Aetiology of STIs

Question 1

Pharyngeal gonorrhoea usually?

Answer 1

asymptomatic

Question 2

Ro>1 means?

Answer 2

infection/prevalence is spreading as infected only contacts non-infected
levelling of epidemic: infected with infected

Question 3

Ro<1 means?

Answer 3

infection is waning/decreasing

Question 4

Ro = STI transmission equation?

Answer 4

Ro = BcD
B = transmission probability
c= rate of partner change
D= duration of infection

Question 5

best way to reduce Ro for HIV with Ro = BcD?

Answer 5

decrease probability of transmission= B

Question 6

Ro = BcD for gonorrhoea how to decrease Ro?

Answer 6

if you can halve the duration of infectiousness, could drop Ro below 1 ie. heterosexuals with gonorrhoea

Question 7

Ro = BcD, the c is rate of partner change made up of 2 things:

Answer 7

Non-core (mean)

core (SD)

Question 8

what is assortative mixing?

Answer 8

high partners with high partners

Question 9

what is disassortative mixing?

Answer 9

high partners with low partners

Question 10

Concurrency of partners?

Answer 10

partner overlap, vs. serial monogamy

Question 11

accounting for core group in Ro = BcD?

Answer 11

square the SD of ‘c’ = rate of partner change

Question 12

Is assortative or disassortative worse?

Answer 12

assortative (high risk with high risk), core with core

Question 13

fear campaigns don’t work overall: why?

Answer 13

doesn’t target core group: encouraged assortative mixing in the core group: altered mean, not SD

Question 14

sex workers and STIs?

Answer 14

Very low. 100% condom use.

Most likely to get STI from non-paying partners

Question 15

HPV vaccine doing what to genital warts?

Answer 15

Ro<1 due to 70% coverage of young women

Question 16

what part of Ro = BcD determine prevalence of STI?

Answer 16

Duration dominates