The head of a hospital in the remote highland town of Wabag told The Post-Courier that so far the source of the outbreak had not been determined, although poor school facilities have been blamed.
The disease had been confirmed through blood tests, chief executive Salan Ere said.
"At this point in time we should not blame the cause of the disease as poor school facilities," he was quoted as saying.
Students had reportedly blamed poor hygiene in the kitchens and dormitories. Two secondary schools are affected.