Sexually Transmitted Infections Flashcards
Sexually transmissible organism
- Virus, Protozoa, insect, arthropod which can be spread by sexual contact (commensal or pathogenic)
Sexually transmitted infection (STI)
- Infection by a pathogen which is transmitted through sexual intercourse
- Eg
- Neisseria gonorrhoea
- HPV type 8
Sexually transmitted disease (STD)
- Structure or functional disorder caused by sexually transmitted pathogen
- E.g pelvic inflammatory disease or genital warts
Sexually transmitted organisms
- Bacteria
- Chlamydia trachomatis
- Klebsiella granulomatis
- Mycoplasma genitalium
- vIRUSES
- HSV
- HIV
- HPV
- Molluscum contagiosa virus
- Parasites
- Pthirus pubis
- Sarcoptescabei
- Trichomonas vaginalis
Sexually transmissible pathogens not classed as STIs
- COVID
- Ebola
- Zika
Characteristics and implications of STIs
- Contagious → contact tracing
- Asymptomatic → prophylactic management
- Unpredictable epidemiology with significant complications → early detection and treatment
- Avoidable → primary prevention is the goal
Types of sexual contact
- Group sex
- Anal sex
- Vaginal sex
- Touching genitals
- Mutual masturbation
- ‘Pants on’ cuddling
Activity required for transmission
- Group sex → hepatitis C
- Skin contact only
- Pubic lice
- Scabies
- Warts
- Herpes simplex
Why are STI’s important
- Significant morbidity and even mortality
- Unpleasant symptoms
- Psychological distress
- Drain on resources
- Managinginfertility
- Cost of HIV medications
- Taking time off work to get medical help
Clinical features of STI’s
- Ulceration
- Lumps
- Genital discharge (penis, vaginal, rectal)
- Non-genital discharge (eyes)
- Rashes
- Systemic symptoms
- Fever
- Lymphadenopathy
- Malaise
- Arthralgia and arthritis
Late complications of STIs
- Most of the times extremely rare
- Infertility (chlamydia)
- Cancer (HPV)
- Adverse pregnancy outcomes (syphilis)
Why do diagnosis of STIs change over time
- True change in number of cases
- Change in diagnosis but no change in number of cases
Reproductive number
- R0 = reproductive number
- B = likelihood of transmission per encounter
- c = rate of acquiring new partners
- D = duration of infectivity
- R > 1 = epidemic sustained
- R < 1 = epidemic reduces
How is transmissibility reduced
- Vaccination (e.g HPV vaccine)
Factors affecting rate of acquiring a new parter
- Increased number of partners
- Increased concurrent partners
- More people having anal sex
- Alcohol
- Social media applications (tinder, Grindr)
Factors causing change in number of diagnosis but no change in actual number
- Increased awareness of STI’s = more testing
- Better tests available
‘Cores’ and assortative mixing
- Some prefer to have sex with people like them (ethnicity, background)
- Causes high prevalence within subpopulation
- Syphilis (people who exchange sex for drugs)
- HIV (men who have sex with men)
Chains and random mixing
- Wider spreading of STIs with an overall lower prevalence
- Infections won’t be sustained as much
Chains and random mixing
- Wider spreading of STIs with an overall lower prevalence
- Infections won’t be sustained as much
Principles of an STI consultation
- Detailed history
- Partner notification
- HIV testing
- Health promotion
STI history
- Presenting complaint
- History of presenting complaint
- Past medical/ social
- Drugs and medications
- Gynae history
- Sexual history
- Assessinghigh risk behaviours
- Symptoms
Sexual history questions
- Last sexual contact
- Casual vs regular partner
- Male vs female
- Nature of sexual acts (if relevant)
- Use of condoms
- Contraceptions used
- Nationality of contact
Assessment of longer-term sexual risks in men
- Any sexual contact with another man
- IVDU
- Sexual contact with an IVDU
- Medical care outside UK
- Paid for sex or been paid
Principles of partner notification
- Patient tells contacts - ‘client referral’
- NHS tells contacts - ‘ provider referral’
Principles of health promotion
- Condoms to prevent transmission of some STIs
- Risk fo oral sex
- Address hazardous drug use (clean needles, brief intervention)
- Vaccination
- HIV pre-exposure prophylaxis
