CHAIN OF INFECTION STI POINT OF VIEW

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

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

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

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

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

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

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

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…

Breaking the chain

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

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

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

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!!!

Portal of Entry Virus Bacteria Condoms! Condoms!

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)