria, who loved the Independence Day holiday, was chosen “Little Miss Fourth of July” for Bristol’s 2006 celebration. McMahon, the family spokesman, remembered her as a “vibrant and happy young lady.”

The family is devastated by Victoria’s death but at the same time greatly comforted by an outpouring of support from families at St. Philomena’s School and St. Mary’s Academy-Bay View, where her sisters, Marguerite and Emily, are students, McMahon said.

gmacris@projo.com