What are the common causes of a persistent low grade fever. How long can a low grade fever last before it becomes concerning. What symptoms accompany a persistent low grade fever. When should you see a doctor for a prolonged low grade fever.

Understanding Low Grade Fever: Definition and Significance

A low grade fever is characterized by a slight elevation in body temperature, typically ranging between 100.5°F (38°C) and 102.2°F (39°C). While the average human body temperature is around 98.6°F (37°C), it’s important to note that this can fluctuate throughout the day. When a low grade fever persists for more than two weeks, it’s considered a persistent low grade fever.

Why does the body raise its temperature? Fever is often a natural defense mechanism, with the body increasing its core temperature to combat infections or other health issues. However, prolonged low grade fevers can sometimes indicate underlying conditions that require medical attention.

Recognizing the Symptoms of a Persistent Low Grade Fever

While some individuals may barely notice a low grade fever, others might experience a range of symptoms. These can include:

• Feeling warm to the touch
• Sweating or chills
• Shivering
• Headaches
• Muscle aches
• Dehydration
• General malaise or feeling unwell

Is it possible to have a fever without feeling sick? Yes, some people may have an elevated body temperature without experiencing other noticeable symptoms. However, the presence of additional symptoms can provide valuable clues about the underlying cause of the fever.

Common Causes of Persistent Low Grade Fever

Respiratory Infections

Respiratory infections are among the most frequent causes of persistent low grade fevers. These can include:

• Common cold
• Influenza (flu)
• Bronchitis
• Pneumonia

How long can a fever from a respiratory infection last? In many cases, the fever may persist for as long as it takes the body to fight off the infection, which can be several days to a week or more. Additional symptoms of respiratory infections often include coughing, sneezing, nasal congestion, sore throat, fatigue, and loss of appetite.

Urinary Tract Infections (UTIs)

UTIs occur when bacteria multiply in any part of the urinary system, including the bladder, urethra, kidneys, or ureters. Besides a low grade fever, symptoms of a UTI may include:

• Abdominal pain
• Burning sensation during urination
• Frequent urination
• Persistent urge to urinate
• Dark or cloudy urine

Can a UTI cause a fever without other symptoms? While it’s possible, it’s more common for a UTI to present with multiple symptoms. If you suspect a UTI, it’s important to consult a healthcare provider, as most cases require antibiotic treatment.

Less Common Causes of Persistent Low Grade Fever

Other Infections

Various other infections can lead to a persistent low grade fever, including:

• Food poisoning
• Tuberculosis
• Meningitis
• Infections from exposure to livestock pathogens

These infections often come with their own set of specific symptoms. For instance, food poisoning may cause nausea, vomiting, and diarrhea, while meningitis might lead to severe headaches and neck stiffness.

Medication Side Effects

Some medications can cause low grade fevers as a side effect. How quickly does a medication-induced fever resolve? According to a 2018 review, if a medication is the cause of the fever, it typically subsides within 72 hours of discontinuing the drug. However, it’s crucial to consult with a healthcare provider before stopping any prescribed medication.

Chronic Stress

Interestingly, chronic stress can manifest physically as a low grade fever. A 2015 research paper noted that stress-induced fevers are most common in young women. In these cases, addressing the underlying stress may help resolve the fever.

When Persistent Low Grade Fever Might Indicate Something Serious

Cancer and Persistent Fever

In rare cases, a persistent low grade fever with no apparent cause could be a sign of certain cancers, such as:

• Leukemia
• Hodgkin lymphoma
• Non-Hodgkin lymphoma

What other symptoms might accompany a cancer-related fever? Additional symptoms can include persistent fatigue, weakness, unexplained weight loss, enlarged lymph nodes, and night sweats. However, it’s important to note that these symptoms are not unique to cancer and can be associated with many other conditions.

Diagnosing the Cause of a Persistent Low Grade Fever

Determining the underlying cause of a persistent low grade fever often involves a comprehensive approach:

1. Medical history review: Your doctor will ask about your symptoms, recent travel, medications, and any potential exposures to infections.
2. Physical examination: This can help identify signs of infection or other health issues.
3. Laboratory tests: Blood tests, urine analysis, and cultures may be ordered to check for infections or other abnormalities.
4. Imaging studies: X-rays, CT scans, or MRIs might be necessary to investigate potential sources of infection or other underlying conditions.

How long does it typically take to diagnose the cause of a persistent fever? The time frame can vary significantly depending on the complexity of the case and the tests required. Some causes may be identified quickly, while others might require more extensive investigation.

Treatment Approaches for Persistent Low Grade Fever

The treatment for a persistent low grade fever depends on its underlying cause:

• Infections: Bacterial infections often require antibiotic treatment, while viral infections may need supportive care to manage symptoms.
• Medication-induced fevers: Discontinuing or changing the offending medication under medical supervision may resolve the issue.
• Stress-related fevers: Stress management techniques, therapy, or lifestyle changes may be recommended.
• Underlying medical conditions: Treatment will focus on addressing the specific condition causing the fever.

In addition to treating the underlying cause, managing the symptoms of a low grade fever may involve:

• Staying hydrated
• Getting plenty of rest
• Using over-the-counter fever reducers like acetaminophen or ibuprofen, as recommended by a healthcare provider

Is it always necessary to treat a low grade fever? Not necessarily. In many cases, a low grade fever is a sign that your body is effectively fighting an infection. However, if the fever persists or is accompanied by concerning symptoms, it’s important to seek medical advice.

When to Seek Medical Attention for a Persistent Low Grade Fever

While many causes of persistent low grade fever are not immediately life-threatening, there are situations where medical attention is warranted:

• The fever persists for more than two weeks without an obvious cause
• The fever is accompanied by severe symptoms such as difficulty breathing, chest pain, or severe headache
• You have a weakened immune system due to conditions like HIV/AIDS or cancer treatment
• You’ve recently traveled to an area with high rates of infectious diseases
• You’re experiencing unexplained weight loss, night sweats, or other concerning symptoms

How quickly should you seek medical attention for a persistent fever? If you’re experiencing any of the above situations, it’s advisable to consult with a healthcare provider as soon as possible. They can assess your condition and determine if further investigation or immediate treatment is necessary.

Preventing and Managing Persistent Low Grade Fevers

While not all causes of persistent low grade fever are preventable, there are steps you can take to reduce your risk and manage your overall health:

• Practice good hygiene, including regular handwashing, to prevent infections
• Stay up to date on vaccinations
• Maintain a healthy lifestyle with a balanced diet, regular exercise, and adequate sleep
• Manage stress through relaxation techniques, mindfulness, or seeking support when needed
• Follow medication instructions carefully and report any side effects to your healthcare provider
• Attend regular check-ups and screenings as recommended by your doctor

Can lifestyle changes help prevent recurrent low grade fevers? While they may not prevent all cases, maintaining good overall health can strengthen your immune system and potentially reduce the frequency and duration of fevers.

Understanding persistent low grade fevers and their potential causes is crucial for maintaining optimal health. While many cases resolve on their own or with simple treatments, being aware of the signs that warrant medical attention can ensure timely intervention when necessary. By staying informed and proactive about your health, you can better navigate the complexities of persistent low grade fevers and work towards a swift recovery.

Persistent low grade fever: Causes and treatments

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Medical News Today only shows you brands and products that we stand behind.

Our team thoroughly researches and evaluates the recommendations we make on our site. To establish that the product manufacturers addressed safety and efficacy standards, we:

• Evaluate ingredients and composition: Do they have the potential to cause harm?
• Fact-check all health claims: Do they align with the current body of scientific evidence?
• Assess the brand: Does it operate with integrity and adhere to industry best practices?

We do the research so you can find trusted products for your health and wellness.

Read more about our vetting process.

Was this helpful?

The normal human body temperature is about 98.6°F, but it fluctuates throughout the day. A low grade fever is when the body temperature rises slightly, usually between about 100.5°F and 102.2°F.

The fever is persistent when the body temperature stays in this range for more than 2 weeks.

A fever is commonly a result of the body trying to fight off an infection or another illness. However, some cases are more difficult to diagnose and treat.

Continue reading to learn more about the symptoms, causes, and treatment of a persistent low grade fever.

Share on PinterestIf the body is fighting off an infection, a person may experience a persistent low grade fever.

Some people may hardly notice that they have a low grade fever. However, others may experience various symptoms, including:

• feeling warm to the touch
• sweating
• chills
• shivering
• headaches
• muscle aches
• dehydration
• a general feeling of being unwell

A persistent low grade fever is typically a sign that the body is fighting off an infection or another health issue and has raised its temperature to help these efforts.

These underlying issues can include:

Respiratory infections

Respiratory infections can cause a persistent low grade fever. Some of the most common respiratory infections, such as a cold or the flu, may cause a low grade fever that lasts for as long as the body takes to fight off the infection.

Other symptoms that may indicate a respiratory infection include:

• coughing
• sneezing
• a stuffy or runny nose
• a sore throat
• chills
• general fatigue
• lack of appetite

Many simple respiratory infections do not require treatment, and the symptoms will go away in time.

Urinary tract infections

A urinary tract infection (UTI) may also be the underlying cause of a low grade fever. A UTI is a bacterial infection that occurs when bacteria multiply anywhere in the urinary tract, which includes the bladder, urethra, kidneys, and ureters.

In addition to a low grade fever, the person may experience symptoms such as:

• pain in the abdomen
• a burning sensation while peeing
• frequent urination
• a constant urge to urinate
• dark urine

Most UTIs are simple to treat with antibiotics. The doctor may analyze a urine sample to determine the precise type of bacteria causing the infection to ensure that they prescribe the right treatment.

Other infections

Share on PinterestA person should talk to their doctor if they experience any symptoms of infection alongside a fever.

Almost any infection can cause a fever. A fever is one of the body’s natural responses to foreign invaders. The body may keep its core temperature elevated while it is fighting off the infection.

Other sources of infections that may cause a low grade fever include:

• food poisoning
• exposure to pathogens from livestock
• tuberculosis
• meningitis

Anyone experiencing symptoms of infection alongside a fever should see a doctor if the symptoms do not improve with rest and time.

Medications

Some medications can cause many different side effects, which may include a low grade fever. People can check the information on side effects and interactions that comes in the packaging or seek advice from a pharmacist.

As the author of a 2018 review notes, if the medication is the cause, the fever should go away very quickly — typically within 72 hours — once the person stops taking the drug.

Stress

Chronic stress may cause a low grade fever. A research paper from 2015 notes that a fever due to stress is most common in young women.

Reducing stress levels may resolve the fever in these cases.

Cancer

In rare cases, a persistent low grade fever with no known cause may be a sign of cancer.

A persistent fever can be a symptom of leukemia, Hodgkin disease, or non-Hodgkin lymphoma.

The person may also experience other symptoms of cancer, including:

• persistent fatigue
• weakness
• headaches
• infections
• lack of appetite
• excessive bruising or bleeding
• unexplained weight loss
• enlarged lymph nodes
• excessive sweating at night

Many of these symptoms are not unique to cancer, however.

Anyone who experiences these symptoms along with a low grade fever should see a doctor for a diagnosis.

Chronic disorders

Many other chronic disorders may cause symptoms such as a low grade fever, including:

• thromboembolic disease
• arthritis
• lupus
• gout
• thyroiditis
• serum sickness-like reactions
• serotonin syndrome
• neuroleptic malignant syndrome

Diagnosing a persistent low grade fever may involve several different tests to eliminate potential causes.

The doctor will generally carry out a physical examination and question the person regarding additional symptoms and whether they have any chronic conditions.

The doctor may also ask about any medications that the person takes so that they can eliminate them as a cause of the fever.

They may order blood tests, such as a complete blood count (CBC), to get an overview of the person’s health. The results may help them decide which other tests, if any, they need to order.

If the doctor suspects that the person has a UTI, they may ask them for a sample of their urine to test.

Share on PinterestOTC drugs may help treat a low grade fever at home.

Treatment for a persistent low grade fever will depend on the cause. For instance, minor infections may not need treatment at all, whereas issues such as cancer require extensive treatment.

To alleviate the symptoms of a low grade fever at home, a person can try over-the-counter (OTC) drugs, such as ibuprofen (Advil) or acetaminophen (Tylenol).

A fever can cause dehydration, so it is vital to drink plenty of water.

It is important to treat a low grade fever in children, who may be more sensitive to temperature changes. Using children’s versions of OTC drugs may help control the fever while waiting to see a doctor.

A persistent low grade fever is a sign of an underlying issue, such as a mild infection or chronic condition. The fever may persist while the person is fighting off the infection.

For the most part, persistent low grade fevers are not a cause for concern. However, it is important to monitor the fever to see whether it gets worse.

Anyone who is concerned about their symptoms or experiences a persistent low grade fever for more than 10 days should see a doctor.

SHOP FOR OTC DRUGS

The drugs listed in this article are available online:

• Ibuprofen
• Acetaminophen

Persistent low grade fever: Causes and treatments

We include products we think are useful for our readers. If you buy through links on this page, we may earn a small commission Here’s our process.

Medical News Today only shows you brands and products that we stand behind.

Our team thoroughly researches and evaluates the recommendations we make on our site. To establish that the product manufacturers addressed safety and efficacy standards, we:

• Evaluate ingredients and composition: Do they have the potential to cause harm?
• Fact-check all health claims: Do they align with the current body of scientific evidence?
• Assess the brand: Does it operate with integrity and adhere to industry best practices?

We do the research so you can find trusted products for your health and wellness.

Read more about our vetting process.

Was this helpful?

The normal human body temperature is about 98.6°F, but it fluctuates throughout the day. A low grade fever is when the body temperature rises slightly, usually between about 100.5°F and 102.2°F.

The fever is persistent when the body temperature stays in this range for more than 2 weeks.

A fever is commonly a result of the body trying to fight off an infection or another illness. However, some cases are more difficult to diagnose and treat.

Continue reading to learn more about the symptoms, causes, and treatment of a persistent low grade fever.

Share on PinterestIf the body is fighting off an infection, a person may experience a persistent low grade fever.

Some people may hardly notice that they have a low grade fever. However, others may experience various symptoms, including:

• feeling warm to the touch
• sweating
• chills
• shivering
• headaches
• muscle aches
• dehydration
• a general feeling of being unwell

A persistent low grade fever is typically a sign that the body is fighting off an infection or another health issue and has raised its temperature to help these efforts.

These underlying issues can include:

Respiratory infections

Respiratory infections can cause a persistent low grade fever. Some of the most common respiratory infections, such as a cold or the flu, may cause a low grade fever that lasts for as long as the body takes to fight off the infection.

Other symptoms that may indicate a respiratory infection include:

• coughing
• sneezing
• a stuffy or runny nose
• a sore throat
• chills
• general fatigue
• lack of appetite

Many simple respiratory infections do not require treatment, and the symptoms will go away in time.

Urinary tract infections

A urinary tract infection (UTI) may also be the underlying cause of a low grade fever. A UTI is a bacterial infection that occurs when bacteria multiply anywhere in the urinary tract, which includes the bladder, urethra, kidneys, and ureters.

In addition to a low grade fever, the person may experience symptoms such as:

• pain in the abdomen
• a burning sensation while peeing
• frequent urination
• a constant urge to urinate
• dark urine

Most UTIs are simple to treat with antibiotics. The doctor may analyze a urine sample to determine the precise type of bacteria causing the infection to ensure that they prescribe the right treatment.

Other infections

Share on PinterestA person should talk to their doctor if they experience any symptoms of infection alongside a fever.

Almost any infection can cause a fever. A fever is one of the body’s natural responses to foreign invaders. The body may keep its core temperature elevated while it is fighting off the infection.

Other sources of infections that may cause a low grade fever include:

• food poisoning
• exposure to pathogens from livestock
• tuberculosis
• meningitis

Anyone experiencing symptoms of infection alongside a fever should see a doctor if the symptoms do not improve with rest and time.

Medications

Some medications can cause many different side effects, which may include a low grade fever. People can check the information on side effects and interactions that comes in the packaging or seek advice from a pharmacist.

As the author of a 2018 review notes, if the medication is the cause, the fever should go away very quickly — typically within 72 hours — once the person stops taking the drug.

Stress

Chronic stress may cause a low grade fever. A research paper from 2015 notes that a fever due to stress is most common in young women.

Reducing stress levels may resolve the fever in these cases.

Cancer

In rare cases, a persistent low grade fever with no known cause may be a sign of cancer.

A persistent fever can be a symptom of leukemia, Hodgkin disease, or non-Hodgkin lymphoma.

The person may also experience other symptoms of cancer, including:

• persistent fatigue
• weakness
• headaches
• infections
• lack of appetite
• excessive bruising or bleeding
• unexplained weight loss
• enlarged lymph nodes
• excessive sweating at night

Many of these symptoms are not unique to cancer, however.

Anyone who experiences these symptoms along with a low grade fever should see a doctor for a diagnosis.

Chronic disorders

Many other chronic disorders may cause symptoms such as a low grade fever, including:

• thromboembolic disease
• arthritis
• lupus
• gout
• thyroiditis
• serum sickness-like reactions
• serotonin syndrome
• neuroleptic malignant syndrome

Diagnosing a persistent low grade fever may involve several different tests to eliminate potential causes.

The doctor will generally carry out a physical examination and question the person regarding additional symptoms and whether they have any chronic conditions.

The doctor may also ask about any medications that the person takes so that they can eliminate them as a cause of the fever.

They may order blood tests, such as a complete blood count (CBC), to get an overview of the person’s health. The results may help them decide which other tests, if any, they need to order.

If the doctor suspects that the person has a UTI, they may ask them for a sample of their urine to test.

Share on PinterestOTC drugs may help treat a low grade fever at home.

Treatment for a persistent low grade fever will depend on the cause. For instance, minor infections may not need treatment at all, whereas issues such as cancer require extensive treatment.

To alleviate the symptoms of a low grade fever at home, a person can try over-the-counter (OTC) drugs, such as ibuprofen (Advil) or acetaminophen (Tylenol).

A fever can cause dehydration, so it is vital to drink plenty of water.

It is important to treat a low grade fever in children, who may be more sensitive to temperature changes. Using children’s versions of OTC drugs may help control the fever while waiting to see a doctor.

A persistent low grade fever is a sign of an underlying issue, such as a mild infection or chronic condition. The fever may persist while the person is fighting off the infection.

For the most part, persistent low grade fevers are not a cause for concern. However, it is important to monitor the fever to see whether it gets worse.

Anyone who is concerned about their symptoms or experiences a persistent low grade fever for more than 10 days should see a doctor.

SHOP FOR OTC DRUGS

The drugs listed in this article are available online:

• Ibuprofen
• Acetaminophen

The diagnosis of “fever of unknown origin” is a stumbling block in pediatric infectology

True knowledge is the knowledge of causes.
G. Galileo

Introduction

One of the most difficult problems in medicine is diseases accompanied by prolonged fever, in which the exact diagnosis remains unclear for weeks and even months. Ultimately, the true nature of the disease manifests itself, since the pathological condition that caused a prolonged increase in temperature to 38. 5 ° C and above rarely disappears without giving information about its origin. Clarifying problems of this kind requires the use of all diagnostic methods – a detailed history taking, examination, carefully thought-out use of laboratory research methods.

Recently, infections have been given little importance among the causes of fever of unknown origin, due to the widespread use of antibiotics to treat fever that lasts several days. Thus, most infectious diseases are stopped more or less “blindly”, without an exact definition of their nature and localization. In the 1950s, infectious patients accounted for 40% of the total number of patients with fevers of unknown origin, and in the 70s, the proportion of infectious diseases in similar groups decreased to 32%, but the percentage of tumors increased from 20 to 33 [3]. Many of the infectious agents are relatively resistant to the action of the body’s defenses (for example, focal purulent infections and intracellular infections), which leads to a chronic or subacute course of the disease.

The main syndrome of fever associated with infection in children is usually accompanied by sufficiently clear symptoms that allow at least a preliminary diagnosis to be made directly at the patient’s bedside. But in some patients, fever becomes the dominant symptom, and when the cause of its occurrence is not established, this condition is called a fever of unknown origin (FUN). This term should only be used to characterize diseases with a prolonged (at least 2–3 weeks) rise in temperature above 38.5 °C, if the diagnosis was not made within one week of intensive examination [3, 5]. Such stringent criteria make it possible to exclude from this category patients with well-known bacterial and viral infections with an obvious diagnosis and those in whom fever is the result of etiologically unrelated diseases (chicken pox – phlegmon – sepsis).

A markedly increased flow of long-term febrile sick children (who come for consultations and to the clinic for childhood infections) was the reason for the analysis of the current situation.

Material and research methods

Over the past 4 years, 57 children with fever of unknown origin were referred to the clinic for childhood infections. Among them were 30 boys and 27 girls. 52% of children lived in the city, the rest – in the countryside. The age composition of children was in the range from 1 to 18 years: up to 1 year – 2, 1-3 years – 6, 10 children aged 3-7 and 7-10 years, 19children – 10-14 years old, the rest were over 14 years old. Prior to admission to the clinic, in all the children we observed, the duration of fever was at least 2-3 weeks, maximum 6 months. In most patients, the duration of fever varied from 5 weeks to 4.5 months. At the same time, they received outpatient or inpatient treatment using several courses of antibiotics, corticosteroids, non-steroidal and anti-inflammatory drugs, including infusion therapy. Along with the diagnosis of “fever of unknown origin”, when they were sent to the clinic, the children were diagnosed with various diagnoses with a question mark: adenovirus infection (7), lacunar tonsillitis (2), scarlet fever, felinosis (2), infectious mononucleosis (3), yersineosis (3) . However, the majority of children were only diagnosed with fever of unknown origin. The average number of bed-days was 19.9 ± 4.5. All the children survived, but only 42 children were discharged home healthy. The rest were transferred to specialized departments for further treatment for various diseases established in the clinic.

Suggested standard tests necessary for the situation to be recognized as LDL, according to many authors [1, 3], include: complete clinical blood count, determination of urea level, ionogram, liver tests, markers of inflammation (acute phase tests), crops blood at the height of fever, antistreptolysin titer, serology for viruses (including Epstein-Barr virus), a swab from the oropharynx for viruses and bacteria, an X-ray of the WGC, a general urine test with its microscopy and culture. The presented list of studies was supplemented by us with ultrasound of the abdominal organs, while we were also interested in the state of the retroperitoneal lymph nodes.

The presented scheme of examination, observation of patients in dynamics, combined with a detailed study of the anamnesis of the disease and the patient’s life, made it possible to quickly (within 5–7 days) make the following diagnoses: SARS, sinusitis – 3 children, Stevens-Johnson syndrome – 2, urinary tract infection system – 2, yersineosis – 1, adenovirus infection – 10 children. Diagnosis of such diseases as congenital cytomegalovirus infection (3), viral-bacterial infection (4), juvenile rheumatoid arthritis (1) required a longer time.

Most undiagnosed acute diseases accompanied by fever are of viral origin. They are not detected for the reason that diagnostic methods are not always available, cumbersome, expensive or ineffective. It is not practical to test for all known viruses, as there are a significant number of unidentified viruses that are pathogenic to humans.

Infectious diseases are characterized by:

1) acute onset;

2) an increase in body temperature up to 38. 5-40.6 ° C, sometimes accompanied by chills;

3) symptoms of damage to the upper respiratory tract – pharyngitis, runny nose, cough;

4) severe malaise with pain in the joints and muscles, photophobia, pain when moving the eyeballs, headache;

5) nausea, vomiting, diarrhea;

6) acute enlargement of the lymph nodes or spleen;

7) meningeal syndrome in combination with pleocytosis in the cerebrospinal fluid or without it;

8) the level of leukocytes is above 12,000 or below 5,000 in 1 mm;

9) dysuria, increased urination, pain in the side.

We agree with colleagues [3, 4] that none of the listed symptoms is specific only for infectious diseases. Most of these signs can occur in acute leukemia, SLE, and other diseases. Nevertheless, in the case of acute febrile conditions in the presence of the above symptoms, the development of an infectious process is most likely. And therefore, the authors of the fundamental work “Intermittent fever” recommend convincing the patient of the possibility of recovery within 1 or 2 weeks, regardless of the diagnosis [6]. In fairness, we were in no hurry with encouraging recommendations, since the terms for making a final diagnosis in many patients exceeded a month or more. And one boy at the age of 16 was in the clinic for an examination for LDL for more than 2 months, was transferred to the somatic department with a preliminary diagnosis of “systemic connective tissue disease”, and from there, after an additional examination and observation for a month, he was sent to the city of Kazan. Kiev with a competing diagnosis of “diencephalic syndrome”. The final diagnosis has not yet been made.

In addition to prolonged fever, patients entering the clinic had other fairly common symptoms and complaints: skin rash (10 children), lymphadenopathy of varying severity (52), prolonged bronchitis and pneumonia (19), unstable stools (8), periodic pain in the abdomen without signs of acute intestinal infection (10), tonsillitis (5).

The largest group (14) consisted of children with a confirmed diagnosis of infectious mononucleosis caused by the Epstein-Barr virus. A number of authors point out that the incidence of infectious mononucleosis over the past decade has increased by more than 4 times [1, 2]. In our observations, infectious mononucleosis retained its main features, proceeded, as a rule, in a moderate form. But in isolated cases (in 2 children in the pubertal period) it was necessary to resort to sternal puncture to rule out acute leukemia. Bone marrow aspiration should be considered when examining fever of unknown origin, even if peripheral blood smears are normal, especially before corticosteroids are started because they may mask leukemia [1]. Other features of the course of infectious mononucleosis today include low numbers of atypical mononuclear cells in a clinical blood test (6–15%) in the absence of a complete set of clinical symptoms typical of this disease. Lymphadenopathy in our patients with Epstein-Barr virus infection was, as a rule, non-generalized and was limited to an increase in predominantly submandibular and cervical lymph nodes. However, in 8 children with recurrent (rather severe) abdominal pain, ultrasound revealed enlarged mesenteric lymph nodes. Changes in the oropharynx in all patients were of the type of chronic tonsillitis, and only 5 had tonsillitis with effusion.

There is an opinion that when establishing the causes of fever, you can mainly rely on laboratory data. However, in many cases, a carefully collected history helps to answer this question: details of vaccination, travel with parents (especially to other countries), contact with pets, profession of family members, hobbies of the child, family contacts with infectious patients and, at least approximately, data on the socio-economic status of the family. Repeated examination of the patient (in dynamics), patient observation allow us to make the correct diagnosis even before the start of a variety of expensive laboratory tests. All of the above was related to the diagnosis of “helminthiasis” (in 3 cases – toxocariasis, in 2 – ascariasis). Moreover, according to the established stereotype, the presumptive diagnosis of “helminthiasis” turned out to be the last in the doctor’s diagnostic search.

Attention is drawn to the frequency of damage to the hepatobiliary system in adolescents, which is also reflected in our observations. 13 pubertal children (almost 23%) had confirmed diagnoses of chronic cholecystitis, duodenitis, cholangitis.

At the same time, an excessive focus on the infectious origin of fever should not lead the pediatrician away from the search for other possible causes. And at the present time, the thesis put forward by the internists of the past retains its significance: “The longer the fever lasts, the less likely its infectious origin.”

Due to the widespread use of immunological diagnostic tests, diseases characterized by systemic inflammation of the connective tissue have recently occupied an insignificant place among the causes of fever of unknown origin. Nevertheless, four children (of puberty) were diagnosed with “systemic connective tissue disease”, and therefore they were transferred to somatic departments for further examination and treatment. In one of the children, a comprehensive examination included a puncture skin biopsy, which made it possible to make a diagnosis of dermatomyositis. This is exactly the case when a biopsy is one of the most informative diagnostic tools.

The findings were the following diagnoses: “chronic hepatitis C” (in one patient), “juvenile rheumatoid arthritis” (1), “malformation of cerebral vessels” (1), “herpetic infection” (1), “staphylococcal infection with scarlatiniform syndrome” ( 1).

Conclusion

The diagnosis of “fever of unknown origin” should never be considered final, since it is the basis only for symptomatic therapy, which rarely affects the cause, but can significantly distort other symptoms that are more informative for recognizing the disease.

Most people fall into the category of patients with fever of unknown origin due to errors in the work of the attending physicians, ignoring or rejecting unexplained data. There is no malice here, because doctors, being ordinary people, are far from perfect. There are no algorithms or computers capable of changing this trend; moreover, even new research methods are not sensitive enough to more accurately determine the cause of fever in patients with a variety of atypical pathological processes.

In order to avoid mistakes, repeated examinations and collections of analyzes are required, rethinking of records in the medical history in order to find a clue that is nearby, but not appreciated. There is a need for extensive discussion of problems with colleagues, as well as calm reflection on the clinical puzzle. This does not mean that one should conduct numerous studies, many of which are painful and expensive, load the patient with a large number of drugs and, as a last resort, perform exploratory surgery. Doctors treating a patient with a fever of unknown origin should watch him, talk to him, think about him. There is no substitute for these simple clinical principles. We would like to end our conversation about the difficulty of unraveling the diagnosis of “fever of unknown origin” with the authoritative opinion of the great S. P. Botkin: “When observing a patient, it must be remembered that the diagnosis is a more or less probable hypothesis.”

Hemorrhagic fever with renal syndrome

Hemorrhagic fever with renal syndrome (popularly “mouse fever”) is an acute infectious viral, natural focal disease, accompanied by high fever and impaired renal function.

Perhaps, HFRS is one of the most widespread viral natural focal infections. In Russia, the greatest distribution is noted in the Far East, and in the European part – between the Volga and the Urals (Republics of Bashkortostan, Tatarstan, Udmurtia, Samara and Ulyanovsk regions). Epidemic outbreaks of HFRS are more often recorded in summer and autumn, during the summer and tourist seasons. Up to 85% of HFRS patients are young men (20-40 years old).

Natural foci of HFRS in the territory of Bashkortostan are considered to be one of the most active and largest in the world. This is explained by the fact that in our republic the most active centers are located in linden forests, of which we have plenty. Linden bears fruit annually, and its seeds fall throughout the winter, thus providing abundant food for small rodents.

The source of infection are bank voles and field mice, in which the pathogen is located. In the process of life, mouse-like rodents excrete the pathogen into the external environment along with feces, urine and saliva.

You can become infected by simply inhaling dust with particles of rodent waste products, using contaminated food, water. Infection is likely, even if you simply do not wash your hands after working in the garden or cleaning in a country house or cottage, in the forest when collecting brushwood and picking berries. Through the upper respiratory tract, the virus enters the human lungs, and then the virus spreads through the blood into the vascular endothelium and epithelial cells of a number of organs. The next route of infection is by eating food and water contaminated with secretions from sick mice.

It should be especially noted that HFRS is not transmitted from person to person, that is, an infected person does not pose an epidemiological danger.

The virus is inactivated at 50°C for 30 minutes. Good storage at temperatures below -20°C. Sensitive to ether, chloroform, acetone, benzene, ultraviolet rays.

The disease develops rapidly. The first signs of the disease are fever, chills, fever lasts for 5-7 days, headache, weakness and aching muscles, nausea, and abdominal pain are possible. The appearance of the patients is very characteristic, the face of the patient is like that of a person who has just left the bath, it is purple-red, swollen, redness of the eyes and upper half of the body is noted.

Symptoms usually develop within one to two weeks after infection, rarely up to 7 weeks. With timely treatment, the prognosis is generally favorable. After an acute illness, a stable, lifelong immunity is formed. At the first symptoms, it is necessary to consult a doctor, the sooner treatment begins, the less complications there will be.

To date, there is no vaccine against HFRS, therefore, the main method of preventing HFRS is to carry out systematic sanitary and rodent extermination measures, and to comply with public and personal hygiene measures.