Health officials are still investigating the cause of an outbreak of symptoms that led to the closure of an elementary school in Buford on Friday.

East Metro Health District officials recommended that Harmony Elementary School be closed on Friday after 24 percent of students, 131 total, were absent on Thursday. The school reopened on Monday as planned.

“The East Metro Health District recommended the closure as a large number of students have recently shown symptoms of gatroenteritis, sometimes referred to as the ‘stomach flu,’” school administrators said in a letter to parents.

“Gastroenteritis often causes diarrhea and/or vomiting.”

The virus can be spread through close contact with an infected individual or by eating or drinking contaminated foods, health officials say.

“When the health department recommended that we close on Friday, they told us that school could reopen on Monday,” said Jorge Quintana, Gwinnett County Schools spokesperson.

On Monday, absences dropped to around 6 percent, or 42 students, Quintana said.

“Recommendations to close the school were made after working closely with the school district and looking at the high number of absenteeism as well as the number of ill students,” said Suleima Salgado, East Metro Health District public information officer.

“Typically persons recover within one to three days, therefore we worked with the school to clean the school on Friday and into the weekend. Ill students were requested to stay home until symptom-free; other students were welcome to return to school on Monday.”

According to system officials, all “horizontal surfaces” in the school had to be sanitized before students returned.

Although the stomach flu is the expected cause of illness in the school, the health district’s completed investigation will pinpoint the specific illness, as well as naming a source.

Currently, health officials do not believe the widespread illnesses were related to the H1N1 virus.