Volume 13, Number 9—September 2007
Research
Landscape Elements and Hantaan Virus–related Hemorrhagic Fever with Renal Syndrome, People’s Republic of China
Table 1
HFRS incidence at different levels of landscape elements, China*
Incidence (95% CI)† | p value‡ | Odds ratio (95% CI) | |
---|---|---|---|
Elevation, m | |||
<100§ | 3.48 (3.41–3.52) | – | 1.00 |
100–200 | 7.29 (7.16–7.43) | <0.001 | 2.10(2.05–2.16) |
201–500 | 5.17 (5.09–5.26) | <0.001 | 1.49(1.46–1.53) |
501–1,000 | 2.97 (2.88–3.06) | <0.001 | 0.86(0.83–0.89) |
1001–1,500 | 1.76 (1.71–1.88) | <0.001 | 0.36(0.34–0.38) |
1,501–2,000 | 0.32 (0.27–0.38) | <0.001 | 0.09(0.08–0.11) |
2,001–3,000 | 0.85 (0.75–0.96) | <0.001 | 0.24(0.22–0.28) |
>3,000 |
0.71 (0.53–0.92) |
<0.001 |
0.20(0.15–0.27) |
NDVI | <0.001‡ | ||
0–0.1§ | 1.14 (1.06–1.23) | 1.00 | |
0.1–0.2 | 4.21 (4.13–4.29) | <0.001 | 3.69 (3.42–3.99) |
0.2–0.3 | 4.55 (4.51–4.61) | <0.001 | 3.99 (3.70–4.30) |
>0.3 |
1.43 (1.36–1.50) |
<0.001 |
1.25 (1.15–1.37) |
Precipitation, mm/y | <0.001‡ | ||
0–400§ | 0.18 (0.14–0.22) | – | 1.00 |
401–800 | 6.42 (6.34–6.51) | <0.001 | 36.21 (29.23–45.41) |
801–1,200 | 3.65 (3.58–3.70) | <0.001 | 20.51 (16.56–25.74) |
>1,200 |
2.64 (2.60–2.69) |
<0.001 |
14.91 (12.03–18.70) |
Annual cumulative air temperature, °C | <0.001‡ | ||
0–1,600§ | 10.18 (9.96–10.39) | – | 1.00 |
1,601–3,400 | 1.44 (1.38–1.51) | <0.001 | 0.15 (0.14–0.16) |
3,401–4,500 | 8.01 (7.89–8.12) | <0.001 | 0.84 (0.82–0.86) |
4,501–8,000 | 2.56 (2.52–2.59) | <0.001 | 0.27 (0.26–0.27) |
>8,000 |
0.19 (0.10–0.34) |
<0.001 |
0.02 (0.01–0.03) |
Land surface temperature, °C | <0.001‡ | ||
<28§ | 10.75 (10.51–10.99) | – | 1.00 |
28–31 | 2.62 (2.51–2.73) | <0.001 | 0.24 (0.23–0.26) |
32–34 | 2.86 (2.79–2.93) | <0.001 | 0.27 (0.26–0.274) |
35–37 | 4.68 (4.63–4.74) | <0.001 | 0.43 (0.42–0.45) |
>37§ | 0.98 (0.93–1.03) | <0.001 | 0.09 (0.09–0.10) |
*HFRS, hemorrhagic fever with renal syndrome; CI, confidence interval; NDVI, normalized difference vegetation index.
†Incidence = number of HFRS cases/100,000 population.
‡p value of each landscape element; others are p value of subdivision analyses.
§Reference group.