One and a half year old baby fever to 39.5 ℃ can be seen in toddler rash, intracranial infection or Kawasaki disease and other conditions, whether it is serious need to combine with the baby’s condition to determine, such as the baby’s mental response is poor, convulsions, etc., consider intracranial infection, usually more serious, need to be actively treated. 1.toddler rash: is a common disease in infants and young children, is caused by human herpes virus infection, clinical temperature of 39.5 ℃, the course of the disease is often a good mental response, usually fever 3 ~ 5 days fever out of the rash, this kind of disease in the course of the disease for a reasonable fever, often a good prognosis, the general condition is not serious, but the course of the disease still need to be closely observed the change of the condition, etc.. 2. Intracranial infections: such as viral encephalitis, clinical high fever, such as body temperature of 39.5 ℃, may be accompanied by convulsions, projectile vomiting, poor mental response and other phenomena, perfect lumbar puncture can assist in the diagnosis of such diseases are usually more serious, and need to be actively consulted for treatment. 3. Kawasaki disease: also known as cutaneous mucocutaneous lymph node syndrome, clinical recurrence of fever, can be accompanied by chapped lips, hands and feet, etc., need to actively consult the doctor for treatment, such as treatment is not timely can appear coronary artery dilation or even aneurysm and other serious complications. 4. Other: such as acute leukemia, can also appear the above phenomenon, often fever, can be accompanied by mucosal bleeding and other phenomena, bone marrow aspiration and other tests can assist in the diagnosis, usually more serious, and need to be actively treated. When the baby’s fever reaches 39.5, it is recommended to consult a specialist for a comprehensive assessment to determine whether the fever is serious.