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.
Poultry production is a major component of the livestock sector in Nigeria and continues to expand rapidly; however, it is still constrained by low productivity. A farm survey was conducted to provide a baseline assessment of poultry production (products generated, farm costs, and revenue), pharmaceutical use, and related challenges faced by farmers on 44 commercial poultry farms in Oyo and Kano states of Nigeria. Live spent layers, eggs, and used beddings were the most frequently sold products for revenue. Antibiotic products were widely used, the most reported were Doxygen, Tylosin, and Conflox. Overall, 40% of farms used feed additives (including toxin binders, minerals, and vitamins) and 12% used coccidiostats. Access to pharmaceutical products was a key challenge and appeared to disproportionally affect farmers in the northern part (Kano) of Nigeria. Other challenges included perceived antibiotic ineffectiveness, high cost of drugs, and long distances to pharmaceutical suppliers. Challenges related to vaccine use were unavailability, distance to the supplier, and health issues interfering with the vaccination schedule. Study findings highlight the need for improved access to veterinary pharmaceuticals, particularly in the northern states. Further investigations into the causes of antibiotic ineffectiveness and strategies for distribution of high-quality, effective pharmaceuticals are also necessary.
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