Sexually Transmitted Infections

Question 1

Sexually transmissible organism

Answer 1

• Virus, Protozoa, insect, arthropod which can be spread by sexual contact (commensal or pathogenic)

Question 2

Sexually transmitted infection (STI)

Answer 2

• Infection by a pathogen which is transmitted through sexual intercourse
• Eg
  
  • Neisseria gonorrhoea
  • HPV type 8

Question 3

Sexually transmitted disease (STD)

Answer 3

• Structure or functional disorder caused by sexually transmitted pathogen
• E.g pelvic inflammatory disease or genital warts

Question 4

Sexually transmitted organisms

Answer 4

• Bacteria
  
  • Chlamydia trachomatis
  • Klebsiella granulomatis
  • Mycoplasma genitalium
• vIRUSES
  
  • HSV
  • HIV
  • HPV
  • Molluscum contagiosa virus
• Parasites
  
  • Pthirus pubis
  • Sarcoptescabei
  • Trichomonas vaginalis

Question 5

Sexually transmissible pathogens not classed as STIs

Answer 5

• COVID
• Ebola
• Zika

Question 6

Characteristics and implications of STIs

Answer 6

• Contagious → contact tracing
• Asymptomatic → prophylactic management
• Unpredictable epidemiology with significant complications → early detection and treatment
• Avoidable → primary prevention is the goal

Question 7

Types of sexual contact

Answer 7

• Group sex
• Anal sex
• Vaginal sex
• Touching genitals
• Mutual masturbation
• ‘Pants on’ cuddling

Question 8

Activity required for transmission

Answer 8

• Group sex → hepatitis C
• Skin contact only
  
  • Pubic lice
  • Scabies
  • Warts
  • Herpes simplex

Question 9

Why are STI’s important

Answer 9

• 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

Question 10

Clinical features of STI’s

Answer 10

• Ulceration
• Lumps
• Genital discharge (penis, vaginal, rectal)
• Non-genital discharge (eyes)
• Rashes
• Systemic symptoms
  
  • Fever
  • Lymphadenopathy
  • Malaise
  • Arthralgia and arthritis

Question 11

Late complications of STIs

Answer 11

• Most of the times extremely rare
• Infertility (chlamydia)
• Cancer (HPV)
• Adverse pregnancy outcomes (syphilis)

Question 12

Why do diagnosis of STIs change over time

Answer 12

1. True change in number of cases
2. Change in diagnosis but no change in number of cases

Question 13

Reproductive number

Answer 13

• 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

Question 14

How is transmissibility reduced

Answer 14

• Vaccination (e.g HPV vaccine)

Question 15

Factors affecting rate of acquiring a new parter

Answer 15

• Increased number of partners
• Increased concurrent partners
• More people having anal sex
• Alcohol
• Social media applications (tinder, Grindr)

Question 16

Factors causing change in number of diagnosis but no change in actual number

Answer 16

• Increased awareness of STI’s = more testing
• Better tests available

Question 17

‘Cores’ and assortative mixing

Answer 17

• 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)

Question 18

Chains and random mixing

Answer 18

• Wider spreading of STIs with an overall lower prevalence
• Infections won’t be sustained as much

Question 18

Chains and random mixing

Answer 18

• Wider spreading of STIs with an overall lower prevalence
• Infections won’t be sustained as much

Question 19

Principles of an STI consultation

Answer 19

• Detailed history
• Partner notification
• HIV testing
• Health promotion

Question 20

STI history

Answer 20

• Presenting complaint
• History of presenting complaint
• Past medical/ social
• Drugs and medications
• Gynae history
• Sexual history
  
  • Assessinghigh risk behaviours
  • Symptoms

Question 21

Sexual history questions

Answer 21

• Last sexual contact
• Casual vs regular partner
• Male vs female
• Nature of sexual acts (if relevant)
• Use of condoms
• Contraceptions used
• Nationality of contact

Question 22

Assessment of longer-term sexual risks in men

Answer 22

• Any sexual contact with another man
• IVDU
• Sexual contact with an IVDU
• Medical care outside UK
• Paid for sex or been paid

Question 23

Principles of partner notification

Answer 23

• Patient tells contacts - ‘client referral’
• NHS tells contacts - ‘ provider referral’

Question 24

Principles of health promotion

Answer 24

• Condoms to prevent transmission of some STIs
• Risk fo oral sex
• Address hazardous drug use (clean needles, brief intervention)
• Vaccination
• HIV pre-exposure prophylaxis