Quantifying the effect of swab pool size on the detection of influenza A viruses in broiler chickens and its implications for surveillance

Table 5 Predicted HPAIV detection percentage at different days post infection of a broiler flock by testing three (3) dead-bird pooled swab samples of sizes 5, 6 or 11 using lateral flow immunoassay FluDETECT with varying test sensitivities (se) together with 0.3% daily mortality trigger*

Days post flock infection	1	2	3	4	5	6	7
Flock infection prevalence (%) ^#	0.0	0.1	0.4	2.7	13.0	32.5	48.8
1^a
3 pools of 5: se = 71%	6	27	64	88	96	99	100
3 pools of 6: se = 71%	5	29	65	88	96	99	100
3 pools of 11: se = 71%	6	31	69	89	97	99	100
2^b
3 pools of 6: se = 68.1%	5	27	65	88	97	99	100
3 pools of 11: se = 57.9%	5	26	63	85	95	99	100

^*All results i.e. infection prevalence and detected proportions are presented as percentages
^#The mean simulated flock size was estimated as 24,111 birds
^aScenario 1: assuming that LFI test sensitivity for HPAIV is the same across pool sizes
^bScenario 2: assuming that LFI test sensitivity for HPAIV is different across pool sizes

ISSN: 1746-6148