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

Abstract

Newcastle disease (ND) is an endemic disease in Oman’s poultry industry and impacts negatively on food security. However, little is known regarding the potential risks of the disease in backyard poultry. The objectives of this study were to determine the seroprevalence of Newcastle disease virus (NDV) in backyard chickens and the herd-level risk factors in Oman. In total, 1383 serum samples were collected from chickens in 139 flocks from nine governorates. Information on associated risk factors was assessed using a semi-structured questionnaire. The samples were tested using commercial indirect ELISA kits.A logistic regression model was applied to assess the associated risk factors. The bird and flock-level NDV seroprevalence was 33.8% (95% Confidence Interval (CI): 12.8–38.6%) and 57.1% (95% CI: 35.7–71.4%), respectively. The highest seroprevalence of antibody to NDV at bird and flock levels was recorded in North Ash Sharqiyah (38.6%) and Al Buraimi (71.4%), respectively. Also, the lowest seroprevalence at bird and flock levels was recorded in Musandam (12.8%) and South Al Batinah (35.7%), respectively. A significant difference in NDV seroprevalence at flock and bird levels was only recorded in Ad Dakhliyah. Factors associated with higher seroprevalence to NDV included absence of a veterinarian in the farm (OR = 5.3; 95% CI: 2.1, 11.7), usage of dead ND vaccine (OR = 2.3; 95% CI: 1.2–4.2), employment of non-permanent staff (OR = 3.9; 95% CI: 1.5, 10.6) and free entry of visitors (OR = 6.2; 95% CI: 2.0, 20.3). In conclusion, the results of this study revealed a high exposure of backyard chickens to NDV and the identified risk factors could be vital in the prevention and control of the disease in Oman.

Isolation, identification and molecular characterization of Newcastle disease viruses in vaccinated chickens from commercial farms in the Sultanate of Oman

“…ND is regarded as an enzootic disease in Oman [16], [17]. The findings herein with reports of vNDV presence in vaccinated birds could imply increasing replication of the virus, thus precipitating high environmental viral load.…”

“…This is more important with the growing need for the evaluation of the efficacy of existing ND vaccines [5]. In Oman, ND has been identified as a major cause of setbacks in the poultry industry [16], [17]. In this study, we were able to isolate and characterize the NDV responsible for the outbreaks recorded in three large commercial flocks in Oman.…”

“…In Oman, vaccination of birds against ND is little practiced in backyard flocks and recent studies depicted high seroprevalence of NDV in chickens [16], [17]. Additionally, outbreaks of the disease have been reported even in vaccinated commercial flocks [17]. To this moment, the strains of NDV responsible for the outbreaks remain unknown in the country.…”

Serological, clinical, and risk factors of the Newcastle disease on broilers flocks in Algeria

“…For this, we took paired samples; the first sample was taken at the beginning of the disease, while the second sample was taken 2-3 weeks later. In fact, since the concentration of antibodies increases between the two sera collected, this indicates that we had stimulation of the immune system that could be due to a recent infection or to symptomatic viral reactivation [9-11,14,15].…”

“…Alsahami et al . [9] and Bulbule et al . [33] reported that the NDV vaccine of different strains was being used to control clinical disease during the outbreak.…”