Newcastle disease in Nigeria: epizootiology and current knowledge of circulating genotypes

Abstract

Over the years, Newcastle disease (ND) has defied all available control measures. The disease has remained at the forefront of infectious diseases afflicting poultry production after avian influenza. Despite the continuous global use of million doses of ND vaccine annually, the causative pathogen, avian paramyxovirus type 1 also known as Newcastle disease virus (NDV) has continued to evolve causing, even more, a threat not only to the unvaccinated but the vaccinated flocks inclusive. The disease has been well studied in the developed countries where the virus is found in circulation. However, limited information exists on the epizootiology and circulating genotypes of the virus in developing countries where the majority of the flocks are raised on the extensive management system. Identification of virulent NDV in apparently healthy free-range ducks in this system calls for concern and pragmatic approach to investigate factor(s) that favour the virus inhabiting the ducks without clinical manifestation of the disease. Recently, novel genotypes (XIV, XVII, and XVIII) with peculiarity to West and Central African countries have been discovered and due to lack or poor surveillance system possibility of hitherto unreported genotypes are likely. This review elucidates and discusses available literature on the diversity of the circulating NDV genotypes across the West Africa countries and the epizootiology (molecular) of the disease in Nigeria with the view of identifying gaps in knowledge that can assist in the development of effective vaccines and control strategies to combat the peril of the disease.

Genotype Diversity of Newcastle Disease Virus in Nigeria: Disease Control Challenges and Future Outlook

“…They were obtained from Sokoto State in the North and Oyo State from the South. Based on the phylogenetic tree analysis, the two strains are quite related to the isolates from Togo and Ivory-Coast (Figure 1(c)) as earlier reported by Shittu et al [32]. On the contrary, subgenotype XVIIIa isolates are yet to be encountered in Nigeria.…”

“…On the basis of phylogenetic analysis, genotype XVIIa isolates from Nigeria are closely related to those from Niger Republic, Cameroun, Burkina Faso, and Mali whereas the genotype XVIIb isolates, whose mean intrasubgenotype distance was estimated to be 1.5%, are so far exclusively composed of Nigerian strains (Figure 1(c)). Importantly, the ecological distribution of genotype XVII isolates is to date restricted to the West and Central Africa [32, 53] where they are believed to considerably militate against poultry production. Indeed, representatives of these isolates have recently been shown to cause a typical velogenic viscerotropic ND [87] characterized by end stage morbidity and high mortality in chicken.…”

“…In Nigeria, molecular characterization of ND outbreaks was until recently very scanty and largely focused on the partial F gene sequences for phylogenetic grouping of isolates [29, 30]. With the introduction of more objective criteria that utilizes the complete F gene coding sequences for assigning new genotypes [31], the genetic diversity of NDV in Nigeria has become more apparent [32–34]. Unfortunately to date, the consequences of this genetic diversity on disease control using the available vaccines in the country remain poorly addressed.…”

Biological and phylogenetic characterization of a novel hemagglutination-negative avian avulavirus 6 isolated from wild waterfowl in China

“…A tremendous amount of information about AAvV‐1 is available on the characteristics and genetic relationships because of the severe disease it causes in poultries worldwide (Shittu, Joannis, Odaibo, & Olaleye, ; Xue et al., , ; Zhang et al., ). By comparison, the pathological phenomenon which AAvV‐6 causes are relatively weak, just manifested in decreased egg production and mild respiratory disease in turkeys and was avirulent in chickens under normal circumstances (Alexander, ; Saif & Barnes, ; Sobolev et al., ).…”

Prevalence of Newcastle disease virus in feces of free-range turkeys in Enugu, Nigeria

“…Newcastle disease (ND) is the most devastating viral disease of poultry, especially in developing countries, where the majority of the flock is raised on an extensive management system [ 1 ]. The disease is caused by Newcastle disease virus (NDV), an avian orthoavulavirus 1 that belongs to the genus orthoavulavirus , in the subfamily Avulavirinae , and family Paramyxoviridae [ 2 , 3 ].…”