Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2007
Publication Date: 9/21/2007
Citation: Chakrabarti, S., King, D.J., Afonso, C.L., Swayne, D.E., Cardona, C.J., Kuney, D.R., Gerry, A.C. 2007. Detection and isolation of exotic Newcastle disease virus from field-collected flies. Journal of Medical Entomology. 44(5):840-844. Interpretive Summary: The primary mode of transmission of exotic Newcastle disease virus (ENDV) is from infected to healthy birds. Identifying other potential modes of transmission is important for the establishment of policies and procedures that will contribute to disease control. Samples of flies were collected at two premises that contained ENDV infected backyard chickens during the 2002-2003 END outbreak in California. Virus was isolated from three fly species, the first report of ENDV isolation from two of those species. Characterization of the recovered ENDV isolates confirmed their identity to isolates from commercial poultry and other birds that were being depopulated to control the outbreak. Although the amount of virus recovered per fly was very low and possibly below the dose required to infect a bird that might consume individual flies, the potential dispersal of infectious virus by flies moving from a premises with infected chickens to a nearby premises with uninfected poultry is a biosecurity concern. Fly control should be included as a component of depopulation of a premises containing infected birds during an eradication program.
Technical Abstract: Flies were collected by sweep net from the vicinity of two small groups of "backyard" poultry (10-20 chickens per group) that had been identified as infected with exotic Newcastle disease virus (ENDV) in Los Angeles County during the 2002-2003 END outbreak in California. Collected flies were subdivided into pools, homogenized in brain-heart infusion broth with antibiotics, and the separated supernatant tested for the presence of ENDV by inoculation into embryonated chicken eggs. Exotic Newcastle disease virus was isolated from pools of Phaenicia cuprina, Fannia canicularis, and Musca domestica. The isolated viruses were identified by hemagglutination inhibition (HI) with Newcastle disease virus (NDV) antiserum. Isolated viruses demonstrated identical monoclonal antibody binding profiles as well as 99% sequence homology in the 374 bp fusion gene sequence when compared to ENDV recovered from infected commercial egg layer poultry during the 2002 outbreak.