Table 2.
Variables affecting shedding (assessed as geometric mean shedding and peak shedding) level in chicken, duck, turkey and goose infected with HPAIV.
| Explanatory Variables | Poultry Species | Effect | Difference in Mean Shedding (log10 EID50/mL) a | Difference in Peak Shedding (log10 EID50/mL) a | p (Mean|Peak) |
|---|---|---|---|---|---|
| Pathotype (HPAI vs. LPAI) |
All | Poultry infected with LPAI shed lower levels of virus than poultry infected with HPAI | −1.82 ± 0.33 | −3.14 ± 0.51 | <0.001|<0.001 |
| Shedding route | All | Respiratory shedding is higher than cloacal shedding for all species | 0.43 ± 0.12 | 0.42 ± 0.15 | <0.001|0.005 |
| Turkeyand goose | NS differences between turkeys and geese with chickens | NS | NS | >0.05|>0.05 | |
| Duck | Higher respiratory shedding than chickens | 0.58 ± 0.35 | 0.75 ± 0.39 | <0.001|<0.001 | |
| Lower cloacal shedding than chickens | −1.02 ± 0.38 | −0.93 ± 0.43 | 0.008|0.03 | ||
| Higher respiratory shedding than cloacal | 1.96 ± 0.17 | 2.10 ± 0.31 | <0.001|<0.001 | ||
| Virus origin | Chicken | Shedding is lower when virus originates from birds from the same order than when the virus originates from the same species | −0.89 ± 0.25 | −0.62 ± 0.30 | <0.001|0.04 |
| Shedding is lower when virus originates from birds from different orders than when the virus originates from the same species | −0.92 ± 0.29 | −0.93 ± 0.34 | <0.002|0.007 | ||
| Duck | NS differences in shedding between the origin of the virus | NS | NS | >0.05|>0.05 | |
| Inoculation route | All | NS differences in shedding between intranasal and intrachoanal routes versus contact infected poultry b | NS | NS | >0.05|>0.05 |
| Age | All | Young poultry shed lower than adults c,d | −1.07 ± 0.21 | −1.03 ± 0.25 | <0.001|<0.001 |
| Type | Chicken | NS differences in shedding between broilers and layers | NS | NS | >0.05|>0.05 |
NS = not significant; a the observed differences in mean or peak shedding (in log10) for all subtypes in general. For example: In general, the mean virus shedding in poultry after inoculation of HPAIV is on average almost 2 log10 higher than for LPAIV. b Inoculation lead to slightly higher shedding levels (NS) than contact infections. c Mainly chicken data. d In ducks only young animals were assessed.