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ULY CLINIC

25 Mei 2025, 11:20:22

Chills (Rigors)

Definition and Clinical Presentation

Chills, or rigors, are defined as sudden, involuntary, and intense muscle contractions resulting in violent shivering and teeth chattering. These episodes often accompany fever and signal the onset of an underlying infection or systemic inflammatory response. Chills can present in various forms:

Single shaking chill – Common in infections like pneumococcal pneumonia.
Intermittent chills – Typically seen in malaria or Hodgkin's lymphoma (Pel-Ebstein fever).
Prolonged chills (up to 1 hour) – May precede a high fever in systemic infections.

Pathophysiology: Why Chills Occur with Fever

Chills occur due to a reset in the hypothalamic thermoregulatory center:

Exogenous pyrogens (e.g., bacterial endotoxins) stimulate immune cells.
These cells release endogenous pyrogens such as IL-1, IL-6, and TNF-α.
These cytokines act on the hypothalamus to increase the body’s set point.
The body perceives its current temperature as low and initiates heat-generating mechanisms—mainly shivering.
Muscle contractions generate heat, elevating the core temperature to match the new set point, thereby producing fever.

Chills without fever can occur in response to environmental cold exposure or as a reaction to medications, transfusions, or other non-infectious etiologies.

Clinical assessment: History and physical Examination

Key history questions

Onset, frequency, and duration of chills (sudden or progressive? continuous or intermittent?)
Associated symptoms: fever, headache, sore throat, dysuria, diarrhea, nausea, confusion, cough, abdominal pain
Medication history (including antipyretics, recent changes)
Recent infections, chemotherapy, or immunosuppressive treatments
Animal exposure (e.g., birds, rodents, livestock)
Travel history or contact with infected individuals
History of allergies or prior reactions to medications or transfusions

Examination tips

Record a baseline rectal temperature and monitor regularly for fluctuations
Look for signs of localized or systemic infection
Assess for rashes, lymphadenopathy, murmur, respiratory symptoms, abdominal tenderness, joint swelling, or neurologic deficits

Medical conditions associated with chills

Infectious causes

Pneumonia: Often presents with a single shaking chill, fever, productive cough, and pleuritic chest pain.
Malaria: Characterized by cyclical chills, high fever, and profuse sweating—paroxysms vary by Plasmodium species.
Septicemia (Gram-negative bacteremia): Rapid onset chills, fever, GI symptoms, and prostration.
Infective Endocarditis: Intermittent shaking chills, petechiae, Osler nodes, Janeway lesions, new murmur.
Pyelonephritis: High fever, chills, CVA tenderness, dysuria, cloudy urine, systemic signs.
Legionnaires’ Disease: High fever, chills, respiratory symptoms, diarrhea, confusion, and chest radiograph abnormalities.
Rocky Mountain Spotted Fever: Sudden chills, fever, severe headache, myalgia, and characteristic rash.
Plague: Bubonic (lymphadenopathy), pneumonic (respiratory distress), septicemic (shock) forms all produce chills and high fever.
Anthrax (Inhalation): Biphasic presentation—initial flu-like illness followed by rapid respiratory collapse and death if untreated.
Tularemia: Abrupt chills, fever, cough, pleuritic chest pain, and signs of sepsis.
Monkeypox: Chills with fever, lymphadenopathy, and rash resembling smallpox.
Q Fever: Flu-like symptoms with possible hepatitis or pneumonia; highly infectious.
Typhus: Fever, chills, rash, and systemic symptoms following exposure to body lice or fleas.
Violin Spider Bite: Chills, systemic toxicity, rash, and possible delirium.
Snake Bite (pit viper): Chills, hypotension, coagulopathy, necrosis, and systemic signs of envenomation.
Hepatic Abscess: Fever, chills, RUQ pain, nausea, vomiting.
Renal Abscess: Flank pain, CVA tenderness, hematuria, chills, and systemic infection.
Puerperal/Postabortal Sepsis: High fever, chills, uterine tenderness, foul discharge, and systemic signs.
Pelvic Inflammatory Disease: Fever, chills, purulent discharge, adnexal tenderness, and possible tubo-ovarian abscess.
Kawasaki Disease: In children, high spiking fever with mucocutaneous signs, chills, and coronary involvement.

Non-infectious and iatrogenic causes

Hemolytic anemia: Fever, chills, jaundice, hepatosplenomegaly.
Septic arthritis: Chills with painful, swollen joint(s).
Septic shock: Early warm phase with chills and fever; later progression to cold, clammy extremities, hypotension, and organ failure.
Cholangitis: Charcot’s triad—RUQ pain, jaundice, and chills with fever.
Sinusitis: Facial pain, purulent discharge, chills, and fever.
AIDS-related infections: Opportunistic infections often present with chills and systemic symptoms.

Drug-related and iatrogenic causes

Amphotericin B: Commonly causes chills and rigors during infusion.
Bleomycin, phenytoin: May produce drug-induced fever with chills.
IV Therapy-related Infections: Phlebitis and catheter-associated infections often present with local inflammation and systemic signs, including chills.
Blood Transfusion Reactions: Chills may occur due to hemolytic or febrile non-hemolytic reactions during or shortly after transfusion.

Table: Medical causes of chills, categorized by disease, brief description, key symptoms, and special notes (like transmission or complications):

Disease/Condition	Description	Key Symptoms	Special Notes
Acquired Immunodeficiency Syndrome (AIDS)	Fatal disease caused by HIV, transmitted by blood/semen.	Lymphadenopathy, fatigue, anorexia, weight loss, diarrhea, diaphoresis, skin disorders, respiratory infections.	Opportunistic infections common.
Anthrax (Inhalation)	Infection by Bacillus anthracis spores inhaled from environment or biological warfare.	Flulike symptoms (fever, chills, weakness, cough, chest pain), rapid deterioration with dyspnea, stridor, hypotension.	Radiologic: mediastinitis, mediastinal widening; rapid fatal progression in 2nd stage.
Cholangitis	Sudden common bile duct obstruction.	Charcot’s triad: chills, fever, RUQ pain, jaundice; pruritus, weakness, fatigue.
Gram-negative bacteremia	Blood infection by gram-negative bacteria.	Sudden chills, fever, nausea, vomiting, diarrhea, prostration.
Hemolytic anemia (acute)	Rapid destruction of red blood cells.	Fulminating chills, fever, abdominal pain, jaundice, hepatomegaly, splenomegaly.
Hepatic abscess	Abscess in liver.	Abrupt chills, fever, nausea, vomiting, diarrhea, anorexia, severe upper abdominal pain possibly radiating to shoulder.
Infective endocarditis	Infection of heart valves.	Intermittent shaking chills, fever, petechiae, Janeway lesions, Osler nodes, murmur, hematuria, signs of cardiac failure.
Influenza	Viral respiratory infection.	Abrupt chills, high fever, malaise, headache, myalgia, nonproductive cough, rhinitis, sore throat, hoarseness.	Chills subside after a few days; intermittent fever and cough may last ~1 week.
Kawasaki disease	Acute febrile illness in children <5 years.	High spiking fever (≥5 days), chills, irritability, red eyes, strawberry tongue, swollen hands/feet, peeling skin.	Causes coronary artery inflammation; treated with IVIG and aspirin; major cause of acquired heart disease in kids.
Legionnaires’ disease	Legionella bacterial pneumonia.	Sudden chills, high fever, malaise, headache, diarrhea, cough progressing to productive, nausea, vomiting, confusion.
Malaria	Paroxysmal fever caused by Plasmodium spp.	Cyclic chills (1-2 hrs), high fever (3-4 hrs), diaphoresis (2-4 hrs), headache, muscle pain, hepatosplenomegaly.	Paroxysm every 40-72 hrs depending on species.
Monkey pox	Viral disease similar but milder than smallpox.	Fever with chills, sore throat, swollen lymph nodes, cough, rash, muscle aches, exhaustion.	No specific treatment; smallpox vaccine may help prevent or reduce severity.
Pelvic inflammatory disease	Infection of female reproductive organs.	Chills, fever, lower abdominal pain, purulent vaginal discharge, abnormal bleeding, nausea, vomiting, abdominal mass.
Plague (Yersinia pestis)	Severe bacterial infection transmitted by flea bites or respiratory droplets.	Fever, chills, swollen tender lymph nodes (bubonic), headache, myalgia, cough, chest pain, hemoptysis, respiratory distress.	Includes bubonic, septicemic, pneumonic forms; potential for epidemics and biowarfare.
Pneumonia	Lung infection (often pneumococcal).	Sudden shaking chill, fever, productive cough with bloody sputum, pleuritic chest pain, dyspnea, cyanosis, diaphoresis.	Physical exam: bronchial breath sounds, crackles, rhonchi.
Puerperal/postabortal sepsis	Infection after childbirth or abortion.	Chills, high fever (6 hours to 10 days postpartum), purulent vaginal discharge, tender/enlarged uterus, abdominal pain.
Pyelonephritis	Kidney infection.	Chills, high fever, nausea, vomiting, flank pain, CVA tenderness, hematuria, urinary symptoms (frequency, urgency).
Q fever	Rickettsial infection from farm animals or barnyard dust.	Fever, chills, severe headache, malaise, chest pain, nausea, vomiting, diarrhea; may cause hepatitis or pneumonia.	Considered biowarfare agent.
Renal abscess	Abscess in kidney.	Sudden chills, fever, flank pain, CVA tenderness, abdominal muscle spasm, transient hematuria.
Rocky Mountain spotted fever	Rickettsial disease from ticks.	Sudden chills, fever, malaise, severe headache, muscle/joint pain, coated tongue, maculopapular then petechial rash.	Rash begins on hands/feet then spreads.
Septic arthritis	Infection in joints.	Chills, fever, red, swollen, painful joints.
Septic shock	Severe systemic infection causing circulatory collapse.	Initial chills, fever, flushed warm skin; later cold, clammy skin, hypotension, oliguria, confusion, coma.	Rapid progression to multi-organ failure.
Sinusitis	Inflammation/infection of sinuses.	Chills, fever, headache, sinus pain and tenderness, nasal discharge (bloody then purulent).	Pain location depends on sinus affected.
Snake bite (pit viper)	Envenomation causing systemic toxicity.	Chills with fever, sweating, weakness, dizziness, hypotension, local swelling, pain, bleeding, necrosis, respiratory distress.
Tularemia	Infection from Francisella tularensis via insect bites, inhalation, contact.	Abrupt fever, chills, headache, myalgia, cough, dyspnea, pleuritic chest pain, empyema.	Potential biowarfare agent.
Typhus	Rickettsial infection transmitted by fleas, mites, lice.	Headache, myalgia, malaise followed by abrupt chills, fever, nausea, vomiting, sometimes rash.
Violin spider bite	Spider bite causing systemic symptoms.	Chills, fever, malaise, nausea, vomiting, joint pain, rash, delirium within 24-48 hours.

Other Causes
Drugs	Amphotericin B, phenytoin, IV bleomycin, intermittent oral antipyretics can cause chills.	Fever and chills.
IV therapy (infection)	Infection at IV site (phlebitis).	Chills, high fever, local redness, warmth, tenderness.
Transfusion reaction	Hemolytic or nonhemolytic febrile reactions.	Chills during or after transfusion.

Rare Causes
Brucellosis		Undulant fever with chills.
Dengue fever		Breakbone fever with chills.
Epidemic typhus		Louse-borne typhus with chills.
Leptospirosis
Lymphocytic choriomeningitis
Monkey pox
Plague
Pulmonary tularemia
Rat bite fever
Relapsing fever

Age-specific considerations

Pediatric

Infants rarely exhibit chills due to underdeveloped thermoregulatory shivering mechanisms.
Older children may experience chills with infections like mycoplasma pneumonia or osteomyelitis.

Geriatric

In elderly patients, chills are a strong indicator of infection such as:
- UTI
- Pneumonia (especially aspiration-related)
- Diverticulitis
- Pressure ulcer-related sepsis
- Consider ischemic bowel if abdominal pain is also present

Clinical management and monitoring

Vital signs: Monitor closely for signs of septicemia or shock.
Investigations: Obtain appropriate cultures (blood, urine, sputum, wound) and imaging studies.
Treatment:
- Administer empiric antibiotics as indicated.
- Provide antipyretics for fever control—avoid inconsistent dosing which can provoke chills.
- Ensure adequate hydration and nutritional support.

Note: Since chills represent a physiologic attempt to generate heat, covering with blankets may not stop shivering. Maintain a stable ambient temperature and focus on addressing the underlying cause.

Patient education

Inform patients (or caregivers) on:

Importance of temperature monitoring and documenting patterns
Recognizing signs of worsening infection (e.g., persistent fever, altered mental status)
Adherence to prescribed medications, especially antibiotics
When to seek urgent medical care

References

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Kumar V, Abbas AK, Aster JC. Robbins and Cotran Pathologic Basis of Disease. 10th ed. Philadelphia: Elsevier; 2020.
Brunton LL, Hilal-Dandan R, Knollmann BC. Goodman & Gilman's: The Pharmacological Basis of Therapeutics. 14th ed. New York: McGraw Hill; 2022.
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World Health Organization. Malaria fact sheet [Internet]. Geneva: WHO; 2023 [cited 2025 May 25]. Available from: https://www.who.int/news-room/fact-sheets/detail/malaria
Centers for Disease Control and Prevention. Infectious Disease A-Z [Internet]. Atlanta: CDC; 2024 [cited 2025 May 25]. Available from: https://www.cdc.gov