Turkey, quail, pheasant) tracheal RNA swab samples were used for AIV RT-qPCR analysis as these viruses primarily replicate in the respiratory tract. For waterfowl, cloacal RNA swab samples were used as AI virus primarily purchase 842-07-9 replicates in the intestinal tract of these birds [16]. Duplicate samples were prepared using a specific matrix gene primer M+25 (59-AGA TGA GTC TTC TAA CCG AGG TCG-39) and M-124 (59-TGC AAA AAC ATC TTC AAG TCT CTG-39) [15]. Chicken GAPDH specific primers were also included on each 96 well plate as an internal control GAPDH+223 (59- GGC ACT GTC AAG GCT GAG AA-39) andSample CollectionBlood (1? ml) was collected from the brachial vein of each bird 12926553 and placed in a serum separator vacutainer. Tracheal and cloacal swabs were also collected, and stored in vials containing 2.5 ml of protein based brain-heart infusion (BHI) transport media. All tubes were labeled with date, species, sample type, and location. Once samples were collected, they were stored at 4uC (24?48 hours) until processed.Biosecurity in Maryland Backyard PoultryTable 1. Outline of dates, locations, and species per sampled backyard flock.Date of Sample CollectionFlock IDRegiona/CountySampled Species Chicken Turkey Duck Guinea Fowl PheasantTotal Birds Sampled7/15/1 2 3 4(N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (E) Wicomico (E) Wicomico (E) Wicomico (E) Wicomico (E) Wicomico (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (S) Charles (S) Charles (S) Charles (S) Charles (E) Dorchester (E) Talbot (E) Caroline (E) Talbot (N) Frederick (N) Carroll (N) Carroll (N) Carroll (N) Frederick6 5 7 6 12 21 3 8 2 6 2 3 6 4 4 6 3 10 6 3 6 6 4 8 6 6 8 4 4 2 4 4 6 4 10 6 6 4 6 227 16 15 2 2 6 2 4 2 2 4 2 1 2 2 2 2 26 5 7 6 12 21 3 8 6 6 6 3 6 6 6 6 3 10 6 3 6 6 5 8 6 6 8 6 8 6 4 8 6 4 18 6 6 4 67/19/6 7 8 97/21/11 12 13 14 157/26/17 18 19 207/28/22 23 24 258/1/27 28 298/3/31 32 338/25/35 36 37 38Totala Region abbreviations (N = North, S = South, E = East). doi:10.1371/journal.pone.0056851.tGAPDH-321 (59- TGC ATC TGC CCA TTT GAT GT-39) [17]. Reaction mixtures included 10 ul of 16 QuantiTect SYBR Green RT-PCR Master Mix, 0.5 ul each of forward and reverse primers of 10 uM concentration (IDT), 0.2 ul of QuantiTect RT mix, 2.3 ul of nuclease free water, 0.5 ul of RNase inhibitor (13Units/ ul) (RNasin, Promega), and 6 ul of RNA extract, for a totalreaction NT 157 volume of 20 ul. Samples were incubated at 50uC for 30 minutes, 95uC for 15 minutes followed by 40 cycles of 94uC at 15 seconds, 60uC at 30 seconds, and 72uC at 30 seconds. A melt curve analysis was conducted with each run. Positive, no template, and no enzyme controls were included on each plate as well.Biosecurity in Maryland Backyard PoultryStatistical AnalysisAfter descriptive data analysis (mean, median, and range), univariate and multivariate statistical analyses were carried out. 
The association of the independent variables elucidated from the questionnaire, such as biosecurity practices and the dependent variables (bird or flock disease positive) were analyzed using Fisher’s exact test, (right sided) for the categorical variables due to small counts (Table 2). Disease status and independent variables of each flock were coded into a binary outcome (Disease = 1, No disease = 0) and (Exposed = 1, Not exposed = 0). Stren.Turkey, quail, pheasant) tracheal RNA swab samples were used for AIV RT-qPCR analysis as these viruses primarily replicate in the respiratory tract. For waterfowl, cloacal RNA swab samples were used as AI virus primarily replicates in the intestinal tract of these birds [16]. Duplicate samples were prepared using a specific matrix gene primer M+25 (59-AGA TGA GTC TTC TAA CCG AGG TCG-39) and M-124 (59-TGC AAA AAC ATC TTC AAG TCT CTG-39) [15]. Chicken GAPDH specific primers were also included on each 96 well plate as an internal control GAPDH+223 (59- GGC ACT GTC AAG GCT GAG AA-39) andSample CollectionBlood (1? ml) was collected from the brachial vein of each bird 12926553 and placed in a serum separator vacutainer. Tracheal and cloacal swabs were also collected, and stored in vials containing 2.5 ml of protein based brain-heart infusion (BHI) transport media. All tubes were labeled with date, species, sample type, and location. Once samples were collected, they were stored at 4uC (24?48 hours) until processed.Biosecurity in Maryland Backyard PoultryTable 1. Outline of dates, locations, and species per sampled backyard flock.Date of Sample CollectionFlock IDRegiona/CountySampled Species Chicken Turkey Duck Guinea Fowl PheasantTotal Birds Sampled7/15/1 2 3 4(N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (S) St. Mary’s (E) Wicomico (E) Wicomico (E) Wicomico (E) Wicomico (E) Wicomico (N) Frederick (N) Frederick (N) Frederick (N) Frederick (N) Frederick (S) Charles (S) Charles (S) Charles (S) Charles (E) Dorchester (E) Talbot (E) Caroline (E) Talbot (N) Frederick (N) Carroll (N) Carroll (N) Carroll (N) Frederick6 5 7 6 12 21 3 8 2 6 2 3 6 4 4 6 3 10 6 3 6 6 4 8 6 6 8 4 4 2 4 4 6 4 10 6 6 4 6 227 16 15 2 2 6 2 4 2 2 4 2 1 2 2 2 2 26 5 7 6 12 21 3 8 6 6 6 3 6 6 6 6 3 10 6 3 6 6 5 8 6 6 8 6 8 6 4 8 6 4 18 6 6 4 67/19/6 7 8 97/21/11 12 13 14 157/26/17 18 19 207/28/22 23 24 258/1/27 28 298/3/31 32 338/25/35 36 37 38Totala Region abbreviations (N = North, S = South, E = East). doi:10.1371/journal.pone.0056851.tGAPDH-321 (59- TGC ATC TGC CCA TTT GAT GT-39) [17]. Reaction mixtures included 10 ul of 16 QuantiTect SYBR Green RT-PCR Master Mix, 0.5 ul each of forward and reverse primers of 10 uM concentration (IDT), 0.2 ul of QuantiTect RT mix, 2.3 ul of nuclease free water, 0.5 ul of RNase inhibitor (13Units/ ul) (RNasin, Promega), and 6 ul of RNA extract, for a totalreaction volume of 20 ul. Samples were incubated at 
50uC for 30 minutes, 95uC for 15 minutes followed by 40 cycles of 94uC at 15 seconds, 60uC at 30 seconds, and 72uC at 30 seconds. A melt curve analysis was conducted with each run. Positive, no template, and no enzyme controls were included on each plate as well.Biosecurity in Maryland Backyard PoultryStatistical AnalysisAfter descriptive data analysis (mean, median, and range), univariate and multivariate statistical analyses were carried out. The association of the independent variables elucidated from the questionnaire, such as biosecurity practices and the dependent variables (bird or flock disease positive) were analyzed using Fisher’s exact test, (right sided) for the categorical variables due to small counts (Table 2). Disease status and independent variables of each flock were coded into a binary outcome (Disease = 1, No disease = 0) and (Exposed = 1, Not exposed = 0). Stren.