202. Reproductive Impact of STIs

Question 1

Between the following bugs, order from highest to lowest incidence:
Chlamydia, HBV, HIV, HPV, HSV, Syphilis

What demographics are Chlamydia more common in?
How are trends changing?

Answer 1

HPV (trending down with vaccine) > Chlamydia (more asx pts) > HSV > HIV (first year it went down) > HBV > Syphilis

More common in W > M (more often silent asx in W)
Higher incidence in blacks (barriers to tx/prevention)
higher incidence in MSM: account for 75% all 1o and 2o syphilis cases (stigma, anal risks, access to care)
GROWING trend in congenital syphilis (due to MSM)

Question 2

How can you quantify the rate of acquisition/spread of STI?

What factors impact the variables of this equation?

Answer 2

Rate of Spread = BCD

C: RATE of partner change

• total # partners, sexual concurrency (# at once)
• prevalence of STD w/in sexual network

B: EFFICIENCY of transmission

• Gonorrhoea > Chlamydia > Chancroid > HBV > HIV
• pathogen factors: phenotype (asx/sx), genotype (pili)
• host factors: Age (younger = more exposed cervix), Women/MSM (higher mucosal surface area), Race/Ethnicity (disparity in dx, tx, prevention), Genotype (CCR5 mutation: homozygous less infection, heterozygous less progression)
• vector: anal intercourse highest risk (highest pathogen load - semen; highest surface area - rectum; highest conc target cells - monocytes/macrophages in subepithelium)
• environment: higher risk with trauma/IPV, less condom wearing, lower risk with alcohol taxes, higher risk with lower SES

D: duration of infectiousness
- Chlamydia: shortest duration of shedding in infected but untreated person

Question 3

What are the differences between old and new STI prevention efforts

Answer 3

Old: target behavior change, not successful (abstinence, condoms, partner limits)

New: modify host/enviro factors

• microbiocides: decrease exposure (layer protects macrophages)
• Pre-Exposure Prophylaxis (PreP): for HIV - ppl to reduce HIV acquisition
• MOST IMPORTANT ADVANCEMENT: dx and tx infected ppl = less TRANSMISSION
• male circumcision = less risk of acquiring HIV (less langhans cells)
• Will not eliminate health disparities until SDoH addressed

Question 4

What is the most important factor in perinatal HIV transmission? How do you prevent this?

Answer 4

Maternal HIV viral load most important determinant
Prevention: dx and tx! - HAART highly effective in reducing transmission (and C-section plays role in women with high viral loads)