Modelling HIV Intervention among Most-at-Risk/Key Population: Case study of FWSS in Nigeria

Using FWSS in Nigeria as a case study, this research develops a novel risk equation for estimating new infections among FWSS, their clients and communities. It uses a hybrid SUDT and SIT structural model. It considers number of contacts, number of protected and unprotected sexual acts, population and other existing values as base inputs. Simulation of the model was done using python programming. The model also estimates the impacts of these interventions on the clients of the sex workers, their female partners and the general population. The levels of the program implementation, needed on each scenario, to achieve the required number of averted new infections are also modelled. This model can be used to estimate the risk of a population set to a sexually transmitted disease. Public health workers can use the model to prepare a fit forpurpose intervention program for specific community members. Citation: Akwafuo S, Shattock A, Mikler AR (2017) Modelling HIV Intervention among Most-at-Risk/Key Population: Case Study of FWSS in Nigeria. J AIDS Clin Res 8: 732. doi: 10.4172/2155-6113.1000732

Using FWSS in Nigeria as a case study, this research develops a novel risk equation for estimating new infections among FWSS, their clients and communities. It uses a hybrid SUDT and SIT structural model. It considers number of contacts, number of protected and unprotected sexual acts, population and other existing values as base inputs. Simulation of the model was done using python programming. The model also estimates the impacts of these interventions on the clients of the sex workers, their female partners and the general population. The levels of the programme implementation, needed on each scenario, to achieve the required number of averted new infections are also modelled. This model can be used to estimate the risk of a population set to a sexually transmitted disease. Public health workers can use the model to prepare a fit-for-purpose intervention program for specific community members.

Objective
The objective of this research is to develop a mathematical model to estimate how many indirect HIV infections will be averted among FWSS, their clients and the general population, attributable to prevention programs targeting female sex works in Nigeria. The model also estimates the impacts of these interventions on the clients of the sex workers, their female partners and the general population. The model includes a risk ratio used to estimate the impact of the programme on each of the sub-population sets. The number of new infections averted on the sex workers and their clients, attributable to different scenarios and levels of the programme implementation is presented in this paper.

Assumptions
• Net rate of migration from SFWSS group to SGF is the same as SGF>>SFWSS, (go/ho), UFSW and different from IGF to DFSW and TFSW

Clients of female sex workers
Other sexual partners of the clients of female sex workers

Rate of migration (Gen Male)
Rate of migration from GM to Clients g2 1

Rate of migration (Gen Male)
Rate of migration from Clients to GM h2 1

Rate of migration (Gen Male)
Rate of migration from GM to Clients g2 1

Rate of migration (Gen Male)
Rate of migration from Clients to GM h2 1

Risk equation for FSW
[ C * I / N * ) It was observed that if the status quo (37% of eligible positive FSW on treatment) is maintained, the new infection rate will gradually increase by 3.6% in five years' time. Putting 80% of eligible positive FSWs on treatment will avert 2789 new infections in the same duration and reduce the current rate of new infections to 0.7. A slight decrease of 0.3% would be experienced in the general female population. Putting all FSWs on treatment returns a 89.7% reduction on the number of new infections among clients of FSW.

Conclusion and Recommendations
The simulation model reveals the efficiency of treatment in reducing the rate of new infections among FSWs, their clients and general female. The models reveal the importance of the investing in the FSW intervention programs now, rather in the future. The model outputs can be used to calculate the Quality Adjusted Life Years (QALY) to be gained during the intervention. A slight contribution of the total number of condom distributed to a reduction in new infection rate was also noticed. Further modelling scenarios are required to effectively infer on the efficiency of the intervention programs.