Table 2.
Diagnostic features of the zoonotic atypical pneumonias
| Key Characteristics | Psittacosis | Q fever | Tularemia |
|---|---|---|---|
| Symptoms | |||
| Mental confusion | − | ± | − |
| Prominent headache | + | + | + |
| Meningismus | − | − | − |
| Myalgias | + | + | + |
| Ear pain | − | − | − |
| Pleuritic pain | ± | ± | ± |
| Abdominal pain | − | − | − |
| Diarrhea | − | − | − |
| Signs | |||
| Rash | ±a | − | − |
| Nonexudative pharyngitis | − | − | ± |
| Hemoptysis | − | − | ± |
| Lobar consolidation | + | + | + |
| Cardiac involvement | ±b | ±c | − |
| Splenomegaly | + | + | − |
| Relative bradycardia | + | + | − |
| Chest radiograph | |||
| Infiltrates | Patchy or consolidation | Patchy or consolidation | “Ovoid” or round infiltrates |
| Bilateral hilar adenopathy | − | − | ± |
| Pleural effusion | − | − | Bloody |
| Laboratory abnormalities | |||
| WBC count | ↓ | ↑/N | ↑/N |
| Acute thrombocytosis | − | + | − |
| ↓ Na+ | ± | ± | ± |
| Hypophosphatemia | − | − | − |
| ↑ AST/ALT | + | + | − |
| ↑ Cold agglutinins | − | ± | − |
| ASM antibodies | − | ± | − |
| Microscopic hematuria | − | − | − |
| Diagnostic tests | |||
| Direct isolation (culture) | − | − | − |
| Serology (specific) | CF | CF | TA |
Abbreviations: ASM, anti-smooth muscle; CF, complement fixation; N, normal; TA, tube agglutinins; WBC, white blood cells; +, usually present; ±, sometimes presents; −, usually absent; ↑, increased; ↓, decreased; ↑↑↑, markedly increased.
Adapted from Cunha BA, editor. Pneumonia essentials. 3rd edition. Sudbury (MA): Jones & Bartlett; 2010.
a
Horder's spots (facial spots) resemble the abdominal rash of typhoid fever (Rose spots).
b
Myocarditis.
c
Endocarditis.