“…The best results were, however, obtained by all the IDA-based regimens evaluated, with achievement of parasite elimination facilitated in all countries by the year 2023. Although contingent on the pattern of MDA roll-outs, these results clearly support increasing suggestions for countries to switch to these more intensive drug regimens, where feasible, to accelerate their prospects for meeting the goal of LF elimination as rapidly as possible [66].…”
“…The best results were, however, obtained by all the IDA-based regimens evaluated, with achievement of parasite elimination facilitated in all countries by the year 2023. Although contingent on the pattern of MDA roll-outs, these results clearly support increasing suggestions for countries to switch to these more intensive drug regimens, where feasible, to accelerate their prospects for meeting the goal of LF elimination as rapidly as possible [66].…”
“…(30) we may thus use the solution to the mean field Eqs. (10) and (12) to stochastically evolve trajectories of the mean worm burden with temporal correlations.…”
Section: A Mean Field Expansion Of the Systemmentioning
Predicting the effect of different programmes designed to control both the morbidity induced by helminth infections and parasite transmission is greatly facilitated by the use of mathematical models of transmission and control impact. In such models, it is essential to account for as many sources of uncertainty-natural, or otherwise -to ensure robustness in prediction and to accurately depict variation around an expected outcome. In this paper, we investigate how well the standard deterministic models match the predictions made using individual-based stochastic simulations. We also explore how well concepts which derive from deterministic models, such as 'breakpoints' in transmission, apply in the stochastic world. Employing an individual based stochastic model framework we also investigate how transmission and control are affected by the migration of infected people into a defined community. To give our study focus we consider the control of soil-transmitted helminths (STH) by mass drug administration (MDA), though our methodology is readily applicable to the other helminth species such as the schistosome parasites and the filarial worms. We show it is possible to define a 'stochastic breakpoint' where much noise surrounds the expected deterministic breakpoint. We also discuss the concept of the 'interruption of transmission' independent of the 'breakpoint' concept where analyses of model behaviour illustrate the current limitations of deterministic models to account for the 'fade-out' or transmission extinction behaviour in simulations. The analyses based on migration confirm a relationship between the infected human migration rate per unit of time and the death rate of infective stages that are released into the free-living environment (eggs or larvae depending on the STH species) that create the reservoir of infection which in turn determines the likelihood that control activities aim at chemotherapeutic treatment of the human host will eliminate transmission. The development of a new stochastic simulation code for STH in the form of a publicly-available open-source python package which includes features to incorporate many population stratifications, different control interventions including mass drug administration (with defined frequency, coverage levels and compliance patterns) and inter-village human migration is also described. : medRxiv preprint
A stochastic individual-based modelFollowing past publications [12,23], the STH transmission model we introduce here is a stochastic individual-based analogue to the deterministic original given in Refs. [26,11,7]. : medRxiv preprint ∂ ∂Z G jn [Z(t), t] = λ jn Λ j (t) [Z(t) − 1] G jn [Z(t), t] , whose solution is given by Eq. (A.4) when one replaces Z(t ) − 1 with the inverted form of the equation above.
“…If there is potential to shorten the time during which ivermectin donation is needed, this could have profound implications for the business model used today. Moreover, ivermectin has also been demonstrated, in a triple combination, to have remarkable potential impact on elimination lymphatic filariasis [44]. Fig.…”
Section: Policy Pathwaymentioning
confidence: 99%
“…The demand will vary according to the operational goals for onchocerciasis (control, elimination or eradication). One estimate is it could reach up to 2.63 billion treatments for the 2013–2045 period [71], but higher demand due to accelerated LF elimination with drug combo strategies can be expected [44, 47]. …”
Vector control is a task previously relegated to products that (a) kill the mosquitoes directly at different stages (insecticides, larvicides, baited traps), or (b) avoid/reduce human-mosquito contact (bed nets, repellents, house screening), thereby reducing transmission. The potential community-based administration of the endectocide ivermectin with the intent to kill mosquitoes that bite humans, and thus reduce malaria transmission, offers a novel approach using a well-known drug, but additional steps are required to address technical, regulatory and policy gaps. The proposed community administration of this drug presents dual novel paradigms; first, indirect impact on the community rather than on individuals, and second, the use of a drug for vector control. In this paper, the main questions related to the regulatory and policy pathways for such an application are identified. Succinct answers are proposed for how the efficacy, safety, acceptability, cost-effectiveness and programmatic suitability could result in regulatory approval and ultimately policy recommendations on the use of ivermectin as a complementary vector control tool.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-017-1803-2) contains supplementary material, which is available to authorized users.
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