A fever in a child

Normal body temperature varies among individuals and throughout the day. Fever is a rectal temperature of 100.4°F (38.0°C) or greater. The significance of fever is determined by clinical symptoms; some mild illnesses may cause a high fever, while some serious illnesses may cause only a slight increase in temperature.

Fever is caused by the action of exogenous (microbial, viral) pyrogens, which, by acting on tissue or blood macrophages, stimulate the release of secondary (endogenous) pyrogens. It is believed that the main endogenous pyrogens are interleukin-1 (IL-1) and tumor necrosis factor (TNF). Leukocyte interferon (a) is of lesser importance.

Fever has 3 stages: incrementi (increase), fastigii (plateau) and incrementi (decrease). Temperature decrease can be critical and lytic. With a rapid drop in high body temperature (minutes, hours) collapse is possible.

Body temperature can be subfebrile (up to 37.5 °C), febrile (high - 37.5-38.5 °C), hyperthermic (hyperpyrexia - above 38.5 °C).

Fever can be classified according to the duration and severity of individual attacks of increased temperature:

1. feverish reaction,
2. hyperthermic syndrome (Ombredanna),
3. malignant hyperthermia.

A febrile reaction involves a relatively short-term episode of increased body temperature (from several minutes to 1-2 hours) and is not accompanied by a significant deterioration in the patient's well-being. The skin is usually pink and moist. Temperature in some cases (can be high 39-40 °C), but, as a rule, is easily affected by antipyretic drugs. This reaction is called "pink" or "red" hyperthermia. Heat production predominates in its genesis.

Hyperthermic syndrome is characterized by persistent fever that is resistant to treatment with antipyretic drugs, pale skin (or paleness with acrocyanosis), deterioration of health, and sometimes impaired consciousness and behavior (lethargy, agitation).

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Causes of fever in children

Most often, acute fever in a child of the first year of life and early age is infectious in nature, mainly acute respiratory viral infections (ARVI) or gastrointestinal infections. Bacterial infections, usually otitis media, pneumonia, urinary tract infections, are less common, but can sometimes be very severe (eg, meningitis). Newborns are susceptible to infections caused by group B Streptococcus, Escherichia coli, Lysteria monocytogenes, herpes simplex virus, which are acquired perinatally.

Children under 2 years of age (especially under 3 months) are at risk for cryptogenic bacteremia, which is the presence of pathogenic bacteria in the blood of a febrile child without evidence of local damage. The most common causative organisms are Streptococcus pneumoniae and Haemophylus influenzae; vaccination against Haemophilus influenzae is now widely available in the United States and Europe, which has led to a reduction in the incidence of septicemia.

Rare non-infectious causes of acute fever include heat stroke and poisoning (eg, anticholinergics). Some vaccines (eg, pertussis vaccine ) can cause fever a day or even 1-2 weeks after vaccination, or cause vaccine-associated disease (eg, measles) after vaccination. This fever in children usually lasts from a few hours to a day. Teething does not cause fever.

Chronic fever in children may indicate various causes, from autoimmune diseases (eg, juvenile rheumatoid arthritis, non-specific inflammatory bowel disease) to cancer (eg, leukemia, lymphoma ), as well as chronic infections ( osteomyelitis, UTI).

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What to do if your child has a fever?

The workup varies by age group and focuses on identifying the source of infection or causes of noncommunicable diseases. Acute fever in a child younger than 3 months requires a thorough workup, regardless of other signs and symptoms, because severe infections (eg, sepsis, meningitis) can occur without other clinical manifestations.

Anamnesis

For children younger than 3 months, the history should focus on risk factors for sepsis, including maternal infections, prematurity, early surgery, or HIV infection. In older children, the history should focus on local symptoms and signs, immunization history, recent infections (including infections in family members and the infant's caregiver), and other risk factors for infection, including invasive medical procedures (eg, catheterization, bypass) and conditions that predispose to infection (eg, congenital heart disease, sickle cell disease, neoplasms, immunodeficiency). A family history of autoimmune diseases is also important. Although there is no direct relationship between the height of fever and the severity of the cause, temperatures greater than 103.5°F (39.0°C) place children younger than 2 years at high risk for cryptogenic bacteremia.

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Inspection

It is extremely important to assess the general condition and appearance of the child. A febrile child with signs of intoxication, especially when the temperature has already dropped, requires careful examination and further observation. In all febrile children, special attention should be paid to examining the eardrums, pharynx, chest, abdomen, lymph nodes, skin, and checking for meningeal signs. Petechiae or purpura often indicate a severe infection.

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Laboratory and instrumental examination

All febrile children should have a blood test with white blood cell count and differential, blood culture, urinalysis, and urine culture. A lumbar puncture is mandatory for children younger than 2 months; opinions vary as to whether this procedure is necessary in children aged 2 to 3 months. Chest radiography, stool white blood cell count, stool culture, and acute-phase reactants (eg, ESR, C-reactive protein, procalcitonin) are helpful.

In febrile children aged 3 to 24 months who appear well, close observation may be sufficient; laboratory testing is not necessary. If symptoms of a specific infection are present, appropriate investigations should be ordered (eg, chest radiography if hypoxemia, dyspnea, or wheezing are present; urine analysis and culture if foul-smelling urine is present). If the child has symptoms of intoxication but no focal symptoms,a complete blood count, blood culture, and urine and cerebrospinal fluid studies should be ordered.

Examination of children over 2 years of age is determined by the anamnesis and examination results; monitoring of blood culture and white blood cell count is not indicated.

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Treating fever in a child

Symptomatic treatment of fever in children usually includes acetaminophen 10 to 15 mg/kg orally or rectally every 4 or 6 hours (not to exceed 5 doses per day) or ibuprofen 5 to 10 mg/kg every 6 to 8 hours.

Treatment of infectious fever with a precisely established etiology is aimed at treating the underlying disease. Treatment of fever in a child of unknown genesis depends on the age, anamnesis and results of laboratory and instrumental examination.

Most experts recommend treating infants younger than 28 days in the hospital until laboratory results are available with broad-spectrum intravenous antibiotics. Current recommendations include ceftriaxone (50–70 mg/kg every 24 hours, or 80–100 mg/kg if high CSF counts are found) or cefotaxime (50 mg/kg every 6 hours) plus ampicillin, which is effective against listeria and enterococci. Vancomycin (15 mg/kg every 6 hours) is added if penicillin-resistant Streptococcus pneumoniae is suspected or acyclovir if herpes infection is suspected.

The decision about how much workup is needed if a child has a fever, whether to give the child antibiotics before getting culture results, whether to hospitalize the child, or whether to treat the child at home depends on the child's condition, the family's responsibility, and the presence or absence of risk factors for septicemia.