Abstract
Infectious diseases including Newcastle disease (ND) impair poultry productivity and represent a significant burden to sustainable agriculture in Nigeria. This study aimed to investigate the active circulation and seroprevalence of Newcastle disease virus (NDV) caused by virulent forms of avian paramyxovirus type-1 (APMV-1) in poultry at live bird markets (LBMs) across Nigeria.
A cross-sectional study of 18 LBMs was conducted within three states in Nigeria (Kano, Oyo, and Abuja). Paired swab and tissue samples (n = 413) were collected from birds on FTA cards and tested for APMV-1 using real-time reverse transcription polymerase chain reaction (rRT-PCR). A subset of rRT-PCR-positive samples were selected for whole genome sequencing based on the originating species (chicken, duck, geese), date, and market location to provide a broad range of isolates for characterisation. Blood samples (n = 405) were also collected from birds and the seroprevalence of APMV-1 antibodies was measured using an enzyme-linked immunosorbent assay (ELISA).
APMV-1 RNA was detected in 21.5% (89/413) of samples from LBMs by rRT-PCR. At least one APMV-1 positive sample was detected in 55.6% (10/18) of LBMs. The largest proportion of APMV-1-positive markets was in Kano (83.3%, 5/6), whereas the lowest was in Oyo (16.7%, 1/6). Assessment of genetic data demonstrated that genotype XIV.2 APMV-1 was circulating within Nigeria with the viruses detected clustering closely with other Nigerian isolates described previously. The seroprevalence of APMV-1 in birds was 45.9% (186/405) and 94.4% (17/18) of LBMs had at least one APMV-1 seropositive sample (i.e., with at least one APMV-1-antibody-positive bird). The LBMs in Kano had the lowest seroprevalence (88.3%, 5/6).
This study demonstrated that APMV-1 continues to circulate in LBMs in Nigeria. LBM traders, poultry producers, and related industry and policy stakeholders should be aware of the occurrence of APMV-1 and how ND may negatively impact upon poultry production and the livelihoods of poultry farmers and LBM traders. Training initiatives aimed at improving the knowledge of APMV-1 infection and improvements in biosecurity practises and the role of disease mitigation through vaccination are required to reduce the impact of this threat to food security.