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268 | Schat

Table 9.5 Dates when P2a chicks were hatched, age when serum samples were obtained, and numbers and percentages of dams and
sires that were antibody-positive for chicken infectious anaemia virus. Source: From Schat and Schukken (2010), with permission from the
American Association of Avian Pathologists.
No. positive/total (% positive)
Hatch date
Flock ID (day/month/year) Age in days at test Dams Sires
99–8 a 20/12/1999 168 12/100 (12.0) 2/17 (11.8)
422 42/55 (76.4) 7/13 (53.8)
00–2 a 24/7/2000 125 11/117 (9.4) 1/20 (5.0)
181 55/108 (50.9) 6/20 (30.0)
282 77/81 (95.1) 5/11 (45.5)
01–1 b 5/3/2001 126 51/115 (44.3) 11/17 (64.7)
199 82/109 (75.2) 15/18 (83.3)
258 74/97 (76.3) 11/13 (84.6)
368 77/84 (91.7) 12/14 (85.7)
01–4 b 8/10/2001 121 1/121 (0.8) 0/10 (0.0)
211 1/118 (0.8) 0/10 (0.0)
428 4/97 (4.1) 0/10 (0.0)
02–2 b 20/5/2002 108 14/106 (13.2) 20/20 (100.0)
468 66/88 (75.0) 14/15 (93.3)
03–1 6/1/2003 141 7/108 (6.5) 16/16 (100.0)
253 6/105 (5.7) 18/18 (100.0)
436 9/87 (10.3) 13/13 (100.0)
03–3 4/8/2003 135 1/107 (0.9) 2/20 (10.0)
197 3/100 (3.0) 0/21 (0.0)
464 2/90 (2.2) 0/19 (0.0)
04–1 8/3/2004 166 13/100 (13.0) 3/20 (15.0)
241 14/101 (13.9) 3/19 (15.8)
521 16/91 (17.6) 3/19 (15.8)
04–3 1/11/2004 213 2/101 (2.0) 0/20 (0.0)
437 11/83 (13.3) 3/20 (15.0)
05–2 6/6/2005 191 26/110 (23.6) 4/22 (18.2)
505 22/98 (22.4) 6/20 (30.0)
06–1 9/1/2006 127 24/92 (26.1) 17/22 (77.3)
210 34/91 (37.4) 16/20 (80.0)
265 40/76 (52.6) 19/20 (95.0)
421 33/86 (38.4) 16/20 (80.0)
06–3 18/9/2006 144 0/112 (0.0) 0/20 (0.0)
231 1/112 (0.9) 0/20 (0.0)
445 2/108 (1.9) 0/20 (0.0)
07–2 21/5/2007 135 1/126 (0.8) 0/23 (0.0)
240 1/108 (0.9) 1/21 (4.8)
a Data from Miller et al. (2001).
b Data in part from Schat (2003).

demonstrate that this material was infectious for chickens by the (Engström and Luthman, 1984; Goryo et al., 1987a; Vielitz and
ocular/oral route. Landgraf, 1988; Chettle et al., 1989), suggesting vertical trans-
mission. The vertical transmission can continue up to 6 weeks
Vertical transmission after infection with CAV in an antibody negative parent flock.
Outbreaks of clinical disease with anaemia are infrequently Yuasa and Yoshida (1983) and Hoop (1992) infected antibody-
seen in young birds in broiler and layer flocks and have been negative hens with CAV and demonstrated vertical transmission
associated with young parent flocks lacking antibodies to CAV resulting in anaemia. Hoop (1993) also demonstrated that CAV