Table 1. CystiAgent model parameters.
| Parameter Description | Parameter Name | Distribution | Value (range, if applicable) | Source |
|---|---|---|---|---|
| Village input features (village-specific) * | ||||
| Humans per household | humans-per-hh | Poisson | 3.8 (3.32–4.94) | RST |
| Proportion of households raising pigs | prop-pig-owners | Binomial | 0.49 (0.25–0.75) | RST |
| Pigs per pig-raising household | pigs-per-hh | Exponential | 2.43 (1.74–4.21) | RST |
| Corral prevalence among pig-owner households | prop-corrals | Binomial | 0.50 (0.23–0.92) | RST |
| Latrine prevalence | prop-latrines | Binomial | 0.64 (0.19–0.97) | RST |
| Live pig trade | ||||
| Proportion of pigs sold prior to slaughter | pigs-sold | Binomial | 0.51 | HH |
| Proportion of sold pigs exported | pigs-exported | Binomial | 0.73 | HH |
| Rate of pigs imported from endemic areas (imports / pig / week) |
pig-import-rate | Constant | 0.00105 | HH |
| Prevalence of cyst infection among imports | import-prev | Binomial | 0.134 | HH |
| Proportion of infected imported pigs with light cyst burden | light-to-heavy | Binomial | 0.76 | HH |
| In-house slaughter and pork sale | ||||
| Pig slaughter age (months) | slaughter-age | Log-normal† | Log-mean = 2.279 (median = 9.8 months); Log-SD = 0.515 |
RST |
| Proportion of pork consumed by owner | hh-only-pork | Binomial | 0.40 | HH |
| Proportion of pork sold after slaughter | sold-pork | Binomial | 0.12 | HH |
| Proportion of shared pork eaten by owner | shared-pork-hh | Binomial | 0.8 | HH |
| Human infection | ||||
| Incubation time to reach tapeworm maturity | tn-incubation | Constant | 8 weeks | [36] |
| Tapeworm lifespan (years) | tn-lifespan | Normal† | Mean = 2 years SD = 0.96 years |
[36,37] |
| Human travel | ||||
| Proportion of households with a frequent traveler | traveler-prop | Binomial | 0.42 | HH |
| Frequency of travel to other endemic areas (every X weeks) |
travel-freq | Constant | 8 weeks | HH |
| Duration of travel | travel-duration | Exponential† | 1.75 weeks | HH |
| Incidence of T. solium taeniasis during travel (risk / person / week) |
travel-incidence | Constant | 0.00023 | [24] |
| Open defecation | ||||
| Latrine-use (prop. of households that “always” use latrine) | latrine-use | Binomial | 0.25 | [39] |
| Radius of environmental contamination (meters from home) | cont-radius | Log-normal† | Log-mean = 3.27 (median = 26 meters) Log-SD = 0.547 |
[39] |
| Rate of egg decay in environment (mean survival duration) | decay-mean | Exponential | 8 weeks | [38] |
| Pig roaming and foraging | ||||
| Proportion of pig households with corrals that “always” corral pigs | corral-always | Binomial | 0.05 | [39] |
| Proportion of pig households with corrals that “sometimes” corral pigs | corral-sometimes | Binomial | 0.57 | [39] |
| Proportion of pigs in “sometimes”-corral-households that are corralled | prop-corral-some | Binomial | 0.32 | [39] |
| Radius of pig roaming “home-range” (meters from home) |
home-range | Log-normal† | Log-mean = 3.79 (median = 44 meters) Log-SD = 0.552 |
[39] |
| Tuning parameters (village-specific) * | ||||
| Probability of human taeniasis upon slaughter of lightly infected pig | pl2h | Binomial | 0.00435 (0.0023–0.0099) | Calibration |
| Probability of human taeniasis upon slaughter of heavily infected pig | ph2h | Binomial | 0.00473 (0.00314–0.0075) | Calibration |
| Probability of exposure to T. solium eggs per human with taeniasis | light-all§ | Binomial | 0.00944 (0.00445–0.0141) | Calibration |
| Probability of exposure to T. solium proglottids per human with taeniasis | heavy-all§ | Binomial | 0.0161 (0.0123–0.0209) | Calibration |
| Probability of light cyst infection upon contact with to T. solium eggs | light-inf | Binomial | 0.286 (0.0137–0.0582) | Calibration |
| Probability of heavy cyst infection upon contact with to T. solium proglottids | heavy-inf | Binomial | 0.00654 (0.0041–0.0116) | Calibration |
| Probability of pig seropositivity upon exposure to T. solium eggs | light-sero | Binomial | 0.316 (0.095–0.67) | Calibration |
| Probability of pig seropositivity upon exposure to T. solium proglottids | heavy-sero | Binomial | 0.286 (0.031–0.82) | Calibration |
* Village input values were measured and applied separately in each village; tuning parameters were calibrated separately for each village; parameter values in these categories are displayed in this table as the mean and range among villages included in the analysis
† Values for these five parameters (slaughter-age, tn-lifepan, travel-duration, cont-radius, and home-range) were applied at the individual pig, human, or household level by randomly assigning a value from the specified statistical distribution (all other parameter values were assigned at the village level).
§ Exposure probabilities (“light-all” and “heavy-all”, x) scaled to the current number of tapeworm carriers (HT) according to 1 − (1–x)HT
Abbreviations: RST = Ring Strategy Trial; HH = Household Survey; SD = Standard Deviation