Epidemiology of STIs Flashcards
What are the symptoms of primary HIV infections?
Sore throat
Fever
Rash
Pharyngitis
What is the rate of HIV in the men who have sex with men community in Melbourne?
1 in 10
What is disassortative mixing?
The mixing between high risk groups and low risk groups (core with non-core)
eg Married men who have sex with men
In which group of people does circumcision reduce transmission of HIV?
In those performing insertative anal sex
Is pharyngeal gonorrhoea usually symptomatic or asymptomatic?
Asymptomatic
What determines ß (the probability of transmission per partnership)?
Condon use
Types of sex and duration
Cofactors eg coinfections, bleeding HIV
What is the definition of basic reproductive rate?
The number of seconday cases of an infection that arise from a primary case at t=0
What is PreP?
Pre-exposure prophylaxis for HIV
What is concurrency of partners?
When one or more partners in a relationship have other sexual partners while continuing sexual activity with the original partner
What occurs at the steady state of an epidemic?
New cases=cured cases
What are some strategies for reducing the probability of transmission of HIV?
Reduce cofactors
Reduce viral load
Increase condom use
Change type of sex
What an epidemic to occur, what must the basic reproductive rate be?
>1
Which is worst for transmission; assortative (high risk with high risk) or disassortative (low risk with high risk)
Assortative
When PreP indicated?
When a long term partner is HIV+
What is the average duration of infection of people infected with gonorrhoea in urban areas?
A few days
By what margin does post exposure prophylaxis reduce the transmission of HIV?
70-80%
Which are easier to control, bacterial or viral STIs?
Bacterial
Why is the rate of syphilis diagnosis increasing in the recent past?
Less condom usage
More unsafe sex
More partners
What is the difference between basic and effective reproductive rate?
In the effective reproductive rate R0 is multiplied by the proportion susceptible
How does circumcision reduce the transmission of HIV?
The skin on the glands becomes tougher in the absence of a foreskin > more immune to HIV
What is the equation for basic reproductive rate?
R0=BcD
Beta = Transmission probability per sexual partnership
c = Rate of partner change
D = Duration of infection
What is the core group in STI transmission?
A small group of people that have many partners and are the core transmitter of the infection
What must all interventions to reduce STIs do?
Target the core group to reduce the standard deviation