Waterborne, abiotic and other indirectly transmitted (W.A.I.T.) infections are defined by the dynamics of free-living pathogens and environmental reservoirs

Miles D. Miller-Dickson; Victor A. Meszaros; Francis Baffour-Awuah; Salvador Almagro-Moreno; C. Brandon Ogbunugafor

One such intervention may be the implementation of needle-exchange programs. Needle-exchange programs are an example of "harm reduction" public health strategies that aim to reduce harm stemming from behaviors that put the affected individuals or communities at risk [65] . These policies are controversial, but have been demonstrated to be effective interventions for HIV and HCV in certain settings [66] . With respect to the HCV WAIT model, some of these programs (especially ones targeting injection equipment, like safe injection sites) can increase the discard rate of infected needles by providing a safe location to use and discard needles, while also providing uninfected needles to IDU. In our model, parameters like the needle discard rate, k i and k u , and π N are affected by needle exchange programs. Figure 6 demonstrates how R 0 is affected by these parameters. One can see that R 0 can be reduced by increasing k i -the infected needle discard rate-along a fixed value of π Nthe birthrate of uninfected needles-and that increasing π N along a fixed value of k i has the same effect. It is also evident that R 0 can be reduced more rapidly by increasing k i and π N simultaneously, as expected. In this way, the proportion of infected needles is reduced because of an increase in clean needles and a reduction of infected ones, lowering R 0 .