Table 2. Bovine leukemia virus infection in cattle in individual and farm levels as detected by ELISA.
| Categories | No. tested | No. positive | Prevalence (%) | ||
|---|---|---|---|---|---|
| Individual level | Location | Hanoi a) | 159 | 20 | 12.6 |
| Bacninh a) | 30 | 9 | 30.0 | ||
| Vinh Phuc | 77 | 15 | 19.5 | ||
| Breed | Dairy cattle b) | 199 | 44 | 22.1 | |
| Beef cattle b) | 67 | 0 | 0.0 | ||
| Gender | Male c) | 34 | 0 | 0.0 | |
| Female c) | 232 | 44 | 19.0 | ||
| Age | ≤1 year old | 49 | 5 | 10.2 | |
| >1; ≤2 years old | 75 | 13 | 17.3 | ||
| >2; ≤3 years old | 74 | 13 | 17.6 | ||
| >3 years old | 67 | 13 | 19.4 | ||
| Undetermined | 1 | 0 | 0.0 | ||
| Total | 266 | 44 | 16.5 | ||
| Farm level | Scale | Small sized farm | 61 | 15 | 24.6 |
| Medium sized farm | 19 | 8 | 42.1 | ||
| Type | Dairy farm d) | 53 | 23 | 43.4 | |
| Beef farm d) | 24 | 0 | 0.0 | ||
| Mixed farm | 3 | 0 | 0.0 | ||
| Total | 80 | 23 | 28.8 | ||
a–d) Prevalence was significantly different (a) P=0.0152, b) P<0.001, c) P=0.0054, d) P<0.001). b–d) There was dependency between gender distribution and breed distribution (χ2=90.08, P<0.05); between gender distribution and farm type distribution (χ2=87.05, P<0.05), indicating that these differences might have been caused by breed effect.