Table 5. PCR and serologic results for patients in study group with acute Q fever and control group with negative serologic results for Q fever, the Netherlands*.
| Characteristic | Study group, n = 82 | Control group, n = 52 | Day of illness for study group, mean ± SD | Day of illness for control group, mean ± SD | Sensitivity, % |
|---|---|---|---|---|---|
| PCR |
|
|
|
|
|
| First sample | 23/41 | 0/15 | 8 ± 7 | 8 ± 7 | 56 |
| Second sample | 1/4 | 0/1 | 12 ± 5 | 30 ± 0 | 25 |
| ELISA | |||||
| First sample | 20/33 | 0/18 | 10 ± 8 | 7 ± 6 | 61 |
| Second sample | 15/18 | 0/2 | 20 ± 11 | 25 ± 8 | 83 |
| CFA | |||||
| First sample | 18/81 | 0/52 | 9 ± 19 | 8 ± 6 | 22 |
| Second sample | 27/34 | 0/28 | 18 ± 9 | 20 ± 12 | 79 |
| Third sample | 5/5 | 0/3 | 21 ± 6 | 26 ± 5 | 100 |
| Culture | |||||
| Blood† | 0/42 (0) | 0/40 (0) | NA | NA | NA |
| Urine† | 0/30 (0) | 0/37 (0) | NA | NA | NA |
| Sputum‡ | 1/15 (7) | 3/22 (14) | NA | NA | NA |
| Chest radiograph§ | 62/79 (78) | 28/52 (54) | NA | NA | ¶ |
*Values are no. positive/no. tested (%) unless otherwise indicated. CFA, complement fixation assay; NA, not applicable. †Includes only results for first cultures obtained after coming to the hospital. ‡Includes only results for first cultures obtained after coming to the hospital. In the study group, 1 patient was positive for parainfluenza virus. In the control group, 1 patient was positive for Moraxella catarrhalis, 1 patient was positive for Legionella pneumophila, and 1 patient was positive for Streptococcus pneumonia and Staphylococcus aureus. §Includes only first chest radiographs after coming to the hospital. Values are no. abnormal/no. tested (%). ¶p = 0.003, by χ2 test.