Table 1.

Farm characteristics, disease-induced mortality and the estimated date of virus introduction for outbreaks of highly pathogenic avian influenza of subtype H5N8 on poultry farms in the Netherlands in 2014 and 2016.

Farm identifier	Farm typea	# Birds in infected house	Estimated cumulative mortality due to disease	Date last recorded mortality	Estimated date of virus introductionb
Chickens 2014
A	Layer	23,459	1519	16/11/2014	01/11/2014
B	Layer	27,840	997	20/11/2014	10/11/2014
C	Layer	28,417	106	29/11/2014	17/11/2014
D	Broiler breeder	6,141	210	20/11/2014	–c
Ducks 2014
E	Meat duck	14,500	115	21/11/2014	–c
Chickens 2016
F	Layer	23,699	656	12/12/2016	05/12/2016
C	Layer	27,369	127	24/12/2016	18/12/2016
G	Broiler breeder	12,296	224	20/12/2016	–c
Ducks 2016
H	Meat duck	7,800	83	01/12/2016	16/11/2016
I	Meat duck	8,550	416	01/12/2016	21/11/2016
E	Meat duck	15,000	105	15/12/2016	26/11/2016

^aAll outbreaks were in flocks that were housed indoors.

^bBased on the mean time of virus introduction with transmission parameter $\beta$ estimated using method A (see “Methods”).

^cThe value of the transmission parameter $\beta$ could not be estimated and therefore the time of virus introduction could not be back-calculated.