Lecture 29 - Epidemiology of STIs Flashcards
What are the local clinical syndromes due to STIs?
- Genital lesions (ulcers, warts)
- Urethritis, vaginitis, cervicitis
- Proctitis (rectal infection)
- Pharyngitis (throat infection)
- Pelvic inflammatory disease (PID)
What are the systemic clinical syndromes due to STIs?
HIV–AIDS
• Primary HIV infection
• Immunodeficiency & complications (“opportunistic” infections & malignancies)
Syphilis
• Primary (genital ulcer “chancre”)
• 2o (skin), 3o (brain, spinal cord, blood vessels) • Congenital syphilis infection
What are the ways we can diagnose STIs?
- swabs
- microscopy
- culture
- antigen detection assay
- PCR
What is an ideal treatment for an STI?
- on the spot
- single dose
- no side effects
- cheap
- effective prevents
- efficient partner treatment
What is the reality of treatment that we have to face?
- asymptomatic infection
- multiple infections
- long course treatment needed
- antibiotic resistance
- latency, reactivation
- partners unknown
- no prevention
How do we measure the spread of infection?
Reprouctive rate - Ro
Average number of secondary cases produced by one primary case
What happens when Ro > 1?
Epidemic
• spread of the disease to many people
What happens when Ro = 1?
Endemic
What happens when Ro < 1?
Disease eventually disappears
What are the determinants of Ro?
Ro = B x c x d
B: transmissability
c: n° of contacts
d: duration of infectivity
Largely dependent on rate of different sexual partners
Why do we want to reduce transmission of disease?
Less people potentially infected
How do we reduce transmissability?
- condoms
* reduction of other STIs
How do we reduce duration of infectivity?
• treatment
How can we reduce the n° of contacts?
- core group interventions
* community-wide behavioural change
What are the different groups in society?
- general population
- bridging population
- core transmitters
How do we manage STIs in Australia?
• Public awareness • Health services: - GPs - Rural - Sexual health cilics • Partner tracing and treatment • Screening • Vaccination (i.e. HPV) • Surveillance • Promotion of safe sex
Why is screening important for management of STIs?
People need to know that they are infected so that they don’t spread it to others
Describe promotion of safe sex
- education in schools
* facilitation
Describe surveillance of STIs
• Diagnosis:
- State health departments etc.
• Antimicrobial resistance
Describe the difficulties faced in the Indigenous populations
• Higher rates of STIs
- chlamydia
- gonorrhoea
- syphilis
- Donovanosis (Klebsiella)
• Treatment obstacles
- limited care access
- difficult partner tracing
Compare Gonorrhoea in Indigenous populations and in Melbourne
Rural populations: gonorrhoea is penicillin sensitive
Melbourne: resistance: beta-lactamase producers
Describe the trends in chlamydia infection
10% increase per year in Victoria
Which age groups are most at risk of Chlamyia infection?
Males: 20-29
Females: 15-19
Describe the Chlamydia iceberg
Tip of the iceberg:
• 2500 cases that we see
Underwater:
• tests
• thousands of cases that are being missed
What are the control strategies of Chlamydia?
- Surveillance
- Targeted screening of high risk groups
- Education
- Increased community awareness
- Partner notification processes
Describe Partner notification processes
• ‘Let them know’
• Trackers
- don’t necessarily know who the person is
• Direct discussion with partner
Describe the trends in Gonococcal infections
late 1980s: noted rise in ‘men who have sex with men’
• after HIV treatment, there was a complacency, and a subsequent increase in rates
Which groups are most affected by Gonorrhoea?
Males 20-24 yo
Describe the trends in Syphilis
2000-2007: increase in incidence
2007-2011: declining due to campaigns
Describe the trends in HIV
Late 80’s: rapidly increase
80’s -2000: decreased
2000’s stabilised
Which communities are affected by HIV?
Africa: heterosexual population
Australia: men who have sex with men
What are the HIV control strategies in Australia??
• testing • surveillance • treatment • Health promotion - across many different groups
