Infectious Disease Sensitivity and Specificity

Most clinical tests use sensitivity and specificity as measures of performance and accuracy. “Sensitivity” describes how accurate the test is at identifying positive results correctly, and “specificity” describes how accurate the test is at identifying negative results correctly.

See the chart below for our laboratory’s sensitivities and specificities for each test.

Assay Sensitivity Specificity
HIV 100% 100%
HBV 100% 100%
HCV 96.90% 99.10%
Syphilis (EIA) 100% 100%
HSV2 96.30% 98.40%
HPV 100% 100%
CT 100% 100%
NG 100% 100%
TV 100% 100%

Due to chemical and physical limitations, even the best test is not always 100% accurate, which is why we recommend confirmatory testing with a different method for any positive result, or if an unexpected negative result is obtained. Any positive result should immediately be taken to your primary care provider (or a local state health department) for further analysis and treatment options. A false negative result is also possible if testing is performed too early after exposure, or within what is called the “window period.” It takes time for the body to develop detectable levels of antibodies after exposure to an infection. For example, the window period for HIV and Hepatitis C infection can be as long as 8 to 12 weeks. That is why we recommend that testing be repeated after about 2 months of obtaining a negative result following a high risk exposure.

Many of the individual components of our tests are FDA cleared and all tests have been fully validated according to state and federal guidelines (which include CLIA and College of American Pathologists (CAP) standards). Our laboratory only uses the most current methods that are proven to have the highest level of accuracy for clinical diagnostic testing.

A summary of the testing methods is listed below:

Dried Blood Serology

  • Human Immunodeficiency Virus (HIV)
    • Results are obtained using a Combo Antigen/Antibody ELISA for the qualitative detection of HIV p24 antigen and antibodies to HIV type 1 (HIV-1 groups M and O) and HIV type 2 (HIV-2) in human blood.
    • Sensitivity: 100%
    • Specificity: 100%
  • Hepatitis B Virus (HBV)
    • This test uses an ELISA test system for the qualitative detection of HBV surface antigen in human blood.
    • Sensitivity: 100%
    • Specificity: 100%
  • Hepatitis C Virus (HCV)
    • This test uses an ELISA test system for the qualitative detection of antibodies to hepatitis C virus (anti-HCV) in human blood.
    • Sensitivity: 96.90%
    • Specificity: 99.10%
  • Syphilis EIA
    • Syphilis is a disease caused by infection with the spirochete Treponema pallidum (T. pallidum). We use an ELISA assay for the qualitative detection of IgG antibodies to T. pallidum. Since our assay specifically targets antibodies against the organism, patients with previously treated syphilis will still be positive on this test. A positive result may indicate recent, past, or successfully treated syphilis infections, therefore, the test cannot be used to differentiate between active and past cured cases.
    • Sensitivity: 100%
    • Specificity: 100%
  • Herpes Simplex Virus, type II (HSV2)
    • This test uses an ELISA IgG test to detect antibodies produced after exposure to the virus. It is intended for qualitatively detecting the presence or absence of human IgG class antibodies to HSV-2 in human blood.
    • Sensitivity: 96.30%
    • Specificity: 98.40%

Genital Collection

  • Human Papilloma Virus (HPV)
    • This test utilizes amplification of target DNA by polymerase chain reaction and nucleic acid hybridization for the detection of 14 high-risk HPV types in a single analysis. The test specifically identifies types HPV16 & 18 while concurrently detecting the rest of the high-risk types: 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68.
    • Sensitivity: 100%
    • Specificity: 100%
  • Chlamydia trachomatis (CT)
    • This test uses Strand Displacement Amplification technology for the direct, qualitative detection of Chlamydia trachomatis in vaginal swab specimens and male urine specimens, as well as oral and anal samples.
    • Sensitivity: 100%
    • Specificity: 100%
    • The lower limit of detection for chlamydia is 450 copies/mL.
  • Neisseria gonorrhoeae (NG)
    • This test uses Strand Displacement Amplification technology for the direct, qualitative detection of Neisseria gonorrhoeae in vaginal swab specimens and male urine specimens, as well as oral and anal samples.
    • Sensitivity: 100%
    • Specificity: 100%
    • The lower limit of detection for gonorrhea is 20 copies/mL.
  • Trichomonas vaginalis (TV)
    • This test uses Strand Displacement Amplification technology for the direct, qualitative detection of Trichomonas vaginalis DNA in vaginal swab specimens.
    • Sensitivity: 100%
    • Specificity: 100%
    • The lower limit of detection for trichomoniasis is 40 copies/mL.

In rare cases you may receive a result of “Indeterminate.” This may be due to testing for the infection too early or if there are other antibodies causing interference. It is recommended that a repeat test be taken or a different type of test be performed through your physician’s office.

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