Children's fevers have many causes, not just colds. Guide for parents and signs that require medical control

A child has a fever “out of the blue” without other symptoms – cough or stuffy nose. Another who, after seeming completely recovered from a virus, has a fever again after a few weeks, repeating the same pattern. A preschooler who goes through 6-7 viruses a year, only some of which are febrile. Or the perfectly healthy child who has two sudden, intense episodes of 39-40°C that start and end suddenly. Why does fever return, how do we recognize periodic fever, fever “out of the blue” and when is medical consultation necessary? Here's a handy parenting guide for this time of year, when respiratory infections and fevers are the order of the day, but many other causes of fevers can also occur.

Fever is one of the most common reasons for presenting to the doctor, but also one of the most misunderstood reactions of the body. For parents, all of the above scenarios look the same: the child has a fever. In practice, however, the explanations can be different, and the decision to go to the doctor must take into account some clear criteria. Dr. Raluca Bidiga, pediatric specialist, emphasizes that fever is not a disease, but a symptom. The way it progresses can point to a common viral cause, a hidden infection, or even a rare autoinflammatory syndrome.

Types of fever: what is meant by acute, recurrent, prolonged, non-focal and periodic

Fever is a temporary increase in body temperature above normal values, around the range of 37.5-38 °C, being a physiological response to infection, inflammation or other medical conditions. Dr. Raluca Bidiga does not classify fever in “types”, but in ways of evolution that help to understand the clinical picture and guide investigations. The most useful definitions for parents are the following:

• Persistent fever – elevated temperature that persists for days or weeks, without returning to normal.
• Recurrent fever – reappears after a period without fever; the child has episodes separated by normal intervals.
• Periodic fever – the episodes occur at regular or almost regular intervals, and between them the child is completely healthy.
• Fever without focus – a stage term used when the cause cannot be immediately identified, not a form of fever itself.
• Acute fever – a single episode, most commonly associated with an acute viral or bacterial infection.

The doctor points out that “periodic fever”, “no focus” or “recurrent” are not diagnoses in themselves, but descriptions of the evolution, which can correspond to very different causes. Therefore, parents should not focus on the name, but on the right way of management of fever and on the criteria that require medical evaluationespecially if the fever lasts more than 3 days, occurs in a child under 6 months or is accompanied by alarm signs.

In many situations, fever is only part of the clinical picture, especially in childhood diseases, where viral and bacterial infections are common. That is why the role of the consultation is essential to avoid both over-investigation and delaying a diagnosis.

When is a fever “normal” in the cold season and when are we talking about recurrence?

For parents, the difference between successive viruses and recurrent fever is one of the most difficult interpretations. Dr. Raluca Bidiga explains that the key elements are how the episodes of the disease evolve, their regularity and the symptoms that appear with the fever. An actual infectious recurrence (eg, repeated urinary tract infections) does not look the same as typical community viruses.

Nursery and kindergarten expose children to numerous pathogens, and the rate considered normal is:

• from 1 to 3 years: up to 10-12 viral episodes/year;
• from 3 to 6 years: up to 8–10 episodes/year.

Not all of them include fever, but this frequency is not, in itself, an alarm signal. The doctor points out that only recurrent fever accompanied by persistent symptomsweight stagnation, signs of chronic infection or too short intervals between episodes may warrant further investigation.

In addition, a child diagnosed with periodic fever syndrome may, between bouts, have common colds that include fever. This overlap can create confusion, which is why the medical decision is based on careful observation of patterns: onset, duration, association with pain, cough, difficult urination, mouth breathing or ENT symptoms.

The doctor recommends consulting whenever the fever:

• occurs in children younger than 6 months;
• lasts more than 3 days;
• is associated with alarm signs (rash, breathing difficulties, dehydration, drowsiness, convulsions);
• it reappears at a constant and predictable rate.

Parents need to know that the number of febrile episodes does not establish the diagnosisbut the evolution of each episode and the child's recovery. If the child recovers quickly, eats, drinks fluids and resumes activities, further investigations are rarely necessary.

Causes of recurrent fever: infections, autoinflammatory syndromes and non-infectious diseases

According to the pediatrician, the causes of recurrent fever fall into three broad categories: infectious, genetic autoinflammatory/autoimmune and non-infectious.

1. Infectious causes

These include repeated respiratory infections, recurrent urinary tract infections, tuberculosis, Lyme disease, hidden abscesses. In these cases, the fever returns either because the infection has not been completely cleared, or because the body is frequently reinfected.

2. Autoinflammatory and genetic autoimmune syndromes

Here, episodes of fever without an infectious agent occur, caused by an abnormal activation of the immune system.

• PFAPA (Marshall) – it is about periodic fevers with aphthous stomatitis, pharyngitis and adenitis (Periodic Fevers with Aphthous stomatitis, Pharyngitis, and Adenitis). It can be triggered by stress, mild viral infections, lack of sleep, exposure to cold, or no clear factor.
• Familial Mediterranean fever (FMF) – triggered by physical/emotional stress, intense exertion, menstruation, sudden temperature changes.
• TRAPS syndrome – can be associated with stress, infections or minor trauma.

3. Non-infectious causes

These include lupus, vasculitis, drug reactions, inflammatory bowel disease, neoplasms and lymphomas.

Dr. Bidiga emphasizes that there is no “diagnostic test,” but a combination of history, clinical criteria, and targeted investigations. There are hundreds of possible tests, but their choice depends on the child's age, family history, psychosomatic development and clinical suspicion. Therefore, “by list” or “preemptive” investigation is not effective.

In addition, relapsing fever can superimpose a common virus, resulting in seemingly more frequent episodes. A detailed medical history—the “disease story,” as the doctor calls it—is often more important than laboratory data.

Fever “out of the blue”: what can it mean and how do we decide if it's an emergency?

A child who suddenly develops a fever without a cough, runny nose, or pain is usually the most cause for concern. Dr. Bidiga explains that, regardless of the cause, the first step is to control the fever and monitoring the general conditionnot searching for the diagnosis on the internet.

Correct measures at home include:

• undressing the child and maintaining a cool environment;
• cold packs or compresses;
• administration of an antipyretic suitable for age and weight (usually paracetamol);
• proper hydration;
• stopping access to the community.

The causes may vary according to age, but the doctor points out that they belong in medical treatises, not popular articles, because “in medicine we talk about diseases, not patients”, and each case can completely change the approach. The role of the parent is not to identify the disease, but to follow the signs that require consultation.

This category includes:

• the child who seems “too sick” for the fever level;
• the child is apathetic, very sleepy or difficult to wake up;
• prolonged fever over 3 days;
• the appearance of additional symptoms, such as abdominal pain, difficult urination, persistent cough, heavy breathing, frequent stools.

Once at the doctor, he decides whether additional analyzes or specialist consultations are necessary (ENT, infectious diseases, immunology, hematology). Clinical assessment remains essential and precedes investigations, as the same symptom – fever – can have completely different causes depending on the context.

Periodic fever: how do we recognize it and when we suspect an autoinflammatory syndrome?

The hallmark of periodic fever is COMPLIANCE. Parents notice that the episodes occur at fixed intervals: every 10 days, a month, two months, or some other constant interval specific to each child. Fever intensity (39-40 °C), sudden onset and full recovery between episodes are characteristic.

In PFAPA syndrome and related syndromes, fever is not accompanied by typical viral symptoms, but abdominal pain, adenopathy, or transient inflammatory signs may sometimes occur. For differentiation from repeated virosis, the doctor attaches great importance anamnesis: when the fever occurs, how long it lasts, how the child feels between episodes, if there are triggers such as stress, cold or lack of sleep.

Analyzes can guide, but do not make the diagnosis. Inflammatory tests (ESR, CRP) can be positive in periodic fever, but it depends on the time of collection and the previous treatment. A genetic test can confirm an autoinflammatory syndrome, but only in the presence of the suggestive clinical picturesays the doctor.

The differential diagnosis includes frequent viral infections, recurrent infectious fever, or fever without a focus. In practice, doctors sometimes use the “therapeutic trial”, observing how the child responds to certain interventions.

For parents, the main message is this: If the episodes are perfectly regular and the child is healthy in between, an appointment with a pediatrician or immunologist experienced in periodic fevers is recommended.

Warning signs: when do we go to the doctor or the Emergency Room?

To avoid both an unnecessary presentation to the hospital and delaying a necessary evaluation, Dr. Bidiga offers clear criteria for parents to follow:

We go to the hospital urgently if:

• the child has under 3 months and temperature above 38 °C;
• the child has between 3 and 6 months and fever above 39 °C;
• the child seems “very sick”, regardless of the measured temperature;
• appear febrile convulsions;
• fever overcomes 40 °C and does not yield to antithermics;
• there is the combination fever + difficulty breathing, dehydration, altered state, drowsiness or rashes.

We schedule a consultation with the family doctor or pediatrician if:

• the fever lasts more than 3 days;
• new symptoms appear: cough, earache, abdominal pain, difficult urination, frequent stools, oral breathing;
• fever returns at regular intervals or too often;
• the child does not recover between episodes.

When it comes to managing fever at home, the most common mistakes are:

• excessive administration of drugs at low temperatures (37.2-37.3 °C);
• chaotic alternation of antipyretics for long periods;
• avoiding any treatment for fevers of 39-40 °C in the idea that “the body must fight by itself”;
• lack of adequate hydration.

The correct recommended routine is as follows: monitoring, comfortable environment 22-24 °C, light clothes, hydration, antipyretic only if the fever exceeds 38-38.3 °C or if the child is uncomfortable. If the fever persists or alarm signs appear, medical consultation is mandatory.