Question

Gonorrhea and chlamydia

-Why aren't there serological tests for gonorrhea or chlamydia that could be used for screening purposes?

-Why is it unlikely that there will be vaccines available for either of these diseases in the near future?

Answer 1

Sexually transmitted disease one of the major impact is that once infected , chances of repeated infection and the person can infect others without symptoms. Serological tests for gonnorhea cannot be used for screening tests as they are high resistant strains, their antigenic variationas it get diversified based on different surface and evade immune system. As the starins have low sensitivity and specificity it may vary in patients based on sex, duration of infection, symptoms, time required for immunological response and crooss reactivity with other antigens. In case of Chlamydia anitbodies  are not useful to detect epithelial infection , detection require longer interval of time, and unable to differentiate antibody.They have two developmental nature.They evade the persons body without symptoms and replicate inside the body and replicated bacteria of triple size can also cause disese and assymptomatic persons can transfer the disease to others.

Vaccines are still under research for these STDs and found difficulty in developing vaccinnes as themajor impact of these strains are  variation in the expression and specificity of surface antigens and their defense mechanism such as multiple mechanism for resisting the complement system.Chlamydias complex life style in host as replicated and non replicated form make it difficult to develop vaccines.