A child with a fever of 39 degrees can have both viral and bacterial infections and needs to be seen by a doctor for further examination. It is not possible to determine whether a fever of 39 degrees is caused by a viral infection or a bacterial infection based on the symptoms alone. Both viral and bacterial infections can cause fever in children. Generally speaking, bacterial infections, such as acute suppurative tonsillitis and Streptococcus pneumoniae, may lead to a fever of 39 degrees, while viral infections, such as adenovirus pneumonia and measles, may also cause a fever of 39 degrees. Therefore, it is necessary to carry out a comprehensive examination and assessment of the child to determine whether it is a viral or bacterial infection. If your child has a fever of 39 degrees, it is recommended that you seek prompt medical attention, complete the examination, identify the cause of the illness, and then give targeted treatment to avoid delaying the condition.