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Table 3 Parameter estimates obtained by fitting a model for the number of microfilariae in a skin snip to data collected in four countries (notation as in Table 2)

From: Modelling Neglected Tropical Diseases diagnostics: the sensitivity of skin snips for Onchocerca volvulus in near elimination and surveillance settings

   Guatemala Venezuela Ghana Cameroon
Aggregation of microfilariae as a function of (unobserved) female worm burdena k m     
1–10 adult female worms   0.35 (0.27, 0.46) 0.48 (0.32, 0.73) 0.54 (0.41, 0.70) 0.29 (0.26, 0.32)
11–30 adult female worms   0.60 (0.47, 0.76) 0.50 (0.31, 0.80) 1.25 (1.01, 1.55) 0.69 (0.56, 0.85)
>30 adult female worms   1.42 (1.13, 1.78) 1.35 (1.00, 1.82) 2.75 (1.74, 4.34) 1.77 (1.45, 2.17)
Mean burden of fertile female worms (range across villages) θ W 15–19 0.4–50 15b 5–16
Aggregation of female worm burden (range across villages) k W 0.38–0.52 0.02–0.59 2.27b 0.31–0.50
Ratio of microfilarial arrival rate in the two body sites sampled per setting (relative to iliac crest)a α 1.08 (0.95, 1.22)
(shoulder/hip)
0.34 (0.28, 0.43)
(shoulder/hip)
0.57 (0.49, 0.66)
(calf/hip)
1.0 (0.81, 1.21)
(calf/hip)
  1. aEstimates presented with 95 % Wald confidence interval
  2. bToo few data per village for village-specific estimates