Molecular characterization of Newcastle disease virus vaccines in Nigeria.

Background and Aim: Newcastle disease (ND) caused by ND virus (NDV) is a serious impediment to effective poultry production in developing countries such as Nigeria. Despite employing vaccination and other control measures to curtail this disease, its severe forms still persist. This study aimed to confirm the virus strains in the NDV vaccine brands commonly used in Nigeria. Materials and Methods: We employed reverse-transcription polymerase chain reaction (RT-PCR), sequencing, and sequence analysis to characterize NDV strains in four NDV vaccines commonly used in Nigeria. Fragments of 300 bp from NDV fusion genes from the vaccines were amplified. Polymerase chain reaction products were sequenced and analyzed using multiple sequence alignment and phylogenetic analyses to characterize the vaccine viruses as pathotypes. Results: All the vaccines gave positive results, confirming the presence of NDV. Multiple sequence alignment and phylogenetic analyses revealed that two of the vaccines had the lentogenic pathotype, while the other two had the mesogenic or velogenic pathotype. Conclusion: This study provides information to facilitate strategies for regular control of the quality of vaccines in Nigeria.

Co-inections of domestic and wild birds with avian influenza and Newcastle disease viruses: implications for control and genetic mutations.

Co-infections of birds' upper respiratory tract by avian pathogens are common and cause increasing economic losses. This study determines co-infection status of avian influenza (AI) and Newcastle disease (ND) in birds in two Nigerian states with different highly pathogenic avian influenza (HPAI) records and where modified stamping out policy contained the virus for seven years after which the virus resurged with higher infectivity in 2015. A cross-sectional study sampling 910 apparently healthy domestic and 90 wild birds from wild habitats, commercial poultry farms, households and live bird markets (LBMs) was conducted. Cloacal and tracheal swabs were tested for AI H5 and ND viruses using conventional reverse transcriptase polymerase chain reaction (RT-PCR). Overall detection rates of 3% and 18% for AI and ND were obtained. There was an equivalence of 8.5% ND detection rate in poultry and wild birds in the two states. Co-infection (0.2%) of a local chicken from a live bird market (LBM) and crown crane (Balearica regulorum) from a household to AI H5 and ND viruses occurred, respectively. Exposure of birds to AI and ND was significantly detected in apparently healthy domestic and wild birds. The probability of these viruses exchanging genetic materials to resurge with increasing virulence is foreseen. Therefore, routine AI and ND control measures should incorporate virus surveillance and instituting appropriate preventive measures in domestic and wild birds held in households, commercial farms and LBMs.

Seroepidemiology and assessment of risk factors for the spread of avian influenza in birds in two Nigerian states.

Despite modified stamping out eradication policy adopted in Nigeria, there was resurgence in 2015 of highly pathogenic avian influenza (HPAI) H5N1 with greater infectivity. A survey of the risk of spread of HPAI in two HPAI-infected and -uninfected Nigerian states were studied. A cross-sectional study to detect avian influenza (AI) H5 antibodies was conducted using haemagglutination inhibition (HI) test and enzyme-linked immunosorbent assay (ELISA). A total of 950 birds' sera were tested for AI H5 antibodies. Questionnaires were also administered to evaluate risks of AI spread in two states of Nigeria in 2013. AI H5 seroprevalence of 3% and 5% were obtained in Bauchi and Gombe states, respectively. Free flying and captive wild birds had 15% and 11% seroprevalence, respectively. Ninety-two per cent AI awareness and 90% preparedness to report outbreaks of poultry diseases were recorded. Veterinary personnel, radio and television contributed 87% to HPAI awareness. Of the 10 risk categories evaluated, Gombe state had 3 moderate and 1 high risk of AI virus spread. Bauchi state recorded 5 moderate and 1 high risk of AI virus spread. Chi-square analysis showed associations of altitude, temperature, rainfall and presence of live bird markets (LBMs) (P < 0.05) to AI seroprevalence. Odds ratio at 95% CI (1.313-6.333) indicated LBMs presence to be three times more likely to influence AI occurrence. HPAI H5N1 resurged in many states and occurred for the first time in Gombe state in 2015. Veterinary personnel, radio and television may be reliable in changing farmers' attitudes to adopt good biosecurity practices.