Table 8. Diagnostic methods used to diagnose human ehrlichiosis.
| Diagnostic method | Level of diagnostic certainty* | Human ehrlichiosis CRID [n = 413] | Human ehrlichiosis CRNID [n = 814] | ||
|---|---|---|---|---|---|
| Number of cases tested positive by this method n (%)# | Number of cases for which this level of diagnostic certainty was the highest n (%) | Number of cases tested positive by this method n (%)# | Number of cases for which this level of diagnostic certainty was the highest n (%) | ||
| PCR | A+ | 216 (52.3) | 219 (53) | 432 (53.1) | 432 (53.1) |
| Culture | 3 (<1) | 14 (1.7) | |||
| Immunostaining of biopsy tissue | 16 (3.9) | - | |||
| Serology–IgG IFA, paired samples | A | 109 (26.4) | 92 (22.3) | 341 (41.9) | 308 (37.8) |
| Microscopy | B+ | 53 (12.8) | 12 (2.9) | 13 (1.6) | 2 (<1) |
| Serology–IgG IFA, single sample | B | 50 (12.1) | 33 (8.0) | 86 (10.6) | 69 (8.5) |
| Serology–IgG ELISA, single sample | - | - | |||
| Serology–IgM IFA or ELISA | C | 8 (1.9) | 53 (12.8) | - | 3 (<1) |
| Serology–method not specified | 70 (16.9) | 28 (3.4) | |||
| Clinical diagnosis | D | 4 (<1) | 4 (1) | - | - |
CRID, cases reported with individual data; CRNID, cases reported with non-individual data; ELISA, enzyme-linked immunosorbent assay; IFA, immunofluorescence assay; PCR, polymerase chain reaction.
* A+, diagnosed by PCR, culture and/or immunostaining of biopsy/autopsy tissue; A, diagnosed by paired IgG IFA serology; B+, diagnosed by microscopy of blood smear or buffy coat preparation; B, diagnosed by single IgG IFA or ELISA serology; C, diagnosed by IgM serology and/or unspecified serology method; D, clinically diagnosed.
# in many cases a combination of diagnostic tests was used to establish the diagnosis. Thus, the number of positive test results exceeds the number of cases.