Dynamics of influenza A virus infections in permanently infected pig farms: evidence of recurrent infections, circulation of several swine influenza viruses and reassortment events

Table 2 Reproduction ratio ( R ), duration of latency and infectiousness estimations for different influenza outbreaks.

Farm	Batch	Age period (days) at SIV infection	SIV subtypes	Exponential growth rate (r) [95% CI]	Latency^ain days (sd)	Infectiousness^bin days (sd)	R^c[95% CI]
A	1	39-56	H1_huN2, H1_avN1	0.15 [0.10 – 0.19]	2.2 (1.0)	5.6 (2.6)	2.5 [1.91-2.94]
A	2	38-64	H1_avN1	0.18 [0.14 – 0.21]	2.2 (0.87)	7.5 (2.4)	3.2 [2.72-3.82]
B	3	106-127	H1_avN1	0.52 [0.31-0.72]	1.4 (0.42)	6.0 (1.5)	6.9 [4.12-10.50]
C	1	42-50	H1_avN1, H1_huN2, rH1_avN2	0.26 [0.10-0.43]	1.4 (0.44)	7.6 (1.1)	4.1 [2.01-6.89]
	2	38-56	H1_huN2	0.19 [0.14-0.25]	5.0 (1.4)	10.4 (2.5)	5.9 [4.23-7.96]

^aDuration associated with Ct > 35 (M gene RT-PCR).
^bDuration associated with Ct ≤ 35 (M gene RT-PCR ).
^cReproduction ratio: number of secondary infections caused by an infectious pig during its entire infectious period.

ISSN: 1297-9716