A Cochrane review [Abstract] 1 included 21 trials. Most (14) were before-and-after studies, 5 studies had some control group, 2 studies compared diethylcarbamazine (DEC) -medicated salt with other forms of DEC. Five were efficacy and safety studies of individuals who were all microfilaraemic at baseline; the rest studied endemic communities. Percentage reductions in microfilariae (mf) prevalence were large (43% to 100%) and consistent in most studies with high levels of coverage. Large reductions in mf-density were also observed, though most studies reported changes in mf-density only for people with mf at baseline. Vector infection and infectivity also declined. Changes in disease prevalence were inconclusive as most studies were not powered for this outcome. Adverse events seemed mild. Only two studies compared DEC-medicated salt with other forms of DEC (such as annual or standard 12-day dose), but in both the salt was better. A few studies included longer-term follow up (2 to 19 years). Reductions in mf prevalence, density, and vector infectivity were maintained over time. The DEC concentration in the salt and the duration of intervention were significant factors influencing the percentage reduction in mf prevalence.
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