|MSOFFE, PETER - Sokoine University Of Agriculture|
|CHIWANGAD, GASPAR - Tanzania Veterinary Laboratory Agency|
|CARDONA, CAROL - University Of Minnesota|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2019
Publication Date: 8/12/2019
Citation: Msoffe, P.L., Chiwangad, G.H., Cardona, C.J., Miller, P.J., Suarez, D.L. 2019. Isolation and characterization of Newcastle disease virus from live bird markets in Tanzania. Avian Diseases. 63(4):634-640. https://doi.org/10.1637/aviandiseases-D-19-00089.
Interpretive Summary: Newcastle disease virus (NDV) is a deadly disease of poultry that is commonly found in Mexico, Central America, south America, Africa, and Asia. Some strains are more virulent than other strains, and it has become common to sequence NDV isolates as a way to characterize them. As part of a surveillance effort, samples from chickens were collected from live bird markets from 5 different provinces in Tanzania. Over 1000 samples were tested for both Newcastle disease virus and avian influenza virus. No avian influenza virus was detected. Almost 10% of the samples had detectable Newcastle disease virus. Over 30 isolates were made and sequenced, which showed two unique genotypes of the virus in the country, although both were equally virulent. This type of information helps prepare the United States for future potential outbreaks.
Technical Abstract: Chickens in live bird markets (LBMs) from six different regions of Tanzania were surveyed for Newcastle disease (ND) virus (NDV) and avian influenza virus in 2012. ELISA-based serology, virus isolation, and characterization, including pathotyping was conducted. Virulent NDV was isolated from almost 10% of the tested samples, with two distinct genotypes being detected. One genotype was similar to recent viruses circulating in Kenya and Uganda, which share a northern border with Tanzania. Several viruses of this genotype were also isolated from Tanzania in 1995, the last time surveillance for NDV was conducted in the country. The second genotype of virus from Tanzania was closely related to viruses from Mozambique, a southern neighbor, and more distantly to viruses from South Africa, Botswana, and several European countries. Partial fusion gene sequence from the isolated viruses showed identical fusion cleavage sites that were compatible with virulent viruses. Selected viruses were tested by the intracerebral pathogenicity index, and all viruses tested had scores of >1.78, indicating highly virulent viruses. Serology showed only a third of the chickens had detectable antibody to NDV, suggesting that vaccination is not being commonly used in the country, despite the availability of vaccines in agricultural-related markets. All samples were taken from clinically healthy birds, and it is believed that the birds were sold or slaughtered before showing ND clinical signs. LBMs remain a biosecurity risk for farmers through the return of live infected birds to the farm or village or the movement of virus on fomites, such as uncleaned wooden cages.