Seroprevalence of Newcastle disease virus in backyard chickens and herd-level risk factors of Newcastle disease in poultry farms in Oman

Peer review under responsibility of Faculty of Veterinary Medicine, Cairo University.

Figures & data

able 1 Number of sampled flocks (n = 139) and birds (n = 1383) and their seroprevalence to NDV from nine governorates of Oman.

Flock-level seroprevalence
Locations	No. of sampled flocks	NDV positive	No. of chickens	Mean flock size	No. of sampled chickens	NDV positive (%)
North Al Batinah	38	24 (63.2)	6225	159.6	381	143 (37.5)
Ad Dakhliyah	26	15 (57.6)	3620	139.7	260	91 (35.0)
Ad Dhahirah	19	7 (36.8)	2065	147.5	186	52 (27.9)
South Ash Sharqiyah	14	6 (42.8)	2050	146.4	137	44 (32.1)
South Al Batinah	14	5 (35.7)	1530	109.3	135	45 (33.3)
North Ash Sharqiyah	11	5 (45.5)	970	88.2	114	44 (38.6)
Al Buraimi	7	5 (71.4)	540	77.1	71	25 (35.2)
Muscat	6	3 (50.0)	720	120.0	60	19 (31.6)
Musandam	4	2 (50.0)	1170	292.5	39	5 (12.8)
Total (%)	139	72 (51.7)	18,890	136.0	1383	468 (33.8)
Mean ± SD	15 ± 10		2098 ± 1807		154 ± 108

able 2 Association between flock and bird levels NDV seroprevalence in each governorate of Oman.

	Birds		Flocks
Locations	Total number	NDV positive (%)	Total number	NDV positive	χ ^2 value	P value
North Al Batinah	6225	143 (37.5)	38	24 (63.2)	2.02	0.15
Ad Dakhliyah	3620	91 (35.0)	26	15 (57.6)	5.22	0.02
Ad Dhahirah	2065	52 (27.9)	19	7 (36.8)	0.66	0.42
South Ash Sharqiyah	2050	44 (32.1)	14	6 (42.8)	0.66	0.42
South Al Batinah	1530	45 (33.3)	14	5 (35.7)	0.32	1.00
North Ash Sharqiyah	970	44 (38.6)	11	5 (45.5)	0.20	0.75
Al Buraimi	540	25 (35.2)	7	5 (71.4)	3.53	0.21
Muscat	720	19 (31.6)	6	3 (50.0)	0.83	0.39
Musandam	1170	5 (12.8)	4	2 (50.0)	3.68	0.12
Total (%)	18,890	468 (33.8)	139	72 (51.7)

χ ² value = Pearson chi-square statistic.

P value < .05 is considered significantly different.

able 3 Characteristics of farms based on farmers’ reports (n = 500) and the percentage with recorded ND cases.

	ND cases (n = 202)	Not recorded (n = 136)	No information (n = 162)	Total (%)
Product
Meat	134 (66.3)	90 (66.1)	76 (46.9)	300 (60.0)
Egg	42 (20.7)	38 (27.9)	54 (33.3)	134 (26.8)
Mix	26 (12.8)	8 (5.8)	32 (19.7)	66 (13.2)
Management system
Local	68 (33.6)	34 (25.0)	88 (54.3)	190 (38.0)
Open	80 (39.0)	36 (26.4)	52 (32.1)	168 (33.6)
Close	54 (26.7)	66 (48.5)	22 (13.6)	142 (28.4)
Veterinarian
Absent	178 (88.1)	94 (69.1)	158 (97.3)	430 (86.0)
Present	24 (11.9)	42 (30.9)	4 (2.7)	70 (14.0)
Capacity	832,020	1,212,100	2,227,670

able 4 Univariable and multivariable logistic regression models of factors associated with poultry farms (n = 338) with recorded outbreaks of ND in Oman.

	Univariate models			Multivariate models
Item	Odds ratio	95% CI	P-value	Odds ratio	95% CI	P-value
Products
Meat	0.38	0.10–1.45	0.15
Egg	2.71	0.94–7.79	0.06
Mix	Ref
Management system
Open	0.65	0.18–2.33	0.50
Local	0.55	0.23–1.17	0.11
Close	Ref
Veterinarian
Absent	5.37	1.98–14.49	0.001	5.0	2.1–11.7	0.001
Present	Ref			Ref
Vaccination
Yes	8.04	1.45–10.54	0.005
No	Ref
Batch No.	1.62	1.20–2.18	0.002
Vaccine type
Live	0.37	0.03–4.15	0.42	0.97	0.53–1.77	0.93
Dead	1.07	0.10–11.8	0.95	2.28	1.24–4.21	<0.01
Attenuated	1.79	0.09–36.1	0.70	4.84	0.87–26.8	0.07
Notvac	Ref			Ref
Free entry of visitors
Yes	6.32	1.87–21.24	0.003	6.4	2.0–20.3	<0.01
No	Ref			Ref
Farm distance
100–500 m	0.49	0.19–1.27	0.14
500 m–1 km	0.96	0.50–1.84	0.90
Above 1 km	Ref
Staff
No	3.89	1.31–11.06	0.015	3.94	1.46–10.58	<0.01
Yes	Ref			Ref
Biosecurity
Present	0.40	0.41–1.57	0.52
Absent	Ref
Disinfectant
Yes	0.24	1	0.62
No

Ref = reference category.

OR = odds ratio.

P < .05 is significantly different.

able 5 Responses of farmers regarding practices relating to ND outbreaks and correlation between the items.

Items	Frequency	%	Correlation with ND outbreaks
			Spearman correlation coefficient	P-value
Do you report disease outbreaks in your farm to any authority
No	168	83.2	0.065	0.23
Yes	34	16.8
Do you report to a veterinarian
No	166	82.2	−0.005	0.93
Yes	36	27.8
Do you stop selling products during outbreaks
No	86	42.6	0.118	0.03
Yes	116	57.4
Restriction
No	166	82.2	0.168	0.002
Yes	36	27.8
Are you aware of clinical signs of ND
No	128	63.4	−0.014	0.80
Yes	74	36.6
Do you submit samples to appropriate centres?
No	174	86.1	0.07	0.19
Yes	28	13.9