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Table 3 Univariate analysis of risk factors for avian influenza virus in backyard poultry

From: Risk factors for avian influenza virus in backyard poultry flocks and environments in Zhejiang Province, China: a cross-sectional study

Factors n Influenza A virus χ 2 P-value
Negative (%) Positive (%)
Polyculture of flocks from various sources
 No 229 221 (96.51) 8 (3.49) 0.77a
 Yes 123 118 (95.93) 5 (4.07)   
Types of live poultry      
 1 195 191 (97.95) 4 (2.05) 6.170 0.013b
 2 135 129 (95.56) 6 (4.44)   
 3 22 19 (86.36) 3 (13.64)   
Number of live poultry
  ≤ 19 230 225 (97.83) 5 (2.14) 0.07a
  ≥ 20 122 114 (93.44) 8 (6.56)   
Type of nesting area
 Enclosed 127 121 (95.28) 6 (4.72) 0.305 0.581
 Open 200 193 (96.50) 7 (3.50)   
Nesting area(m2)
  ≤ 19 161 154 (96.65) 7 (4.35) 0.604 0.437b
 20–49 105 101 (96.19) 4 (3.81)   
  ≥ 50 86 84 (97.67) 2 (2.33)   
Type of raising
 Free ranging 200 194 (97.00) 6 (3.00) 1.284 0.257
 In captivity 127 120 (94.49) 7 (5.51)   
Clean practice of premises
 No 241 229 (95.02) 12 (4.98) 0.197a
 Yes 82 81 (98.78) 1 (1.22)   
Disinfection practice of premises
 No 291 279 (95.88) 12 (4.12) 1.000a
 Yes 22 32 (9.88) 1 (3.03)   
Sanitary condition of premises
 Poor 131 121 (92.37) 10 (7.63) 7.407 0.006b
 Average 189 186 (98.41) 3 (1.59)   
 Good 8 8 (100) 0 (0.00)   
Flocks vaccination history
 Yes 65 64 (98.46) 1 (1.54) 0.477a
 No 261 249 (95.40) 12 (4.60)   
Human infection(H7N9) identified nearby
 Yes 46 43 (93.48) 3 (6.52) 0.405a
 No 281 271 (96.44) 10 (3.56)   
Sick or dead flock
 Yes 341 329 (96.48) 12 (3.52) 0.236a
 No 7 6 (85.71) 1 (14.29)   
Poultry source
 From market 280 268 (95.71) 12 (4.29) 0.481a
 Not from market 72 71 (98.61) 1 (1.39)   
  1. a Fisher exact test
  2. b Trend chi-squared test
  3. − Not applicable