Table 1.
Summary of methods for Q fever diagnosis
| Method | Advantages | Limitations |
|---|---|---|
| Indirect Detection Methods | ||
| Indirect Immunofluorescence Assay (IFA) | specific, sensitive, economical | subjective, inter-assay and inter-laboratory variability, convalescent sample needed for confirmation |
| Complement Fixation Test (CFT) | specific, economical | time-consuming, labor intensive, lacks sensitivity, convalescent sample needed for confirmation |
| Enzyme-linked immunosorbant assay (ELISA) | sensitive, high throughput | difficult to interpret results, inferior to IFA in follow-up serum |
| Western blot (WB) | ability to differentiate reactive antigens | time-consuming, labor intensive, not suitable for large sample sizes |
| Enzyme-linked immunospot (ELISPOT) | reduced inter-assay and inter-laboratory variability relative to IFA | time-consuming, requires fresh (<12 h) samples |
| Direct Detection Methods | ||
| PCR (conventional, nested, real-time) | broad specimen range, specific, sensitive, economical | requires specialized equipment, sensitivity declines after first week of symptom onset, possibility of false negatives |
| Loop-mediated isothermal amplification (LAMP) | eliminates need for specialized equipment, sensitive, rapid | limited use in clinical setting |
| Silicon microring resonator | label-free, rapid | requires specialized equipment, limited use in clinical setting |
| Next-generation sequencing (NGS) | screen for multiple pathogens simultaneously, multiplex targets, detect novel species/variants | requires specialized equipment, time-consuming, labor intensive, sensitivity declines after first week of symptoms |
| Immunohistochemistry (IHC) | rapid direct detection without the risk of working with viable organism | requires specialized equipment, difficult to quantify, requires biopsy |
| Fluorescence in situ hybridization (FISH) | more sensitive than IHC | requires specialized equipment, difficult to quantify |
| Culture | direct pathogen detection, allows for cultivation/characterization of isolates | hazardous, time-consuming, restricted to select facilities, may need to confirm by PCR/other method |