The child, who is not being identified, attends Helmsdale Primary School.
The Health Protection Team at NHS Highland is working with Highland Council education service following the confirmation of a case of Tuberculosis (TB).
A statement from NHS Highland said: “The affected child did not catch the infection at school and remains well.”
A letter and leaflet providing further information has been given to all parents and staff.
The statement added: “NHS Highland are continuing to investigate this case and their contacts and will provide further written information and advice to parents and staff shortly after school reopens following the midterm break holiday on Monday.
“This brings the total number of cases of TB being investigated and treated in the Helmsdale area to three.
“For TB to spread it requires the affected person to be infectious and also to have had prolonged, close contact with others, such contact is usually only found in the home.
“It is very unlikely there has been any spread of infection from a child in the school setting.”
Dr Ken Oates, Consultant in Public Health Medicine at NHS Highland, said: “We realise some parents will be anxious about this but would seek to reassure everyone that the risks to other pupils and staff are minimal.
“We will write again to parents as soon as the midterm break is over. In the very unlikely event that another child is found to have the TB infection effective antibiotic treatment is available.
“I would like to thank the head teacher Linda Gill for her full cooperation and the help she has given us in dealing with this matter.”
Tuberculosis is a bacterial disease caused by the bacteria Mycobacterium TB.
It usually presents with respiratory symptoms such as a prolonged cough, often accompanied by sweats and weight loss. It usually responds well to antibiotic treatment.
In the last five years NHS Highland has had an average of 13 cases of confirmed pulmonary TB cases each year.