Table 1

 Model input parameters used to obtain the baseline Cotonou model fits

Types of model inputDefinition of model inputModel inputs for: MaleFemale*Reference for model input value
*If one model input is shown then this is valid for males and females. All parameters with a range associated with it were varied in the uncertainty analysis used to obtain model fits.
†The parameters associated with the POC test were not varied to obtain the initial model fits.
EpidemiologicalAverage duration of Ng/Ct (months)6–18Refs 46–48. Also depends on level of STI treatment
Average duration of ulcerative STI (months)2–12
Average duration between HIV and AIDS (months)84Refs 49–51
Percentage of males circumcised99%Ref 19
Transmission probabilitiesProbability of HIV transmission per sex act: Male to female:0.001–0.003Refs 30, 31, 52
Female to male:0.0006–0.0014
Percentage decrease in female to male HIV transmission probability if circumcised0–58%Ref 53
Probability of STI transmission per sex act: Ng/Ct:0.10–0.53Refs 32–34, 54–57
Ulcerative STI:0.1–0.5
Average Ng/Ct co-factor per sex act2–8Refs 4, 58
Average ulcerative STI co-factor per sex act3–13
Sexual transmission multiplicative co-factor during high viraemia phase (for 1.5 months)10–20Refs 59–61
Condom efficacy per sex act80–95%Refs 62, 63
Population size and demographic inputsInitial size of sexually active population310,000
Life expectancy in years51Ref 64
Average number of years live in the area40Ref 65
Fixed sexual behaviourAverage frequency of partner change: Main sexual partners per 6 months0.01–0.100.01–0.05Refs 20, 23. No data for casual partners of females in Cotonou, so assumed to be same as males
Casual sexual partners per 6 months1.6–2.2
Average frequency of sex acts in: main partnerships (per month)4–12Few data for Cotonou, so inputs given ranges similar to other African settings40
Casual partnerships (per month)2–5
Sex worker sexual behaviourAverage monthly frequency of clients per FSW52 (28–104)Refs 16, 21
Average duration of sex work in months24–72Current FSWs have been sex workers for about 2 years16
Distribution of sexual activityPopulation distribution with respect to level of sexual activityNo partners20%14%Refs 20–23, 65
Just main partner49–55%84%
Main and casual partner2–12%0.8%
Client of FSW and FSW13–29%1.2%
Condom useAverage consistency of condom use: main partnerships per sex act5–15%Refs 16, 20, 23
FSWs with their clients last sex act:Not reached60%Ref 16
Distribution of condom use of males and females with their casual partnerships.None44–54%40–80%Refs 20, 23, 65, 66
STI treatment of FSWs at SIDA-2 clinicCoverage of STI screening among FSW12–15%200–250 SWs reached every month16 (250/1900 = 13.2% per month)
Sensitivity of modified syndromic management (SM) or POC testNg/Ct48% (SM), 50–80% (POC)†Ref 8. Assume treat all GUD but those caused by HSV-2 are not cured
Specificity of modified syndromic management (SM) or POC testNg/Ct75% (SM), 95% (POC)*
Effectiveness of treatment regimenNg/Ct95%Most STI cases treated effectively except those due to HSV-2.16
Cost of POC test for Ng/Ct (2004 $US)1–4†No test currently available
STI treatment at public and private clinicsPercentage of STI cases that never have symptoms10–35%10–35%81% of clients with Ng/Ct and TV were asymptomatic.28 Health dimensions of sex and reproduction.67
Percentage of males and females with symptoms that attend the clinic per month46–51% (39% to private clinic)46% of males sought health services if had STI.29 When clients had STI, 12% went to public clinic and 39% to private clinic.28 Few data on females so assumed same as males
Percentage of individuals with STI symptoms at clinic that don’t have an STI50–80%40–80%Greater than 47% of men and 36% of women with symptoms had no STI at health clinic7
Sensitivity of syndromic algorithmNg/Ct92%87%For individuals with Ng/Ct symptoms at public health.7 Assume all cases of GUD are treated.
Specificity of syndromic algorithmNg/Ct60.3%42%
Effectiveness of treatment regimenNg/Ct50–90%Michel Alary personal communication: 90-95% of STDs treated correctly in SIDA-2 supported clinics and 50% otherwise. HSV-2 not curable