Fever is one of the warning signs and symptoms of disease in the body. In fact, fever indicates the fight and response of the body's immune system to fight pathogens. Fever in children is also very common due to weak immune system. The presence of infection in the body or cold viruses is one of the most important causes of fever in babies and children, which is often accompanied by other symptoms. But sometimes the child has a fever without any specific symptoms. But what is the symptom of fever without cause and infection in children? Stay with us until the end of this article on Dr. Ali Faraji's website and get to know the most common causes of fever without origin and ways to treat it. What is a fever without any other symptoms in children? Fever with no known cause and no other symptoms of the disease is used to describe acute cases (lasting less than a week). It is very important to pay attention to fever, especially in children under 36 months, because in most cases they are caused by severe and local infections in the body of the child or infant. It is usually difficult and important to distinguish between dangerous bacterial infections and self-limiting viral infections. Most children who develop self-limiting viral infections recover without complications. But fevers caused by hidden bacteria and diseases such as meningitis do not improve without treatment and may be dangerous if not diagnosed in time. Causes of fever without cold symptoms in children Fever without cold symptoms in children can occur for several reasons. If your child has a fever without cold symptoms, it is important to see a doctor as soon as possible to diagnose the cause of the fever and start the treatment process. The most common causes of fever without cold symptoms in a child are: ### 1- Viral infections Some viruses can cause fever in children without cold symptoms. These infections may not have other symptoms such as coughing, sneezing, sore throat or nausea. ### 2- Bacterial infections Some bacterial infections can also cause fever without cold symptoms in children. Examples of these infections include ear infections, pharyngitis, urinary tract infections, and upper respiratory tract infections. ### 3- Complications after vaccination After vaccination, some children may have a fever without cold symptoms. These vaccines can stimulate the immune system and cause fever. **✍️ Know more: Types of vaccines that should be injected to children** ### 4- Inflammatory diseases Some inflammatory diseases such as rheumatoid arthritis, Crohn's disease, inflammatory colitis and lupus can cause fever without cold symptoms in children. ### 5- Side effects of drugs Taking some medicines may cause fever without cold symptoms in children. Some non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics may have these side effects. ### 6- Other environmental reasons Other reasons such as increased physical activity, changes in environmental conditions (such as heat or climate change), anxiety or stress may also cause fever without cold symptoms in children. **Factors affecting unexplained fever in children** Diagnosing fever, its pathogens and risk factors is difficult for different ages, especially in children from 1 to 36 months. Fever in babies less than one month is characterized by higher than 38 degrees Celsius. In this age group, dangerous bacterial infections that cause fever without local symptoms, and most of its pathogens appear in the late part of childbirth. In infants aged 1 to 3 months, Streptococcus pneumoniae is one of the possible causes of fever without origin, and the prevalence of obstetric pathogens will be lower. Also, the presence of hidden bacteria, kidney infections, urinary infections and meningitis are other effective factors in unexplained fever in infants and children under three years of age. Common causes of latent fever in children Although various factors such as cold viruses and bacteria are the most common causes of fever, other factors can also cause fever with or without specific symptoms. The most common causes of fever in children 3 to 36 months old are the following infections and bacteria: - Streptococcus pneumoniae (the cause of pneumonia) - Streptococcus group B (causing GBS infection) - Neisseria meningitidis (bacteria causing meningitis) - Haemophilus influenzae type B (the cause of bacteremic infections such as blood infection, meningitis) - Staphylococcus aureus (causing skin infections and infections causing meningitis, pneumonia, etc.) It should be noted that vaccination of children greatly reduces the incidence of dangerous infections such as streptococcus pneumoniae and group B streptococcus. Diseases that cause unexplained fever in infants and children As mentioned above, bacteria such as Streptococcus pneumoniae, Streptococcus group B, Haemophilus influenzae type B, Neisseria meningitidis and Staphylococcus aureus are the main causes of latent fevers in children. Each of these viruses is effective in causing infectious diseases. The main diseases that cause frequent fever in children are: - Meningitis - Pneumonia (lateral chest) - Urinary tract infection - Infectious arthritis (viral or bacterial infection in the joints of infants) - Emphalitis (inflammation and infection of the soft tissue around the navel) - Otitis media (ear infection) - Gastroenteritis (inflammation of the intestines and stomach) - Osteomyelitis (bone inflammation, bone marrow inflammation or bone infection) - Skin infections **Symptoms and symptoms of unexplained fever in children** As mentioned above, fever without a cause refers to a fever that occurs without signs or symptoms of the disease in the child's body. In fact, the baby or child does not have any specific symptoms other than fever in his body. But in some cases, the presence of some small symptoms along with fever can be a sign of one of the infectious diseases. Most bacteremic diseases and hidden infections may present with other symptoms in addition to fever, which include: - Lethargy and reduced activity - Crying with high intensity - Child restlessness - Sleep disorder - Paleness - Reduce eye contact - Vomiting and diarrhea - Abnormal vital signs - Weight loss - Difficult and inappropriate nutrition - Increased respiratory activity or the movement of the nasal lobes with intercostal depression and moaning **Determining the cause of hidden fever in children** In most cases, the cause of fever in children can be diagnosed with detailed history and physical examination including contact with patients and history of vaccination along with repeated clinical examinations. In infants, a complete evaluation for sepsis is necessary, including CBC, blood culture, U/A, and U/C obtained by bladder cannulation. Also, LP with gram-stained CSF culture is also performed for infants and children with unexplained fever. In addition to the mentioned cases, it is necessary to perform CXR, stool culture and stool guaiac test based on clinical symptoms and history. In infants who appear well and have normal blood tests, U/A and CSF analysis, the risk of dangerous bacterial infection will be lower. In infants aged 3 to 36 months, the risk of serious bacterial infections increases if the fever is higher than 39°C. U/A will be necessary in girls, uncircumcised boys until the age of 12 months and circumcised boys until the age of 6 months. Blood culture and LP are necessary if necessary based on the presentation and history of the disease. In infants who receive three doses of Voxastrep pneumonia (prevnar) and Haemophilus influenzae (HiB), the risk of disease is much lower. Treatment of unexplained fever in children Empirical antibiotic therapy is started immediately for toxic patients (disease caused by bacterial toxins) or sick appearance. Infants under one month should be hospitalized and treated empirically after evaluation is completed. Most infants should be treated with ampicillin plus a third-generation cephalosporin or gentamicin. If the blood tests, U/A and CSF examination are normal, the status of infants aged 1 to 3 months should be followed up within 24 hours by the staff of medical and health centers. In non-toxic children older than one month, daily follow-up of the clinical condition is sufficient until the culture results are ready or new symptoms appear. Children with urinary tract infection, if unable to consume fluids and oral antibiotics, or if they are not sure of follow-up, or if they are unwell, they need to be seen by a pediatrician and be monitored in the hospital if needed. ### **And but in the end...** Unexplained fever in children, especially in infants and children under three years of age, is a sign of hidden infection or bacteria. Diseases such as meningitis, pneumonia, infectious arthritis, office infections, etc., are among the most important causes of fever without specific symptoms and signs. Timely diagnosis and treatment of these diseases is very important. On the other hand, it is vital to follow up and evaluate the condition of the baby or child from moment to moment, therefore, in some cases, hospitalization of children in the hospital is recommended by the doctor. **\*~