Table 5.
Results of the best GLM (with negative binomial function) of Table 4 explaining the leptospirosis incidence in the villages of Tha Wang Pha and Pua districts (Nan province, Thailand) as a function of habitat characteristics obtained from land cover layers
| Initial model | Explanatory variables | Estimate (s.d.), P | LR χ2, P | Theta (s.d.) | Residual deviance (d.f.) |
|---|---|---|---|---|---|
| Human model 1 (2003–2012) | Patch | −77·8 (19·6), <0·0001 | 14·37, <0·0001 | ||
| Dist Riv | −33·5 (7·5), <0·0001 | 13·79, <0·0001 | |||
| Agri steep | 3·7 (1·1), 0·0009 | 9·99, 0·002 | |||
| Pop | 0·0006 (0·003), 0·05 | 3·51, 0·06 | |||
| Alt | −0·007 (0·006), 0·20 | 2·79, 0·09 | 2·44 (0·72) | 180·1 (161) | |
| Human model 2 (2003–2006) | Dist Riv | −28·4 (10·9), 0·009 | 7·40, 0·007 | ||
| Alt | −0·11 (0·004), 0·012 | 6·95, 0·008 | |||
| Pop | 0·0009 (0·004), 0·019 | 5·63, 0·018 | |||
| Agri steep | 3·2 (1·5), 0·028 | 4·67, 0·031 | |||
| Patch | −41·4 (25·4), 0·10 | 2·51, 0·11 | 2·13 (0·81) | 157·7 (161) | |
| Human model 3 (2007–2012) | Dist Riv | −36·6 (8·1), <0·0001 | 27·49, <0·0001 | ||
| Forest | 7·9 (2·4), 0·0009 | 11·72, 0·0006 | |||
| Agri steep | 11·0 (3·2), 0·0007 | 11·51, 0·0007 | |||
| Agri flat | 6·5 (2·7), 0·016 | 6·32, 0·012 | |||
| Pop | 0·0006 (0·0004), 0·11 | 2·39, 0·12 | 1·81 (0·74) | 157·2 (161) | |
| Human model 4 (2008–2009) | Patch | −0·77 (0·31), 0·014 | 6·2, 0·01 | ||
| Alt | −0·010 (0·005), 0·11 | 3·86, 0·049 | |||
| Dist Riv | −0·21 (0·17), 0·061 | 3·62, 0·050 | |||
| Pop | 0·0008 (0·0005), 0·12 | 2·50, 0·11 | |||
| Agri flat | −0·14 (0·09), 0·14 | 2·33, 0·13 | 2·07 (1·66) | 126·2 (161) |
Four initial models were tested: human model 1 (2003–2012); human model 2 (2003–2006); human model 3 (2007–20012); human model 4 (2008–2009). Each model included the following explanatory variables: population size (Pop), altitude (Alt), distance from river (Dist riv), cover of agriculture on steep land (Agri steep), cover of agriculture on flat land (Agri flat), cover of forest (Forest), cover of human settlement (Settl) and patch density (Patch). Explanatory variables were ranked according to their contribution to the model. [Theta and s.d. of the negative binomial distribution; LR χ2 = likelihood ratio χ2 test for test of fit for explanatory variable; residual deviance with degrees of freedom (d.f.); global fit given by Wald test.]