Fever of unclear genesis

Sometimes there are cases when a patient's body temperature rises (over 38° C) practically against the background of complete health. Such a condition may be the only sign of the disease, and numerous studies do not allow to determine any pathology in the body. In this situation, the doctor, as a rule, makes a diagnosis - fever of unknown genesis, and then prescribes a more detailed examination of the body.

ICD 10 code

Fever of unknown etiology R50 (except puerperal and postpartum fever, as well as fever of the newborn).

• R 50.0 – fever accompanied by chills.
• R 50.1 – persistent fever.
• R 50.9 – unstable fever.

Causes of fever of unknown genesis

• Systemic extensive infectious diseases:
  • tuberculosis;
  • typhus diseases (typhus, typhoid, endemic, etc.);
  • salmonella, shigella infection;
  • Malta fever (brucellosis);
  • yersiniosis, chlamydia;
  • borreliosis;
  • Francis disease (tularemia);
  • syphilitic infection;
  • leptospirosis;
  • malarial disease;
  • cytomegalovirus, toxoplasma, histoplasma, mononucleosis;
  • AIDS;
  • sepsis.
• Localized infectious diseases:
  • inflammation of the endocardium, thrombotic inflammation of blood vessels;
  • abscesses, bronchiectasis;
  • hepatitis, cholangitis;
  • infectious lesions of the urinary tract and genital area;
  • osteomyelitis, dental infectious diseases.
• Tumor processes:
  • malignant diseases of the blood or lymph (leukemia, lymphogranulomatosis);
  • tumors of the liver, kidneys, lungs, digestive system;
  • tumor metastasis.
• Connective tissue pathologies:
  • granulomatosis;
  • SKV;
  • rheumatism;
  • periarteritis.
• Drug-induced syndromes (malignant hyperthermia, extrapyramidal disorders).
• Pathologies of the digestive organs (ulcerative inflammatory bowel disease, alcohol intoxication, cirrhosis).
• Sarcoidosis.

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Symptoms of fever of unknown origin

The main (and often the only) present symptom of fever of unknown genesis is an increase in temperature. Over a long period, an increase in temperature can be observed without accompanying symptoms, or occur with chills, increased sweating, cardiac pain, and shortness of breath.

• An increase in temperature values is definitely present.
• The type of temperature increase and temperature characteristics are usually of little help in revealing the picture of the disease.
• Other symptoms that usually accompany a rise in temperature (headache, drowsiness, body aches, etc.) may be present.

Temperature readings may vary depending on the type of fever:

• subfebrile (37-37.9°C);
• febrile (38-38.9°C);
• pyretic (39-40.9°C);
• hyperpyretic (41°C>).

Prolonged fever of unknown genesis can be:

• acute (up to 2 weeks);
• subacute (up to one and a half months);
• chronic (more than one and a half months).

Fever of unknown origin in children

A child's temperature is the most common problem that people see a pediatrician about. But what temperature in children should be considered a fever?

Doctors distinguish fever from simply high temperature, when readings exceed 38°C in infants and above 38.6°C in older children.

In most small patients, fever is associated with a viral infection, a smaller percentage of children suffer from inflammatory diseases. Often, such inflammations affect the urinary system, or latent bacteremia is observed, which can later be complicated by sepsis and meningitis.

Most often, the following bacteria become the causative agents of microbial infections in childhood:

• streptococci;
• gram (-) enterobacteria;
• listeria;
• Haemophilus influenzae infection;
• staphylococci;
• salmonella.

Most often, microbial infections affect children in the first six months of life: premature newborns are especially susceptible to such diseases.

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Diagnosis of fever of unknown genesis

According to the results of laboratory tests:

• general blood test – changes in the number of leukocytes (in case of purulent infection – shift in the leukocyte formula to the left, in case of viral infection – lymphocytosis), acceleration of ESR, changes in the number of platelets;
• general urine analysis – leukocytes in urine;
• blood biochemistry – increased CRP, increased ALT, AST (liver disease), fibrinogen D-dimer (PE);
• Blood culture - demonstrates the possibility of bacteremia or septicemia;
• urine culture – to exclude renal tuberculosis;
• bacterial culture of bronchial mucus or feces (as indicated);
• bacterioscopy - if malaria is suspected;
• diagnostic complex for tuberculosis infection;
• serological reactions – if syphilis, hepatitis, coccidioidomycosis, amebiasis, etc. are suspected;
• AIDS test;
• thyroid examination;
• examination for suspected systemic connective tissue diseases.

According to the results of instrumental studies:

• radiograph;
• tomographic studies;
• skeletal system scanning;
• ultrasound examination;
• echocardiography;
• colonoscopy;
• electrocardiography;
• bone marrow puncture;
• biopsies of lymph nodes, muscle or liver tissue.

The diagnostic algorithm for fever of unknown genesis is developed by the doctor on an individual basis. For this, at least one additional clinical or laboratory symptom is determined in the patient. This may be a joint disease, low hemoglobin levels, enlarged lymph nodes, etc. The more such auxiliary signs are detected, the easier it will be to establish the correct diagnosis, narrowing the range of suspected pathologies and determining targeted diagnostics.

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Differential diagnosis of fever of unknown genesis

Differential diagnosis is usually divided into several main subgroups:

• infectious diseases;
• oncology;
• autoimmune pathologies;
• other diseases.

When differentiating, attention is paid not only to the patient’s symptoms and complaints at the moment, but also to those that were present before but have already disappeared.

It is necessary to take into account all illnesses that preceded the fever, including surgeries, injuries, and psycho-emotional states.

It is important to clarify hereditary characteristics, the possibility of taking any medications, the subtleties of the profession, recent travels, information about sexual partners, and animals present in the home.

At the very beginning of the diagnosis, it is necessary to exclude the intentionality of the febrile syndrome - cases of deliberate introduction of pyrogenic agents and manipulations with a thermometer are not so rare.

Skin rashes, heart problems, enlarged and painful lymph nodes, and signs of fundus abnormalities are of great importance.

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Treatment of fever of unknown genesis

Experts do not recommend blindly prescribing medications for fever of unknown genesis. Many doctors rush to apply antibiotic therapy or treatment with corticosteroids, which can blur the clinical picture and complicate further reliable diagnosis of the disease.

Despite everything, most doctors agree that it is important to establish the causes of the feverish condition using all possible methods. And until the cause is established, symptomatic therapy should be carried out.

As a rule, the patient is hospitalized, sometimes isolated if an infectious disease is suspected.

In case of persistent temperature increase, it is recommended to drink plenty of fluids. Avoid eating highly allergenic foods (citrus fruits, chocolate, etc.).

Medication may be prescribed based on the underlying disease that has been detected. If no underlying disease has been detected (which happens in approximately 20% of patients), the following medications may be prescribed:

• antipyretic drugs - non-steroidal anti-inflammatory drugs (indomethacin 150 mg per day or naproxen 0.4 mg per day), paracetamol;
• the initial stage of taking antibiotics is the penicillin series (gentamicin 2 mg/kg three times a day, ceftazidime 2 g intravenously 2-3 times a day, azlin (azlocillin) 4 g up to 4 times a day);
• if antibiotics do not help, they begin taking stronger drugs - cefazolin 1 g intravenously 3-4 times a day;
• amphotericin B 0.7 mg/kg per day, or fluconazole 400 mg per day intravenously.

Treatment continues until the general condition is completely normalized and the blood picture stabilizes.

Prevention of fever of unknown genesis

Preventive measures consist of timely detection of diseases that may later cause an increase in temperature. Of course, it is equally important to competently treat the detected pathologies, based on the doctor's recommendations. This will help avoid many adverse effects and complications, including fever of unknown genesis.

What other rules should be followed to avoid illness?

• Contact with carriers and sources of infection should be avoided.
• It is important to strengthen the immune system, increase the body's resistance, eat well, take enough vitamins, remember about physical activity and follow the rules of personal hygiene.
• In some cases, specific prevention in the form of vaccinations and inoculations may be used.
• It is advisable to have a regular sexual partner, and in case of casual relationships, barrier methods of contraception should be used.
• When traveling to other countries, you should avoid eating unknown foods and products, strictly observe the rules of personal hygiene, do not drink raw water and do not eat unwashed fruits.

Prognosis of fever of unknown genesis

The prognosis of the disease directly depends on its cause, as well as the age and general condition of the patient. Statistical data on the one-year survival rate for fever of unknown etiology are as follows:

• more than 90% for patients under 35 years of age;
• more than 80% for patients aged 35 to 64 years;
• about 70% for patients over 64 years old.

The most unfavorable prognosis is observed in children and the elderly, but a clear percentage ratio and statistical information on this issue have not been obtained.

Fever of unknown genesis requires a specific approach and often non-standard treatment regimens. Control and supervision by a specialist during the course of therapy is mandatory - this, above all, is the key to a speedy recovery.

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