Symbol | Definition | Value and units | References |
---|---|---|---|
x ij | Number of microfilariae in the ith skin snip biopsy from body site j (shoulder, hip or calf) | Data from each participant | |
d ij | Weight of the i th skin snip biopsy from body site j (shoulder, hip or calf) | See Table 1, in mg | |
ε* | Rate of production of microfilariae per (mated) fertile worm per mg of skin | 1.1538 year-1 | [41] |
m * ij | Mean number of microfilariae per skin snip at baseline | For the mean number of mf/mg for each site and setting see Table 1 | |
k m | Aggregation (overdispersion) parameter of skin microfilariae | Estimated by fitting the model, see Table 3 | |
μ m | Per capita rate of microfilarial mortality | 0.8 year-1 | |
w | Number of adult (mated) fertile female worms harboured by the host | Unobserved, assumed to be linearly related to microfilarial load | [39] |
θ W | Mean number of adult (mated) fertile female worms per host | Unobserved, estimated by fitting the model, see Table 3 | |
k W | Aggregation (overdispersion) parameter of adult female worms | Estimated by fitting the model, see Table 3 | |
α = ε *1 /ε *2 | Ratio of the rate of microfilarial arrival in a shoulder or calf skin snip to the rate in a snip from the iliac crest | Estimated by fitting the model, see Table 3 | |
ρ | Rate of resumption of microfilarial production | 0.29 year-1 | |
t | Time since last ivermectin treatment | 1, 3, 5 years | |
ζ | The per dose reduction in female worm fertility caused by ivermectin treatment | 0 | [43] |
0.07 | [54] | ||
0.35 | [55] | ||
n | No. of (annual) ivermectin rounds to which a surviving (mated) female worm has been exposed | 10 | |
x + | The event that any of the skin snips taken from a host are positive |