Table 1

Number and proportion of serum samples testing H5 antibody positive in three serological tests in ducks experimentally infected with H5N1
Test results Pre-inoculation 8 dpi 15 dpi 22 dpi 29 dpi 34 dpi Overall
N HI-CRBC pos 0 4 8 8 7 7 34
Prop HI-CRBC pos 0 0.4 0.8 0.8 0.7 0.7 0.57
(95%-CI)1,2 (0–0.31) (0.12-0.74) (0.44-0.98) (0.44-0.98) (0.35-0.93) (0.35-0.93) (0.33-0.81)
N HI-HRBC pos 0 7 8 7 7 7 36
Prop HI-HRBC pos 0 0.7 0.8 0.7 0.7 0.7 0.60
(95%-CI)1,2 (0–0.31) (0.35-0.93) (0.44-0.98) (0.35-0.93) (0.35-0.93) (0.35-0.93) (0.33-0.87)
N VN pos 0 2 8 8 8 9 35
Prop VN pos 0 0.2 0.8 0.8 0.8 0.9 0.58
(95%-CI)1,2 (0–0.31) (0.03-0.56) (0.44-0.98) (0.44-0.98) (0.44-0.98) (0.55-1.00) (0.40-0.76)

A titre cut-off of ≥ 4 log2 (16) was used to distinguish between positive and negative results. Ten ducks were sampled before inoculation and at 8, 15, 22, 29 and 34 days after virus inoculation. Abbreviations: HI-CRBC (Haemagglutination inhibition test using chicken red blood cells), HI-HRBC (Haemagglutination inhibition test using horse red blood cells), VN (Virus neutralisation test), N (number), Prop (proportion), dpi (day post inoculation), CI (confidence interval).

1Binominal exact confidence intervals were calculated for the proportion of positives at each sampling period.

2Confidence intervals for the overall proportion of positives were adjusted for a clustering of birds by sampling period (10 clusters).

Wibawa et al.

Wibawa et al. BMC Veterinary Research 2012 8:117   doi:10.1186/1746-6148-8-117

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