Volume 18, Number 11—November 2012
Research
Litchi–associated Acute Encephalitis in Children, Northern Vietnam, 2004–2009
Table 1
Univariate analyses of Ac Mong encephalitis, Bac Giang Province, Vietnam, 2004–2009
Variable/category | IRR (95% CI)* | p value† |
---|---|---|
Mean altitude, m | ||
<9.85 |
1 | <0.001 |
9.85–16.47 |
1.23 (0.76–1.99) | |
16.47–58.56 |
1.35 (0.83–2.20) | |
>58.56 |
2.93 (1.88–4.56) | |
Presence of a river in the commune | ||
No |
1 | 0.996 |
Yes |
1.00 (0.70–1.43) | |
Litchi surface, % commune surface | ||
<1.49 |
1 | <0.001 |
1.49–5.84 |
1.27 (0.75–2.15) | |
5.84–12.92 |
2.89 (1.82–4.58) | |
>12.92 |
2.73 (1.72–4.35) | |
Rice surface, % commune surface | ||
<6.22 |
1 | <0.001 |
6.22–24.51 |
0.64 (0.42–0.98) | |
24.51–38.42 |
0.61 (0.40–0.93) | |
>38.42 |
0.29 (0.17–0.48) | |
Forest surface, % commune surface | ||
<0.48 |
1 | <0.001 |
0.48–11.13 |
1.81 (1.06–3.09) | |
11.13–40.58 |
3.32 (2.00–5.48) | |
>40.58 |
4.05 (2.45–6.70) | |
Litchi yield, tons/km2 | ||
<157.68 |
1 | 0.083 |
157.68–300.02 |
1.18 (0.75–1.84) | |
300.02–503.51 |
0.97 (0.61–1.54) | |
>503.51 |
1.42 (0.93–2.17) | |
Rice yield, tons/km2 | ||
<460.00 |
1 | 0.500 |
460.00–500.00 |
0.83 (0.54–1.27) | |
500.00–534.15 |
0.78 (0.50–1.21) | |
>534.15 |
0.68 (0.43–1.08) | |
Pigs density, no./km2 | ||
<178.11 |
1 | |
178.11–419.53 |
0.45 (0.29–0.69) | <0.001 |
419.53–681.32 |
0.47 (0.31–0.71) | |
>681.32 |
0.29 (0.18–0.47) | |
Poultry density, no./km2 | ||
<1,449.79 |
1 | <0.001 |
1,449.79–3,715.18 |
0.57 (0.38–0.85) | |
3,715.18–7,065.25 |
0.58 (0.39–0.86) | |
>7,065.25 |
0.21 (0.12–0.37) | |
Buffaloes density, no./km2 | ||
<11.57 |
1 | 0.050 |
11.57–22.85 |
1.91 (1.18–3.11) | |
22.85–35.06 |
1.82 (1.10–2.98) | |
>35.06 |
1.72 (1.04–2.84) | |
Cattle density, no./km2 | ||
<7.04 |
1 | <0.001 |
7.04–49.66 |
0.78 (0.53–1.14) | |
49.66–105.12 |
0.43 (0.28–0.67) | |
>105.12 |
0.27 (0.16–0.44) | |
Mean temperature, °C | ||
January–April | ||
<19.23 |
1 | 0.004 |
19.23–20.16 |
0.74 (0.53–1.04) | |
>20.16 |
0.53 (0.37–0.77) | |
May–August | ||
<27.88 |
1 | <0.001 |
27.88–28.53 |
0.32 (0.21–0.49) | |
>28.53 |
0.81 (0.59–1.12) | |
Mean humidity, % | ||
January–April | ||
<82.07 |
1 | <0.001 |
82.07–83.55 |
0.81 (0.59–1.12) | |
>83.55 |
0.32 (0.21–0.49) | |
May–August | ||
<82.96 |
1 | 0.059 |
82.96–83.84 |
0.72 (0.51–1.02) | |
>83.84 |
0.68 (0.47–0.97) | |
Total rainfall, mm | ||
January–April | ||
<150 |
1 | 0.059 |
150–210 |
0.94 (0.64–1.37) | |
>210 |
1.38 (0.98–1.96) | |
May–August | ||
<518 |
1 | 0.059 |
518–636 |
1.38 (0.98–1.96) | |
>636 |
1.94 (0.64–1.37) |
*IRR, incidence rate ratio.
†Indicates global p value.