1. CHAIN OF INFECTION
STI POINT OF VIEW

2. Chain of Infection Vector – infected person
Pathogen – Bacteria or Virus
Reservoir – where “it lives”
Portal of Exit –
Mode of Transmission
Portal of Entry
Susceptible Host

3. Vector: Person with STI
Considerations
Behavior of the person
Precautions
Number of partners
Stage of infection
Active
Latent

4. Reservoir Virus Bacteria Mucous Membranes Infected Secretions Skin
HPV lives in skin cells
Nerve Endings
Herpes Simplex 2 lives in nerve endings
Blood
HIV
Hepatitis B
(greater concentrations, more infectious than HIV)
Semen – HIV, HBV
Vaginal fluids -- ditto
Cervical fluids -- ditto
Mucous Membranes
Throat
Vagina
Urethral opening of Penis
Anus/Rectum
Infected Secretions
Vaginal fluids
Cervical Fluids
Semen
Pre-ejaculate

5. Infectious Agent Virus Bacteria Chlamydia Gonorrhea HIV
Herpes Type 2 (genital)
Human Papilloma Virus
Hepatitis B Virus
Bacteria
Chlamydia
Gonorrhea

6. Portal of Exit Virus Bacteria Through shedding of infected skin cells
Herpes
HPV
Released in body fluids
HIV
HBV
Contact with other mucous membrane
Gonorrhea
Chlamydia
Syphilis

7. Mode of Transmission Virus Bacteria Intercourse – Anal and Vaginal
Receptive partner
HIV
HBV
Frottage – Rubbing
HPV
Herpes
Oral sex
Gonorrhea
Chlamydia
Put in throat by penis
Intercourse – Anal and Vaginal
Either partner
Infected mucous membranes rub

8. Portal of Entry Virus Bacteria See portal of exit
Immune cells at top levels of mucous membranes
HIV
Wall of colon or rectum and micro-tears
Mucous Membrane of vagina
Cervix
See portal of exit

9. Susceptible Host Viral Bacteria Uninfected Person Uninfected Person
No Immunity
From having the infection before
From getting the antibodies from another person
From vaccination
Immune system stressed
Not taking preventive drugs
HIV –
Pre Exposure Prophylaxis
Social and sexual networks
Uninfected Person
Never infected before
Infected before but treated and cured
Can get infected again
and again
and again…

11. Breaking the chain

12. Vector Control Behavior Modification Social Support
Address Social Determinants – Quality of Life
Medical Treatment
Patient Education

13. Reservoir Virus Bacteria Dry up the reservoir by using
Anti-Viral Drugs
Reduce viral activity
Less infectious
Drain the reservoir
Antibiotics will rid of infection

14. Portal of Exit Virus Bacteria Condoms!
Anti-Microbials (under investigation)
Microbicides link
Condoms!
Anti-Microbials -- ??
NOT spermcides…

15. Mode of Transmission Virus Bacteria Intercourse – Anal and Vaginal
OUTERcourse!!!
Receptive partner
HIV
HBV
Frottage – Rubbing
HPV
Herpes
ABSTAIN during outbreak
ABSTAIN until symptoms are cleared
Condoms!
OUTERcourse!!!

16. Portal of Entry
Virus
Bacteria
Condoms!
Condoms!

17. Susceptible Host Viral Bacteria Get Tested
Get Vaccinated!
Hepatitis B
HPV
Prevention for High Risk
Anti-Viral PrEP (HIV)
Pre
Exposure
Prophylaxis
Truvada
Work with specialist
Monthly check ups
Work toward risk reduction
Get Tested
Women under 25 who have sex (yearly for Chlamydia)
MSM – every six months to one year
Every 3 months for syphilis in bigger cities.
Get Told (you’ve been exposed)