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Table 5 The effect of annual ivermectin treatment coverage on the microfilarial prevalence and intensity of onchocerciasis infection and its associated morbidity and mortality according to baseline endemicity

From: Modelling the impact of ivermectin on River Blindness and its burden of morbidity and mortality in African Savannah: EpiOncho projections

Pre-control endemicity‡ Mesoendemic Hyperendemic Highly hyperendemic
Therapeutic coverage 60% 80% %change 60% 80% %change 60% 80% %change
Skin microfilarial prevalence§ (%) 3.46 1.84 47% 9.52 4.74 50% 27.53 16.69 39%
Microfilarial intensity§ (mf/mg) 1.08 0.49 55% 3.1 1.31 58% 11.14 5.47 51%
Blindness prevalence§ (%) 0.299 0.297 0.67% 0.95 0.91 4% 4.25 4.13 3%
Visual impairment prevalence§ (%) 0.4015 0.4014 0.02% 1.27 1.22 4% 5.7 5.54 3%
Troublesome itch prevalence§ (%) 2.79 1.80 36% 9.43 3.73 32% 17.38 14.09 19%
Excess mortality annual incidence§ (per 1000) 0.09 0.08 11% 0.29 0.26 10% 1.39 1.13 19%
  1. §Values correspond to model outputs 12 months after the 15th annual ivermectin treatment assuming perennial transmission, 0.1% of systematic non-compliance (high treatment adherence) and a 7% cumulative, per ivermectin dose, reduction in the rate of microfilarial production by adult female worms. Microfilarial infection intensity is quantified as arithmetic mean microfilarial load per mg of skin in those aged ≥ 20 years.
  2. Proportional (percent) reduction in parasitological, morbidity and mortality indicators relative to the lower (60%) treatment coverage of the total population (overall therapeutic coverage).
  3. ‡ Pre-control microfilarial prevalence as in Table 1.