Volume 15, Number 2—February 2009
Research
Highly Pathogenic Avian Influenza Virus (H5N1) in Frozen Duck Carcasses, Germany, 2007
Table
Summary of investigations for HPAIV (H5N1) infections in industrial duck-fattening farms A, B, and C by rRT-PCR, sequencing and serologic analyses, Germany, 2007*
| Farm/barn-unit | Date of housing | Herd size | Date of culling | Cumulative proportion of deaths, % | Duckling age, d | Swab samples† | Serum samples‡ | Tissue samples† |
|---|---|---|---|---|---|---|---|---|
| A/10 | 13 Jul | 12,015 | 25 Aug | 14.4§ | 43 | 50/6 (25 Aug) | 30/30/6 | – |
| A/12 | 16 Jul | 39,165 | 26 Aug | 12.5 | 41 | 50/39 (25 Aug) | 30/13/1 | – |
| A/13 | 13 Jul | 14,000 | 25 Aug | 14.4§ | 43 | 50/23 (25 Aug) | 30/30/4 | – |
| A/15 | 1 Aug | 45,696 | 25 Aug | 10.2 | 25 | 25/13 (22 Aug) | – | – |
| B/1-1 | 29 Jun | 32,540 | 11 Aug¶ | 20.3 (Figure 1, panel C) | 43 | – | – | 7/(1) |
| B/1-1 | 14 Aug | 35,175 | 9 Aug | ND | 24 | 519/0 (5 Sep) | 106/5/0 | – |
| B/1-2 | 17 Aug | 35,000 | 9 Aug | ND | 21 | 511/0 (5 Sep) | 109/5/0 | – |
| B/2-4 | 20 Jul | 35,860 | 9 Sep | 5.9 (Figure 1, panel D) | 50 | 511/6# (5 Sep) | 126/105/52 | 122/1 |
| B/3-5 | 25 Apr | 22,550 | 14 Jun¶ | 12.6 (Figure 1, panel A) | 50 | – | – | – |
| B/3-5 | 20 Jun | 36,300 | 8 Jan¶ | 8.3 (Figure 1, panel B) | 42 | – | – | 34/2 |
| B/3-5 | 7 Aug | 35,860 | 9 Oct | 2.4 | 34 | 515/0 (5 Sep) | 125/3/0 | – |
| B/3-6 | 10 Aug | 34,650 | 9 Oct | 1.2 | 31 | 519/0 (5 Sep) | 130/1/0 | – |
| C | 19 Jul | 28,000 | 9 Oct | 2.2 | 52 | 515/0 (5 Sep) | 91/3/0 | – |
*HPAIV, highly pathogenic avian influenza; rRT-PCR, real-time reverse transcription–PCR; ND, no data available.
†Total number of samples (oropharyngeal swabs; lung and central nervous system tissues) examined by rRT-PCR and sequencing/no. of subtype H5N1-positive samples; date of swab collection is indicated in parentheses.
‡Total number of serum samples examined/nos. positive for nucleocapsid protein–specific antibodies/nos. positive in H5-specific hemagglutination inhibition assay (titer ≥16).
§Combined data on proportion of deaths for barns A/10 and A/13; increased losses in barn A/10 occurred after early August 2007.
¶Date of regular slaughter. HPAIV (H5N1) was found in retained frozen duck carcasses of flocks B/3–5 (hatched 6/20/07) and subtype H5N1–specific RNA was present in 1 frozen duck carcass of flock B/1–1 (hatched 6/29/07), but the sample could not be pathotyped due to low viral genome loads.
#Due to low viral loads the H5N1 pathotype could be confirmed by sequencing a hemaglutinin fragment in only 2 cases.