Volume 15, Number 2—February 2009
Highly Pathogenic Avian Influenza Virus (H5N1) in Frozen Duck Carcasses, 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.