Teachers were always worried about the risk of the spread of infections in school.
In Victorian times it was very common for diseases and infections to affect almost every family in a small community, so teachers were always careful to reduce the risk of outbreaks.

This comes from the 1880 school Log Book of St Harmon's National School (church school):
"Many of the children are breaking out in sores over the face -
Spoke to Evans' mother about getting something for his face - she refused to do it so I have to make him sit separate from the others and make him wear his cap in the school on a/c [account] of his head being covered with sores".

There are lots of examples of children being banned from school if there is any risk of them bringing an illness which could spread to the other children. It was also common to close schools altogether when there was an outbreak of disease in the district...

School closed - by order...