Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Ahmed Younes M.B.B.CH [2]
Overview
Q fever must be differentiated from other diseases that cause atypical pneumonia such as mycoplasma pneumonia and legionella pneumonia.
Differentiating Q fever from other diseases
Q fever must be differentiated from other diseases that cause atypical pneumonia such as mycoplasma pneumonia and legionella pneumonia.
| Disease
|
Prominent clinical features
|
Lab findings
|
Chest X ray
|
| Q fever
|
- Q fever is characterized by abrupt onset of fever, myalgia, headache and other constitutional symptoms.
- Cough is the most prominent respiratory symptom and it is usually dry.
- Cough is associated with dyspnea and pleuritic chest pain.
|
- Antibody detection using Indirect immunofluorescence (IIF) is the preferred method for diagnosis.
- PCR can be used if IIF is negative or very early once disease is suspected.
- C. brutenii doesn’t grow on ordinary blood cultures but can be cultivated on special media as embryonated eggs or cell culture.
- 2-3 fold increase in AST and ALT is seen in most of the patients.
|
 Q fever pneumonia - - Case courtesy of Royal Melbourne Hospital Respiratory, Radiopaedia.org, rID 21993
|
| Mycoplasma pneumonia
|
- Mycoplasma pneumonia can be asymptomatic
- Headache, nausea and malaise usually precede the onset of symptoms
- Cough which is intractable and nonproductive
|
- Postitve coomb’s test
- Leukocytosis
- Thrombocytosis
|
 Mycoplasma pneumonia - Case courtesy of Dr Alborz Jahangiri, Radiopaedia.org, rID 45781
|
| Legionella pneumonia
|
- Legionella pneumonia is characterized by cough that is slightly productive
- Constitutional symptoms such as chills, myalgia, arthralgia
- Gastrointestinal symptoms such as diarrhea, nausea and vomiting.
|
- Labs are non specific for diagnosing legionella pneumonia
- Renal and hepatic dysfunction
- Thrombocytopenia and leucocytosis
- Hyponatraemia
|
 Legionella pneumonia - Case courtesy of Dr Henry Knipe, Radiopaedia.org, rID 31816
|
| Chlamydia pneumonia
|
- There are no specific clinical features for chlamydia pneumonia.
- Symptoms appear gradually.
- Chlamydia infection is usually associated with upper respiratory tract symptoms (pharyngitis, sinusitis, etc).
- It might be associated with extrapulmonary manifestaions as meningitis and guillain barre syndrome.
|
- Chlamydia pneumonia is usually associated with normal WBC count.
- It's diagnosed with the presence of antichlamydial antibody (through complement fixation or direct immunofluoroscence) or direct antigen detection.
|
 Chlamydia-pneumonia - Case courtesy of Dr Andrew Dixon, Radiopaedia.org, rID 14567
|
References
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