Risk Factors Associated with Avian Influenza Subtype H9 Outbreaks in Poultry Farms of Central Lowland Nepal

Abstract

Low pathogenic avian influenza (LPAI) of subtype H9 outbreaks have been frequently occurring in major commercial hubs of Nepal including Chitwan, a central lowland area, causing substantial economic losses to the farmers. However, the risk factors associated with these outbreaks have been poorly understood, and hence, this case-control study was conducted in Chitwan, Nawalpur, and Makawanpur districts of Nepal from October 2019 to March 2020. A total of 102 farms were selected in which 51 were case farms, and 51 were controls. Case farms were avian influenza (AI)-subtype-H9-confirmed farms through polymerase chain reaction (PCR) assays on poultry samples. Control farms included farms that were AI-negative in the antigen test brought to the National Avian Disease Investigation Laboratory, Chitwan, for diagnosis during the study period. Each farm was visited to collect information using a semi-structured questionnaire. A total of 25 variables representing farm characteristics and biosecurity measures were considered as potential risk factors. The final multivariable model showed that distance of less than 0.5 km from the main road (OR = 4.04, 95% CI = 1.20–13.56, p = 0.023), distance of less than 1 km from a nearest infected farm (OR = 76.42, 95% CI = 7.17–814.06, p = 0.0003), and wild birds coming around the farm (OR = 6.12, 95% CI = 1.99–18.79, p = 0.0015) were risk factors for avian influenza type H9, whereas using apron or separate cloth inside the shed (OR = 0.109, 95% CI = 0.020–0.577, p = 0.0092) was shown to reduce the risk of farms being positive for AI subtype H9. These findings suggest that due consideration should be given to site selection while establishing the farms and the importance of implementing appropriate biosecurity measures, such as using separate cloth inside the shed and preventing the entry of wild birds inside the farm to reduce the potential risk of introduction of avian influenza type H9 to their poultry farms.

Association of biosecurity and hygiene practices with avian influenza A/H5 and A/H9 virus infections in turkey farms

“…In the present study, no access of visitors into the poultry farms has been reported as a significant protective factor against AIV transmission, whereas the previous studies illustrated that visitors not allowed from other poultry farms and retail markets significantly reduce the odds of AIV transmission ( 80 , 85 ). In our study, we observed that the predicted prevalence of AIV transmission was reported to be only 12% where there were no access visitors to the turkey farms, whereas, in the previous study by Subedi et al ( 86 ), this risk was reported to be 2.8 times higher in commercial farms where visitors are allowed to sheds during the H9 outbreak. Visitors such as veterinarians and technicians visit multiple farms in a day for Newcastle disease (ND) vaccinations without thorough decontamination, contributing significantly to AIV transmission between farms ( 87 ), as ND and AIV frequently co-infect in poultry farms ( 88 ).…”

Knowledge, Attitude, and Practice of Antibiotic Use and Resistance among Poultry Farmers in Nepal

“…Agriculture contributes 25.83% of the national gross domestic product (GDP), while the livestock sector alone contributes 13% of the GDP and 27% of the agriculture GDP [ 11 ]. In Nepal, poultry farming is rapidly expanding, and the country is self-sufficient in the production of chicken meat and eggs [ 12 ]. Around the Kathmandu Valley, there has been a report of high antibiotic usage, including reserve antibiotics for human medicine [ 13 ].…”

Safety and Immunogenicity of ND Vaccines Used in Nepal

“…Viral infections, including avian influenza and Newcastle disease (ND) are the major health problems in the poultry industry of Nepal [1,4,5]. ND is also known as Ranikhet and is caused by Newcastle disease virus (NDV), aka avian paramyxovirus serotype 1, which is a single-stranded RNA virus with non-segmented genome [6].…”