Dan - STIs Flashcards
R0 in regards to STIs
R0 (basic reproduction number) = B (transmission coefficient (efficiency)) * C (mean rate of partner change) * D (mean duration of infectiousness)
Define R0
Number of secondary cases caused by a single case of infection in a population that is totally susceptible with no interventions
Reducing transmission coefficient in STIs
eg Condoms
Reduce mean rate of partner change in STIS
(ie reducing R0 in STI spread)
Education
Reduce mean duration of infectiousness in STIs
Screening and early treatment
Asymptomatic screening
Syphilis vs HSV
Syphilis tends to be painless lesion
Treatment Chacroid
Ceftriaxone IM stat
Azithromycin PO stat
Cipro PO 3/7 or Eryhthromycin PO 7/7
Cannot use cipro if preg/breastfeeding
3 most important causes of genital ulcers
HSV - self limiting, vesicles
Syphilis - usually painless solitary
Chancroid - often painful +/- lymphadenopathy (less common since 1990)
What is syndromic management?
Use of treatment algorithms wi cure common causes of defined clinical syndromes
Advantages of syndromic management
Do not need specialist tests
Treat at first appt
Can potentially reduce mean rate of infectiousness
Quicker symptom relief
Cheap
Disadvantages of syndromic management
Risk of over treatment - drug resistance (using multiple drugs to cover multiple organisms)
Only symptomatic treated - women likely disproportionately disadvantaged
Issues with partner notification
Organism causing chancroid
Haemophilus ducreyi
Gram-negative coccobacilli bacteria
Cause of syphilis
Treponema pallidum
Stages of syphilis
Primary - local - chancre
Secondary - dissemnation, systemic illness
Latent period
Later/tertiary - skin/neuro/cardiac
Diagnosis Syphlis
Non treponemal test (RPR VDRL) - active disease/screening (False +ve SLE, Liver disease, HIV, leprosy)
Treponemal test - TPHRA/TPPA/FTA - exposure (positive for life)
Generally use combination of the two - RDT with both available
