Coxiella/Q Fever

Q fever is a bacterial zoonotic infection caused by Coxiella burnetii. Transmission occurs primarily through the inhalation of contaminated aerosols and exposure to infected animal products. The clinical presentation can vary and often result in mild disease with flu-like symptoms. Other manifestations include pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, hepatitis, endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis, and aseptic meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis. In a small percentage of patients, the disease can become chronic. A high degree of suspicion is required to make the diagnosis, which is aided using serology and PCR. Antibiotics are the mainstay of management.

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General Characteristics of Coxiella

General features of Coxiella

  • Gram-negative organisms
  • Pleomorphic rods
  • Strict intracellular 
  • Aerobic
  • Formerly designated as a Rickettsia Rickettsia Rickettsiae are a diverse collection of obligate intracellular, gram-negative bacteria that have a tropism for vascular endothelial cells. The vectors for transmission vary by species but include ticks, fleas, mites, and lice. Rickettsia
  • Classified as a Gammaproteobacteria

Clinically relevant species

Coxiella burnetii causes Q fever.

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Epidemiology and Pathogenesis

Epidemiology

  • Geographical distribution: 
    • Found worldwide, except in New Zealand
    • In the United States, the highest incidence is in the Midwest and California.
    • More common in rural areas
  • More common in men than women
  • More common in adults than children
  • Higher incidence in spring and summer

Reservoir

  • Ticks (main reservoir)
  • Mammals (including farm animals and pets)
  • Birds

Routes of transmission

  • Inhalation of aerosols
  • Consumption of contaminated milk
  • Intradermal inoculation

Host risk factors

  • Contact with farm animals:
    • Farmers
    • Slaughterhouse workers
    • Veterinary personnel
    • Shepherds
  • Individuals living near farms
  • Laboratory workers

Virulence factors

Antigenic phase variation:

  • Phase I:
    • Highly infectious
    • Contains smooth lipopolysaccharide (LPS)
    • Protects against host defense mechanisms Defense mechanisms Defense mechanisms are normal subconscious means of resolving inner conflicts between an individual's subjective moral sense and their thoughts, feelings, or actions. Defense mechanisms serve to protect the self from unpleasant feelings (anxiety, shame, and/or guilt) and are divided into pathologic, immature, mature, neurotic, and other types. Defense Mechanisms
  • Phase II:
    • Noninfectious
    • Contains rough LPS (lacks terminal O antigen sugars)

Morphological variants:

  • Small-cell variant:
    • Spore-like appearance
    • Metabolically inactive
    • Resistant to environmental stress:
      • Heat
      • Desiccation
      • Chemicals
      • Pressure
  • Large-cell variant:
    • Metabolically active
    • Able to replicate in phagolysosomes

Escape from intracellular killing:

  • Inhibition of cathepsin fusion
  • Superoxide dismutase production

Pathophysiology

  • The organism is most commonly inhaled → phagocytosed by alveolar macrophages
  • Acidification in phagolysosome → transformation of C. burnetii into its metabolically active state (large-cell variant)
  • Replication → host cell rupture → organisms spread systemically, especially to the reticuloendothelial system ( liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver, spleen Spleen The spleen is the largest lymphoid organ in the body, located in the LUQ of the abdomen, superior to the left kidney and posterior to the stomach at the level of the 9th-11th ribs just below the diaphragm. The spleen is highly vascular and acts as an important blood filter, cleansing the blood of pathogens and damaged erythrocytes. Spleen, and bone marrow Bone marrow Bone marrow, the primary site of hematopoiesis, is found in the cavities of cancellous bones and the medullary canals of long bones. There are 2 types: red marrow (hematopoietic with abundant blood cells) and yellow marrow (predominantly filled with adipocytes). Composition of Bone Marrow)
  • Immune response results in non-necrotizing granulomas.
  • Autoantibody production can occur.

Clinical Presentation

Patients may present with a wide range of symptoms, and vary in severity from asymptomatic to severe disease.

Acute Q fever

The incubation period for acute infection is approximately 20 days. Patients may present with any of the following conditions:

  • Asymptomatic disease 
  • Flu-like illness (lasts 1–3 weeks):
    • Abrupt onset of high-grade fever
    • Fatigue
    • Headache with photophobia
    • Myalgias
    • Anorexia
  • Pneumonia (lasts 10–90 days):
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
    • Nonproductive cough
    • Acute respiratory distress
    • Pleuritic chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
  • Hepatitis (granulomatous):
    • Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever
    • Hepatomegaly
    • RUQ abdominal pain
    • Nausea and vomiting
    • Diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea
    • Transaminitis
  • Cardiac involvement:
    • Acute endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis (autoimmune)
    • Pericarditis Pericarditis Pericarditis is an inflammation of the pericardium, often with fluid accumulation. It can be caused by infection (often viral), myocardial infarction, drugs, malignancies, metabolic disorders, autoimmune disorders, or trauma. Acute, subacute, and chronic forms exist. Pericarditis
    • Myocarditis Myocarditis Myocarditis is an inflammatory disease of the myocardium, which may occur alone or in association with a systemic process. There are numerous etiologies of myocarditis, but all lead to inflammation and myocyte injury, most often leading to signs and symptoms of heart failure. Myocarditis
  • Neurological involvement:
    • Aseptic meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis
    • Encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis
    • Peripheral neuropathy

Chronic Q fever

Chronic infection may manifest months or years after an acute infection.

  • Endocarditis (culture negative):
    • Low-grade fever
    • Night sweats
    • Fatigue
    • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
    • Septic thromboembolism
    • Heart failure
  • Pericardial effusion Pericardial effusion Pericardial effusion is the accumulation of excess fluid in the pericardial space around the heart. The pericardium does not easily expand; thus, rapid fluid accumulation leads to increased pressure around the heart. The increase in pressure restricts cardiac filling, resulting in decreased cardiac output and cardiac tamponade. Pericardial Effusion and Cardiac Tamponade
  • Chronic hepatitis
  • Osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis
  • Septic arthritis Septic arthritis Septic arthritis is an infection of the joint due to direct inoculation, contiguous extension, or hematogenous spread of infectious organisms into the joint space. This process causes an acute, inflammatory, monoarticular arthritis. Septic Arthritis
  • Mononeuritis
  • Interstitial fibrosis
  • Pseudotumors
  • Glomerulonephritis

Complications

Q fever in pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-hCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care is associated with:

  • Spontaneous abortion Spontaneous abortion Spontaneous abortion, also known as miscarriage, is the loss of a pregnancy before 20 weeks' gestation. However, the layperson use of the term "abortion" is often intended to refer to induced termination of a pregnancy, whereas "miscarriage" is preferred for spontaneous loss. Spontaneous Abortion
  • Intrauterine fetal growth restriction Fetal growth restriction Fetal growth restriction (FGR), also known as intrauterine fetal growth restriction (IUGR), is an estimated fetal weight (EFW) or abdominal circumference < 10th percentile for gestational age. The term small for gestational age (SGA) is sometimes erroneously used interchangeably with FGR. Fetal Growth Restriction
  • Premature delivery

Diagnosis

Q fever lacks a distinct clinical presentation; therefore, the diagnosis relies on a high index of suspicion based on the patient’s risk factors.

Laboratory evaluation

Diagnostic testing:

  • Indirect immunofluorescence for IgG and IgM (high sensitivity and specificity)
  • PCR to detect C. burnetii DNA DNA The molecule DNA is the repository of heritable genetic information. In humans, DNA is contained in 23 chromosome pairs within the nucleus. The molecule provides the basic template for replication of genetic information, RNA transcription, and protein biosynthesis to promote cellular function and survival. DNA Types and Structure
  • Cultures:
    • Does not grow in routine cultures
    • Requires special biosafety containment due to its infectivity

Supporting evaluation:

  • Normal WBC count (90% of cases)
  • Thrombocytopenia Thrombocytopenia Thrombocytopenia occurs when the platelet count is < 150,000 per microliter. The normal range for platelets is usually 150,000-450,000/µL of whole blood. Thrombocytopenia can be a result of decreased production, increased destruction, or splenic sequestration of platelets. Patients are often asymptomatic until platelet counts are < 50,000/µL. Thrombocytopenia
  • ↑ ALT and AST → hepatitis
  • Associated autoantibodies:
    • Antiphospholipid antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins
    • Lupus anticoagulant
  • Liver biopsy → granulomatous changes

Imaging

  • Chest X-ray: consolidation, pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia
  • Echocardiography: vegetation on a heart valve → endocarditis Endocarditis Endocarditis is an inflammatory disease involving the inner lining (endometrium) of the heart, most commonly affecting the cardiac valves. Both infectious and noninfectious etiologies lead to vegetations on the valve leaflets. Patients may present with nonspecific symptoms such as fever and fatigue. Endocarditis
  • Ultrasound: hepatomegaly → granulomatous hepatitis

Management and Prevention

Management

Antibiotic therapy includes:

  • Doxycycline (preferred)
  • Trimethoprim Trimethoprim The sulfonamides are a class of antimicrobial drugs inhibiting folic acid synthesize in pathogens. The prototypical drug in the class is sulfamethoxazole. Although not technically sulfonamides, trimethoprim, dapsone, and pyrimethamine are also important antimicrobial agents inhibiting folic acid synthesis. The agents are often combined with sulfonamides, resulting in a synergistic effect. Sulfonamides and Trimethoprim-sulfamethoxazole
  • Clarithromycin
  • Fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
  • Hydroxychloroquine may be added to doxycycline in patients with:
    • Cardiovascular involvement
    • Chronic Q fever

Prevention

  • Human vaccines:
    • Recommended for individuals with occupational risk
    • Contraindicated in previously exposed individuals
  • Animal vaccines to reduce bacterial shedding
  • Proper disposal of placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity and birth products
  • Avoid unpasteurized milk products
  • Routine testing of animals
  • Quarantine imported animals

Comparison with Similar Gammaproteobacteria

Table: Comparison of similar bacterial species and diseases
Organism Coxiella burnetii Legionella Legionella Legionella is a facultative intracellular, gram-negative bacilli. Legionella does not grow on common culture media because it requires certain supplementation (cysteine and iron). Legionella pneumophila (L. pneumophila) accounts for the majority of human infections. Legionella/Legionellosis pneumophila Francisella tularensis
Characteristics
  • Gram negative
  • Pleomorphic
  • Aerobic
  • Spore-like formation
  • Gram negative
  • Pleomorphic
  • Aerobic
  • Non-spore-forming organisms
  • Flagellated
  • Gram negative
  • Pleomorphic
  • Aerobic
  • Non-spore-forming organisms
Reservoir
  • Ticks
  • Mammals
  • Birds
Aquatic
  • Ticks
  • Mammals
  • Birds
Transmission
  • Inhalation of aerosols
  • Contact with contaminated animal products
  • Inhalation of aerosols
  • Aspiration
  • Via ticks
  • Contact with contaminated animal products
  • Inhalation of aerosols
Clinical presentation Q fever
  • Legionnaires disease
  • Pontiac fever
Tularemia
Diagnosis
  • Serology
  • PCR
  • Urinary antigen
  • PCR
  • Culture
  • Culture
  • Serology
  • PCR
Management Doxycycline
  • Fluoroquinolones Fluoroquinolones Fluoroquinolones are a group of broad-spectrum, bactericidal antibiotics inhibiting bacterial DNA replication. Fluoroquinolones cover gram-negative, anaerobic, and atypical organisms, as well as some gram-positive and multidrug-resistant (MDR) organisms. Fluoroquinolones
  • Macrolides Macrolides Macrolides and ketolides are antibiotics that inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit and blocking transpeptidation. These antibiotics have a broad spectrum of antimicrobial activity but are best known for their coverage of atypical microorganisms. Macrolides and Ketolides
Streptomycin

Differential Diagnosis

  • Lyme disease Lyme disease Lyme disease is a tick-borne infection caused by the gram-negative spirochete Borrelia burgdorferi. Lyme disease is transmitted by the black-legged Ixodes tick (known as a deer tick), which is only found in specific geographic regions. Patient presentation can vary depending on the stage of the disease and may include a characteristic erythema migrans rash. Lyme Disease: an infection caused by Borrelia Borrelia Borrelia are gram-negative microaerophilic spirochetes. Owing to their small size, they are not easily seen on Gram stain but can be visualized using dark-field microscopy, Giemsa, or Wright stain. Spirochetes are motile and move in a characteristic spinning fashion due to axial filaments in the periplasmic space. Borrelia burgdorferi, which is transmitted by the Ixodes tick. Presentation depends on the stage of the disease and may include a characteristic erythema migrans rash. A rash is generally not seen in Q fever. Neurological, cardiac, ocular, and joint manifestations are also common in later stages. Diagnosis relies on clinical findings and tick exposure, and is supported by serological testing. Antibiotics, including doxycycline and ceftriaxone, are used for treatment. 
  • Rocky Mountain spotted fever Rocky Mountain Spotted Fever Rocky Mountain spotted fever (RMSF) is a bacterial infection caused by the obligate intracellular parasite Rickettsia rickettsii. Transmission occurs through an arthropod vector, most commonly the American dog tick (Dermacentor variabilis). Early signs and symptoms of RMSF are nonspecific and include a high fever, severe headache, and rash. Rocky Mountain Spotted Fever: a tick-borne disease caused by Rickettsia Rickettsia Rickettsiae are a diverse collection of obligate intracellular, gram-negative bacteria that have a tropism for vascular endothelial cells. The vectors for transmission vary by species but include ticks, fleas, mites, and lice. Rickettsia rickettsii. Patients present with a classic triad of fever, headache, and rash. A rash is generally not present in Q fever. Other symptoms include malaise, GI distress, and neurological symptoms of confusion, lethargy, and stupor. Diagnosis is made based on clinical features, biopsy of the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin rash, and serological testing. Management involves antibiotics, usually doxycycline.
  • Ehrlichiosis Ehrlichiosis Ehrlichiosis is a tick-borne bacterial infection. The most common causative species include Ehrlichia chaffeensis, which infect and multiply within monocytes. The clinical presentation can vary widely, but often includes fever, malaise, headache, myalgia, and arthralgias. Ehrlichiosis and Anaplasmosis and anaplasmosis Anaplasmosis Anaplasmosis is a tick-borne bacterial infection. The most common causative species include Anaplasma phagocytophilum, which infect and multiply within granulocytes. The clinical presentation can vary widely, but often includes fever, malaise, headache, myalgia, and arthralgias. Ehrlichiosis and Anaplasmosis: tick-borne infections caused by Ehrlichia chaffeensis and Anaplasmosis phagocytophilum, respectively. Symptoms include fever, headache, and malaise. A rash is uncommon, but petechial or maculopapular rashes Rashes Rashes are a group of diseases that cause abnormal coloration and texture to the skin. The etiologies are numerous but can include irritation, allergens, infections, or inflammatory conditions. Rashes that present in only 1 area of the body are called localized rashes. Generalized rashes occur diffusely throughout the body. Generalized and Localized Rashes can occur. The diagnosis is made using PCR, which differentiates these diseases from Q fever. Management of both diseases is with doxycycline.
  • Babesiosis Babesiosis Babesiosis is an infection caused by a protozoa belonging to the genus, Babesia. The most common Babesia seen in the United States is B. microti, which is transmitted by the Ixodes tick. The protozoa thrive and replicate within host erythrocytes. Lysis of erythrocytes and the body's immune response result in clinical symptoms. Babesia/Babesiosis: a tick-borne infection caused by Babesia Babesia Babesiosis is an infection caused by a protozoa belonging to the genus, Babesia. The most common Babesia seen in the United States is B. microti, which is transmitted by the Ixodes tick. The protozoa thrive and replicate within host erythrocytes. Lysis of erythrocytes and the body's immune response result in clinical symptoms. Babesia/Babesiosis. Patients can be asymptomatic or develop fever, fatigue, malaise, and arthralgias. Asplenic, immunocompromised, and elderly patients are at risk for severe disease, causing hemolytic anemia Hemolytic Anemia Hemolytic anemia (HA) is the term given to a large group of anemias that are caused by the premature destruction/hemolysis of circulating red blood cells (RBCs). Hemolysis can occur within (intravascular hemolysis) or outside the blood vessels (extravascular hemolysis). Hemolytic Anemia, thrombocytopenia, hepatosplenomegaly, renal failure, and death. Diagnosis is confirmed with a peripheral blood smear, serological testing, and PCR. Management includes antibiotics, such as atovaquone plus azithromycin.
  • Brucellosis Brucellosis Brucellosis (also known as undulant fever, Mediterranean fever, or Malta fever) is a zoonotic infection that spreads predominantly through ingestion of unpasteurized dairy products or direct contact with infected animal products. Clinical manifestations include fever, arthralgias, malaise, lymphadenopathy, and hepatosplenomegaly. Brucella/Brucellosis: a zoonotic infection caused by several species of Brucella Brucella Brucellosis (also known as undulant fever, Mediterranean fever, or Malta fever) is a zoonotic infection that spreads predominantly through ingestion of unpasteurized dairy products or direct contact with infected animal products. Clinical manifestations include fever, arthralgias, malaise, lymphadenopathy, and hepatosplenomegaly. Brucella/Brucellosis that spreads predominantly through ingestion or direct contact with infected animal products. Clinical manifestations include fever, arthralgias, malaise, lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy, and hepatosplenomegaly. The history, presentation, serology, and culture data are used in the diagnosis. Brucellosis Brucellosis Brucellosis (also known as undulant fever, Mediterranean fever, or Malta fever) is a zoonotic infection that spreads predominantly through ingestion of unpasteurized dairy products or direct contact with infected animal products. Clinical manifestations include fever, arthralgias, malaise, lymphadenopathy, and hepatosplenomegaly. Brucella/Brucellosis can be differentiated from Q fever based on serology. Management involves a combination of antibiotics, including doxycycline, rifampin, and aminoglycosides Aminoglycosides Aminoglycosides are a class of antibiotics including gentamicin, tobramycin, amikacin, neomycin, plazomicin, and streptomycin. The class binds the 30S ribosomal subunit to inhibit bacterial protein synthesis. Unlike other medications with a similar mechanism of action, aminoglycosides are bactericidal. Aminoglycosides
  • Infectious mononucleosis Mononucleosis Infectious mononucleosis (IM), also known as "the kissing disease," is a highly contagious viral infection caused by the Epstein-Barr virus. Its common name is derived from its main method of transmission: the spread of infected saliva via kissing. Clinical manifestations of IM include fever, tonsillar pharyngitis, and lymphadenopathy. Mononucleosis: a disease caused by the Epstein-Barr virus Epstein-Barr Virus Epstein-Barr virus (EBV) is a linear, double-stranded DNA virus belonging to the Herpesviridae family. This highly prevalent virus is mostly transmitted through contact with oropharyngeal secretions from an infected individual. The virus can infect epithelial cells and B lymphocytes, where it can undergo lytic replication or latency. Epstein-Barr Virus, which is characterized by fever, fatigue, lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy, and pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis. Diagnosis is based on clinical features and testing, which includes a heterophile antibody test or serology. Clinical presentation and serology help differentiate mononucleosis Mononucleosis Infectious mononucleosis (IM), also known as "the kissing disease," is a highly contagious viral infection caused by the Epstein-Barr virus. Its common name is derived from its main method of transmission: the spread of infected saliva via kissing. Clinical manifestations of IM include fever, tonsillar pharyngitis, and lymphadenopathy. Mononucleosis from Q fever. Management is supportive. 
  • Viral hepatitis: liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation caused by the hepatitis virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview. Patients may present with a viral prodrome of fever, anorexia, and nausea. Right upper quadrant abdominal pain, jaundice Jaundice Jaundice is the abnormal yellowing of the skin and/or sclera caused by the accumulation of bilirubin. Hyperbilirubinemia is caused by either an increase in bilirubin production or a decrease in the hepatic uptake, conjugation, or excretion of bilirubin. Jaundice, and transaminitis may also occur. The diagnosis is made based on viral serological testing, which helps differentiate viral hepatitis from Q fever. Management of acute hepatitis is supportive.

References

  1. Marrie, T.J. (2010). Q fever pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia. Infect Dis Clin North Am. https://reference.medscape.com/medline/abstract/20171543
  2. Marrie, T.J., Raoult, D. (2005). Coxiella burnetii (Q fever). Mandell GL, Bennett JE, Dolin R, Eds. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia, Pa: Churchill Livingstone.
  3. Marrie, T.J., Stein, A., Janigan, D., Raoult, D. (1996). Route of infection determines the clinical manifestations of acute Q fever. J Infect Dis. https://reference.medscape.com/medline/abstract/8568318
  4. Hartzell, J.D., Wood-Morris, R.N., Martinez, L.J., Trotta, R.F. (2008). Q fever: Epidemiology, diagnosis, and treatment. Mayo Clin Proc. https://reference.medscape.com/medline/abstract/18452690
  5. Terheggen, U., Leggat, P.A. (2007). Clinical manifestations of Q fever in adults and children. Travel Med Infect Dis. https://reference.medscape.com/medline/abstract/17448942
  6. Cleveland, K.O. (2019). Q fever. In Brusch, J.L. (Ed.), Medscape. Retrieved April 9, 2021, from https://emedicine.medscape.com/article/227156-overview
  7. Neupane, K., Kaswan, D. (2020). Coxiella burnetii. [online] StatPearls. Retrieved April 9, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK557893/
  8. Petri, Jr., W.A. (2020). Q fever. [online] MSD Manual Professional Version. Retrieved April 9, 2021, from https://www.msdmanuals.com/professional/infectious-diseases/rickettsiae-and-related-organisms/q-fever
  9. Raoult, D. (2019). Microbiology and epidemiology of Q fever. In Mitty, J. (Ed.), UpToDate. Retrieved April 9, 2021, from https://www.uptodate.com/contents/microbiology-and-epidemiology-of-q-fever
  10. Raoult, D. (2020). Clinical manifestations and diagnosis of Q fever. In Mitty, J. (Ed.), UpToDate. Retrieved April 9, 2021, from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-q-fever
  11. Raould, D. (2020). Treatment and prevention of Q fever. In Mitty, J. (Ed.), UpToDate. Retrieved April 9, 2021, from https://www.uptodate.com/contents/treatment-and-prevention-of-q-fever

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