Sawang Boriboon Wittaya School has closed for five days due to reported cases of dengue fever.
The school notified parents of its 4,200 students on July 14 of the closure through July 19.
Principal Arunrat Sawadchutitrakul said 10 students have contracted dengue since the school reopened July 1 and three have been sickened by Chikungunya, which also is carried by mosquitos.
During the closure the school will fumigate its buildings and grounds to destroy any mosquitos.
It also will have disinfectant sprayed to prevent diseases such as Covid-19 in response to the health panic in Rayong.