Age is not a determinant factor in susceptibility of broilers to H5N2 clade 2.3.4.4 high pathogenicity avian influenza virus

Table 1 Transmission study design with mortality results and mean bird infectious and lethal doses

Bird type (age)	Dose (log₁₀ EID₅₀)	Mortality (MDT expressed as dpc or dpe)^a		BID₅₀ and BLD₅₀ (log₁₀)
Bird type (age)	Dose (log₁₀ EID₅₀)	Inoculated	Contact	BID₅₀ and BLD₅₀ (log₁₀)
Broilers (5w)	2	0/5	0/3	5.0
	4	0/5	0/3
	6	5/5 (4.8)	3/3 (5.3)
Broilers (8w)	2	0/5	0/3	5.0
	4	0/5	0/3
	6	5/5 (3.2)	3/3 (4.3)
Broiler breeders (>30w)	2	0/5	0/3	5.0
	4	0/5	0/3
	6	5/5 (3.2)	3/3 (5.7)
	Sham inoculated	0/2	0/2	na
SPF White Leghorns (4w)^b	2	0/5	0/3	3.6
	4	3/5 (2.3)	0/3
	6	8/8 (2)	2/2 (4)
Commercial broad breasted white turkeys (4w)^c	2	0/5	0/3	5.0
	4	0/5	0/3
	6	21/21 (5.9)	3/3 (8)

5w: 5-week old broilers, 8w: 8-week old broilers, >30w: >30-week-old broiler breeders, BID₅₀: mean bird infectious dose, BLD₅₀: mean bird lethal dose, dpc: days post-challenge, dpe: days post-exposure, EID₅₀: mean egg infectious dose, MDT: mean death time, na: not applicable.
^a#dead birds × dpc/total dead birds.
^bFor comparative purposes, data from DeJesus et al. [8] on 4-week old SPF White Leghorn chickens challenged with Tk/MN/15 virus have been added.
^cFor comparative purposes, data from Spackman et al. [9] on 4-week old commercial broad breasted white turkeys challenged with Tk/MN/15 virus have been added.

ISSN: 1297-9716