North Kingstown High School sophomore Lauren Poirier, 16, greets her grandmother, who arrived to pick her up after school on Wednesday. The school has been closed for the rest of the week.

The Providence Journal / Bob Breidenbach

North Kingstown High School has shut down for this week because a student may have contracted swine flu.

The girl fell ill after traveling to Mexico for spring break. Test results are expected Friday or Saturday. Meanwhile, all extracurricular activities and home and away sports for the high school have been canceled. SAT testing scheduled for Saturday at the high school will be postponed to May 16. Other schools will remain open.

The student, who is not being identified, was not seriously ill and had already returned to school. No one among her family, friends or classmates has fallen ill.

The state Health Department is calling the student’s illness a “probable case” of swine flu. If swine flu is confirmed, the school will be closed for seven days to reduce the likelihood that the disease will spread.

“We are taking this step out of an abundance of caution,” Governor Carcieri said at a State House news conference announcing the school closure. “This is a very rapidly emerging situation. …We have to be prepared and be concerned because there are a lot of unknowns.”

The North Kingstown closure came on a day of many developments in the swine-flu outbreak. A toddler in Texas became the first swine-flu fatality on American soil; swine-flu cases were identified in additional states, including Massachusetts and Maine; and the World Health Organization raised the flu-alert level to five, indicating a pandemic is imminent.

In Rhode Island, said Health Director David R. Gifford, “We’re not seeing any huge outbreak. What’s concerning us is the numbers we’re seeing in other parts of the country. … It is just a matter of time before we get a confirmed case in Rhode Island.”

The North Kingstown student visited a doctor sometime after returning from a family trip to Mexico on April 17. Last weekend, the doctor received a swine-flu alert and told the Health Department about the student.

Additional testing in the Health Department laboratory could not identify the strain of influenza that the student has, raising the possibility that it is swine flu. Of about a dozen tested in Rhode Island, this is the only sample so far sent to the U.S. Centers for Disease Control and Prevention in Atlanta, the only place in the United States able to identify swine flu.

Gifford said that it typically takes 24 to 48 hours for the CDC to complete the test, but noted that the laboratory is currently overwhelmed with samples.

The Health Department learned that the student’s sample was suspect late Tuesday night, and notified North Kingstown Supt. Philip D. Thornton. Thornton said the decision to close the school was made in consultation with the Health Department at 11 a.m. Wednesday, effective at the end of the school day, 2 p.m. Parents were notified via e-mail and phone.

Thornton noted that the hand-gel dispensers in schools have all been filled with sanitizer.

If the test is positive for swine flu, there will be no reason to clean the school, because the virus does not last long on surfaces, Gifford said. Instead, the school will be closed for seven days. Closing schools is a time-tested way to slow or stop the spread of disease, by dispersing people who otherwise would be in close quarters.

An infected person can be contagious before having symptoms. The time from infection to symptoms can range from one to seven days. So if someone were infected by the student in recent days, that person might not know it till next week, and meanwhile could infect more people.

The student apparently still had symptoms after returning to school. Gifford emphasized the importance of staying home when one is sick. He advised sick people to seek medical care only if they feel badly enough that they normally would see a doctor.

Elliot Krieger, spokesman for the state Department of Education, said that no decision has been made on whether North Kingstown will have to make up the missed days at the end of the year.

Health officials have asked school departments around the state to report any unusual absenteeism, especially if people have flu-like symptoms. So far, no school is seeing any unusual patterns, Gifford said.

Carcieri, who has taken a tough stand against illegal immigration, was asked about online comments blaming the swine-flu cases on immigrants. The governor rebutted those statements: “This is the swine flu. People who contracted it are Americans who traveled to Mexico. This is not an immigration issue.”

ffreyer@projo.com