Table 4.
Risk factors considered in the analysis of PRRS occurrences in Thailand
| Categories | Variables |
|---|---|
| Number of pigs per sub-district by type |
(i) number of native pigs, (ii) number of breeding boars, (iii) number of breeding sows, (iv) number of breeding piglets, and (v) number of fattening pigs |
| the number of pig farms per sub-district |
(i) number of farms with native pigs, (ii) number of farms with breeding boars, (iii) number of farms with breeding sows, (iv) number of farms with breeding piglets, and (v) number of farms with fattening pigs. |
| Pig density* |
(i) native pig density, (ii) breeding boar density, (iii) breeding sow density, (iv) breeding piglet density, and (v) fattening pig density |
| Farm density** |
(i) density of farms with native pigs, (ii) density of farms with breeding boars, (iii) density of farms with breeding sows, (iv) density of farms with breeding piglets , and (v) density of farms with fattening pigs |
| The number of pigs per farm |
(i) number of farms with less than 25 heads of pigs, (ii) number of farms with less than 50 heads of pigs, (iii) number of farms with less than 100 heads of pigs, (iv) number of farms with less than 500 heads of pigs, (v) number of farms with less than 1000 heads of pigs, and (vi) number of farms with more than 1000 heads of pigs |
| Farm types*** |
(i) number of farms with breeding boars and sows, (ii) Number of farms with breeding boars, breeding sows, and breeding piglets, (iii) number of farm with breeding boars, breeding sows, breeding piglets, and fattening pigs, and (iv) number of farms with breeding sows and breeding piglets |
| Road density**** |
(i) road1 density, (ii) road2 density, (iii) road3 density, (iv) road4 density |
| sub-district level human population counts | Total human population |
Thirty-five explanatory variables in 8 categories included in analyses of PRRS occurrences in Thailand, estimated at the sub-district level.
*calculated by no. of pig divided by sub-district area (km2).
**calculated by no. of farm divided by sub-district area (km2).
***farms categorized by types of breeding pigs and fattening pigs (not included the native pigs).
****calculated by length of road divided by sub-district area (km2).