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

Table 5 Predicted estimates of prevalence (%) of patent infection for a given (2-snip) sensitivity and observed prevalence of microfilariae

Per ivermectin dose reduction in microfilarial production	1 year after last treatment			3 years after last treatment			5 years after last treatment
Per ivermectin dose reduction in microfilarial production	Sensitivity^a	Prevalence (%)		Sensitivity^a	Prevalence (%)		Sensitivity^a	Prevalence (%)
		Obs^b	Pred		Obs^b	Pred		Obs^b	Pred
0 % reduction per treatment
	31 %	0.25	0.8	67 %	0.25	0.4	76 %	0.25	0.3
		0.5	1.6		0.5	0.7		0.5	0.7
		1.0	3.2		1.0	1.5		1.0	1.3
7 % reduction per treatment
	18 %	0.25	1.4	51 %	0.25	0.5	62 %	0.25	0.4
		0.5	2.8		0.5	1.0		0.5	0.8
		1.0	5.6		1.0	2.0		1.0	1.6
35 % reduction per treatment
	0.6 %	0.25	na^c	3.0 %	0.25	8.3	4.7 %	0.25	5.3
		0.5	na^c		0.5	na^c		0.5	na^c
		1.0	na^c		1.0	na^c		1.0	na^c

^aSensitivity for 2 skin snips based on k _m = 0.42 (mean of the country-specific estimates for 1–10 adult female worms)
^bObserved prevalence based on 2 skin snips
^c na not applicable, we do not present predicted prevalence when greater than 10 % since eqn [6] is only valid when infection is rare

ISSN: 1756-3305