Diagnosing Infectious Disease
By Levi Clancy for Student Reader on
updated
Assays to diagnose infectious disease must be: specific (no false positives or cross reactivity); and sensitive (able to identify even a single cell). Indirect assays detect antibodies, which are evidence of past and perhaps prsent infection. Direct assays detect the parasite itself.
Technique | Direct? | Overview |
---|---|---|
Xenodiangosis | Direct | |
Indirect | ||
DNA Assay | Direct | PCR detection of any microbe has two criteria: specificity to detect only the microbe in question; and sensitivity to detect the microbe at low abundance. |
Microscopy | Direct | Diagnostic microscopy is usually performed on blood smears or following culture in synthetic media. Centrifugation can be performed to concentrate scarce parasites into a white cell layer called the buffycoat. |