Evaluating Disease Threats to Sustainable Poultry Production in Africa: Newcastle Disease, Infectious Bursal Disease, and Avian Infectious Bronchitis in Commercial Poultry Flocks in Kano and Oyo States, Nigeria

Abstract

The growth of the poultry industry in Nigeria is constrained by major poultry diseases, despite the implementation of vaccination programs. This study aimed to assess the level of protection against Newcastle disease (ND), infectious bursal disease (IBD), and avian infectious bronchitis (IB) afforded by current vaccination schedules and characterize the circulating virus strains in commercial poultry flocks in Nigeria. A cross-sectional study was conducted on 44 commercial poultry farms in Oyo and Kano states of Nigeria. Serum and tissue samples and data on flock, clinical and vaccination records were collected on each farm. Farms were classified as being protected or not protected against ND, IBD and IB based on a defined criterion. Real-time reverse transcription polymerase chain reaction (rRT-PCR) testing was performed for each target virus on tissue samples and positive samples were sequenced. A total of 15/44 (34.1%), 35/44 (79.5%), and 1/44 (2.3%) farms were considered to be protected against ND, IBD, and IB, respectively, at the time of sampling. NDV RNA was detected on 7/44 (15.9%) farms and sequences obtained from 3/7 farms were characterized as the lentogenic strain. Infectious bursal disease virus (IBDV) RNA was detected on 16/44 (36.4%) farms tested; very virulent (vv) IBDV and non-virulent (nv) IBDV strains were both detected in 3/16 (18.8%) positive samples. Sequences of IBDV isolates were either clustered with a group of genotype 3 virulent IBDV strains or were related to vaccine strains MB and D78 strains. IBV RNA was detected on 36/44 (81.8%) farms, with variant02, Massachusetts, 4/91, and Q1 variants detected. Sequences of IBV isolates were either clustered with the vaccines strains Massachusetts M41 and H120 or were most closely related to the D274-like strains or a clade of sequences reported in Nigeria and Niger in 2006 and 2007. This study revealed that most study farms in Oyo and Kano states did not have adequate protective antibody titers against IBV and NDV and were therefore at risk of field challenge. Infectious bursal disease virus and IBV RNA were detected on farms with a history of vaccination suggesting potential vaccination failure, or that the vaccine strains used mismatch with the circulating strains and are therefore not protective.

Baseline Assessment of Poultry Production, Pharmaceutical Product Use, and Related Challenges on Commercial Poultry Flocks in Kano and Oyo States of Nigeria

“…This study was part of a larger project in commercial poultry farms in Kano and Oyo states of Nigeria, which includes two further related papers that: (i) examined baseline parameters on poultry health, management practices, and the related challenges [9], and (ii) investigated flock protection based on antibody titres and characterised circulating strains of Newcastle disease virus (NDV), infectious bursal disease virus (IBDV), and infectious bronchitis virus (IBV) strains in the poultry flocks [8].…”

“…In total, 44 farms were randomly selected (16 in Oyo and 28 in Kano) using probability-proportional-to-size sampling, where the number of farms selected in each state were proportionate to the number of farms present in the state. Detailed information about the sampling approach and the sample size calculation for the farms has been provided elsewhere [8].…”

“…The farms included in this study were located in Oyo (in the southwest geopolitical zone) and Kano (in the northcentral geopolitical zone) states in Nigeria. These states were selected using purposive sampling approach; a map showing the geographical location of the selected states and information on the state selection criteria have been described in detail elsewhere [8].…”

Outbreaks of acute infectious bursal disease of chickens in Maiduguri, Nigeria (2008-2018): retrospective survey

“…There have been several reports of acute IBD outbreaks in both vaccinated and unvaccinated chickens in Nigeria (Ojo et al, 1973;Onunkwo et al, 1975;Uzoukwu, 1981, 1982;Okoye, 1984;Durojaiye et al, 1984, 85;Abdu, 1986Abdu, , 1988Nwosuh et al, 1989; (Igbokwe et al, 2012;Shekaro and Josiah, 2015), improper vaccination at inappropriate age (Abdu, 1986;Bosha and Nongo, 2012;Igbokwe et al, 2020), lack of booster vaccinations (Igbokwe et al, 1996), IBD vaccine or immunization failures (Abdu, 1986), reversion of vaccine virus to virulence (Adamu et al, 2013) and mismatch of vaccine virus with circulating eld virus strain (Ekiri et al, 2021). The phylogenetic analyses of the Nigerian IBDV eld strains revealed a unique cluster related to imported classical and very velogenic IBD virus (vvIBDV) strains (Adamu et al, 2013) and other stains without foreign lineage that are reassortant IBD viruses (Arowolo et al, 2021) showing mutations at the hypervariable regions of VP2 gene (Nwagbo et al, 2018;Arowolo et al, 2021).…”

“…Outbreaks of acute IBD by virulent IBD virus also resulted in ock-speci c mortality of 26-34%(Stoute et al, 2009) and 3-76%(Omer and Khalafalla, 2022). Mortality in the ocks with outbreaks of IBD could be greatly reduced by effective immunization(Ezeibe et al, 2013); but exposure to virulent IBD virus, in ocks with weak immunity against the disease, would often lead to outbreaks associated with high mortalities(Aliyu et al, 2016;Mera et al, 2019;Ekiri et al, 2021).…”