Biological parameters
|
Duration of HIV infection | | (19–22) |
Phase 1 | 6 months | γ1 |
Phase 2 | 6.25 years | γ2 |
Phase 3 | 2 years | γ3 |
Full blown AIDS | 1 year | α |
HIV transmission probability per partnership in a circumcised population | in phase 1, | phase 2, | phase 3 | | (19–28) |
Female to male |
Low to low | 15.00%, | 3.45%, | 7.50% | βnew11,1,1 | βnew21,1,1 | βnew31,1,1 | |
Low to high | 11.50%, | 2.65%, | 5.00% | βnew11,1,2 | βnew21,1,2 | βnew31,1,2 | |
High to low | 0.65%, | 0.15%, | 0.27% | βnew11,2,1 | βnew21,2,1 | βnew31,2,1 | |
High to high | 0.65%, | 0.15%, | 0.27% | βnew11,2,2 | βnew21,2,2 | βnew31,2,2 | |
Male to female |
Low to low | 30.00%, | 6.90%, | 13.00% | βnew12,1,1 | βnew22,1,1 | βnew32,1,1 | |
Low to high | 1.30%, | 0.30%, | 0.54% | βnew12,1,2 | βnew22,1,2 | βnew32,1,2 | |
High to low | 23.00%, | 5.30%, | 10.00% | βnew12,2,1 | βnew22,2,1 | βnew32,2,1 | |
High to high | 1.30%, | 0.30%, | 0.54% | βnew12,2,2 | βnew22,2,2 | βnew32,2,2 | |
Relative risk of HIV if not circumcised | 2 | RRHIV/non-circ | (29–34) |
Proportion of men circumcised | 100% | | (12–14) |
Relative risk of HIV infection if HIV negative or partner is infected with Gc | 3 | RRHIV/Gc | (35, 36) |
First HIV cases (seed) in 1980 | 2 in low activity classes and | X1011(1980)=1, X1021(1980)=1 | (12, 13) |
| 3 in high activity classes | X1012(1980)=2, X1022(1980)=1 |
|
STD modelled
| Gonorrhoea | Gc | (14) |
Duration of infection with Gc | | (14–16, 37, 38) |
Female low | 5.7 months | 1/σ11 | |
Female high (CSW) | 1.3 months | 1/σ12 | |
Male low | 3.3 months | 1/σ21 | |
Male high (frequent clients) | 1.3 months | 1/σ22 | |
Gc transmission probability per partnership | Female to male | Male to female | | (37–41) |
Low to low | 0.60 | 0.95 | ψnew111 | ψnew211 |
Low to high | 0.45 | 0.42 | ψnew112 | ψnew212 |
High to low | 0.22 | 0.8 | ψnew121 | ψnew221 |
High to high | 0.22 | 0.42 | ψnew122 | ψnew222 |
|
Demographic parameters
|
Total population size | 122 605 females and 115 558 males in 1980; 205 380 and 200 003 in 1997 | ∑hs,i Xhski(t) for i=1,2, k=1,2, h=0,4, s=0,1 | (13, 14, 42–44) |
Growth rate of the population | Increases from 2.5% in 1980 to 4.3% in 1997 and eventually plateaus at 3.8% in absence of AIDS | Λki (t) | (14, 16, 42–44) |
Size of the CSW | 1.2% | ∑sX0s12(1980)/ ∑s,i X0s1i(1980), s=0,1, i=1,2 | (13, 17) |
Size of client population | 12.0% | ∑sX0s22(1980)/ ∑s,i X0s2i(1980), s=0,1, i=1,2 | (13, 14, 17) |
Renewal of the CSW | About 2% in 1997 but increases as more CSW get infected and progress to AIDS (details in appendix) | 50% of the CSW who progress to AIDS are replaced by HIV negative with STD status according to Gc prevalence. | (14, 16, 45) |
| R0012(t)=R0s12(t) =0.5•γ3•X123s(t), s=0,1 |
Sexual life expectancy | 45.5 years | 1/μ | (14, 16, 42–44) |
Sexual behaviour
|
Condom use at baseline | 50% of CSW partnerships with men are protected by condoms | Cond1,2,1% (1980) | (14, 16, 17) |
| | | | Cond1,2,2% (1980) |
From T1 = 1980 onward | | Cond2,1,2% (1980) |
| No screening | Cond2,2,2% (1980) | |
Annual rates of new partners acquisition at baseline | | (12, 14, 16–17) |
Low risk females | 1.5 | m11(1980) |
Low risk males | 1.7 | m21(1980) |
CSW | 353 | m12(1980) |
Clients | 37 | m22(1980) |
Mixing pattern | Very assortative | | (14, 16) |
| Female with male | Male with female |
High with low | 5.3% | 4.9% | ρ121(1980) | ρ221(1980) |
High with high | 94.7% | 95.1% | ρ122(1980) | ρ222(1980) |
Low with low | 86.0% | 85.1% | ρ111(1980) | ρ211(1980) |
Low with high | 14.0% | 14.9% | ρ112(1980) | ρ212(1980) |