From the Guidelines
Fever is a common symptom in infants, and the incidence of fever in a 5-month-old infant is not explicitly stated in the provided studies, but it can be inferred that fevers are frequent in this age group due to their immature immune system and exposure to new pathogens 1.
Definition of Fever
A fever in a 5-month-old is typically defined as a rectal temperature of 100.4°F (38°C) or higher, which is a common definition used in clinical settings 1.
Causes of Fever
These fevers are often caused by viral infections as babies encounter new germs while their immune systems are still developing, and the risk of serious bacterial infections (SBIs) is a concern in this age group 1.
Management of Fever
For a 5-month-old with a fever, infant acetaminophen (Tylenol) can be given at a dose of 10-15 mg per kg of body weight every 4-6 hours as needed, but it is essential to consult a doctor before administering any medication, especially if the fever is 102°F (38.9°C) or higher, lasts more than 2-3 days, or is accompanied by other concerning symptoms like unusual fussiness, lethargy, poor feeding, rash, or difficulty breathing 1.
Key Considerations
It is crucial to keep the baby comfortable by dressing them in light clothing, maintaining a comfortable room temperature, and ensuring they stay hydrated with breast milk or formula, and to seek medical attention promptly if there are any concerns about the infant's health 1.
Risk of Serious Bacterial Infections
The risk of SBI in febrile infants and children has been reported to be around 7% in infants aged 90 days or younger, and it is essential to consider this risk when evaluating a febrile infant 1.
Clinical Predictors
Clinical predictors, such as age, temperature, and laboratory test results, can help identify patients at risk for SBIs, and evidence-based recommendations can guide the management of well-appearing febrile infants and children 1.
From the Research
Incidence of Fever in Infants
- The incidence of fever in infants, particularly those around 5 months old, is a common concern in pediatric care 2, 3, 4.
- According to the study by 4, about 20% of fevers in childhood have no apparent cause, and a small but significant number of these children may have a serious bacterial infection.
- The study by 2 mentions that urinary tract infections cause more than 90% of serious bacterial illness in children, and younger children have a higher incidence of infection.
- Another study by 5 states that unexplained fever is the most common symptom of urinary tract infection during the first two years of life.
Age-Specific Considerations
- For infants under 28 days, hospitalization is recommended, with cultures of blood, urine, and spinal fluid taken and empirical antibiotic therapy administered immediately 4.
- For febrile infants 28 to 90 days of age, evaluation is needed to determine whether they are in the low-risk group for serious bacterial infections, using criteria such as the Rochester Criteria 4.
- For children 3-36 months old, the Yale Observation Scale is recommended to assess febrile children and the risk of occult bacteremia 4.
Diagnostic Approaches
- A urinalysis and urine culture should be performed when urinary tract infection is suspected 5.
- Blood work, including white blood cell count, absolute neutrophil count, and C-reactive protein, may be used as predictors of serious bacterial infection in febrile children, but their interpretation should consider the duration of fever 6.
- Imaging studies should be used judiciously to minimize exposure to radiation in children with suspected urinary tract infections 5.