CLS 1113 Introduction to Clinical Laboratory Practices

1. CLS 1113Introduction to Clinical Laboratory Practices Unit 7 Serological Diagnosis of Infectious Diseases

2. Syphilis • Treponema pallidum (Spirochete) • Helically coiled - “Cork-screw” motility • Have no natural reservoir in the environment • Must multiply within a living host • Difficult to isolate in the laboratory • Transmission: sexual or congenital • >50,000 cases per year per your textbook • http://www.cdc.gov/nchstp/dstd/Fact_Sheets/Syphilis_Facts.htm

4. Spirochete Image

5. Syphilis • T. pallidum • rapidly destroyed by heat, cold, and drying out. • Sexual transmission • 1/3 of individuals

6. Syphilis - Staging • Primary Stage • Initial lesion - chancre, develops from 10 – 90 days post infection. The lesion is painless. • The lesions usually occur on the external genitalia, can also appear on the cervix, vagina, inside the mouth and the rectum.

7. Syphilis • Secondary Stage • If untreated, ¼ of cases will progress to the secondary stage. • The is characterized by the systemic dissemination of the organism. • Lymphadenopathy, malaise, fever, pharyngitis, skin rash, etc. • Skin lesions will last up to 8 weeks, but relapses can occur up to 4 years

8. Syphilis • Latent Stage • Patients are non-infectious • Patients lack clinical symptoms • Occurs around 1 year post-infection

9. Syphilis • Tertiary Stage • Usually occurs 10-30 years after the secondary stage • Patients exhibit neurological, cardiac and cutaneous involvement • Large skin lesions • Degeneration of the spinal cord • Mimics meningitis • Destruction of elastic tissue of the Aorta

10. Congenital Syphilis • Syphilis passes from mother to child • Can occur starting at 18 weeks gestation • 2800 cases in 1990 • http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5027a1.htm • 40% mortality rate • Bone, neural, and cutaneous abnormalities

11. Immune Response • Primary Defense • Intact skin and mucous membranes • What is the primary defense against STD? • Secondary Defense • T cells, macrophages, and antibody production

12. Testing • Direct detection • Darkfield microscopy • Fluorescent Antibody Testing

13. Testing • Non-Treponemal Serological Tests • Rapid Plasma Reagin (RPR) and Venereal Disease Research Laboratory (VDRL) Tests • Tests detect the presence of “reagin”, an antibody against cardiolipin (lipid molecule). • Reagin antibodies • IgG or IgM • Also found in other diseases • RPR-Antigen Suspension containing charcoal particles