Newcastle disease (ND) is a highly contagious viral disease that affects commercial poultry, domestic and backyard poultry. Caused by the Newcastle disease virus that can cause significant losses in poultry, which in many cases include chickens and hens, but is also known to affect turkeys, ducks, geese and other birds.
In this second part of the article we will continue to learn more about Newcastle disease virus (NDV) and review what prevention, biosecurity and vaccination measures are in place to control this disease that continues to be a problem in many countries around the world.
HOSTS AND VIRAL RESERVOIRS
The virus is known to have a wide host range, with at least 236 species classified in 27 of 50 orders of birds being susceptible (Kaleta EF and C Baldauf. 1988).
However, the greatest impact of the disease is on domestic poultry, chickens and hens, both technified and backyard, where the disease can cause large economic losses (Miller and Koch, 2020).
The four panzootics described by Dr. Alexander since 1926, when NDV was first recognized, have involved wild pigeons and imported psittacines in the spread of the virus throughout the world (Figure 2).
However, outbreaks of ND in cormorants in the USA in 2010 and in Chile in 2007, caused by genotype V mesogenic type virus (Diel et al., 2012; Moreno et al., 2009), have been of concern to poultry producers in those countries.
Figure 2. Wild birds associated with virus spread and outbreaks of Newcastle disease virus.
These findings highlight the importance that not only psittacine and columbiform birds represent in the spread of pathogenic strains of the virus, but also wild birds in general, especially in those countries free of vvVEN (Figure 2).
On the other hand, even though it is known that wild birds generally harbor lentogenic strains, while outbreaks in domestic birds are caused by meso or velogenic strains (Sahoo et al., 2022), historical records and phylogenetic sequence analyses available in the gene bank also suggest that:
Virulent viruses currently circulating may have emerged from low virulence viruses of the 1920s-1940s, by mutational changes at the fusion protein cleavage site (Afonso CL, 2021).
Although, multiple studies have attributed to wild birds the responsibility for outbreaks, considering them natural reservoirs of the virus, the analysis of the casuistry of the Laboratory of Avian Pathology (LPA) of the Faculty of Veterinary Medicine of the UNMSM, and recent studies ...
