After many laborious months of research, the SGUSVM Department of Paraclinical Studies confirmed that a poxvirus of the genus Avipoxvirus of the Poxviridae family has been isolated from a naturally infected pigeon. Avian pox viruses infect both domestic and wild birds. They do not produce productive infection in humans and other mammalian species. This study is significant, reporting the first successful isolation of a poxvirus from a pigeon in Grenada.
On February 6, 2007 a female domestic pigeon was submitted to the Diagnostic Laboratory at SGU by a client who requested that it be necropsied and diagnosed. The pigeon was found alive in the backyard of the client, apparently ill and unable to fly. It was euthanized and a complete necropsy was performed.
Gross lesions consisting of mild to severe raised crusts were seen on the comb, eyelids and bill. Virus isolation was done by a standard technique involving the inoculation into the chorioallantoic membrane (CAM) of chicken embryos with the putative virus in the cutaneous lesions, because the CAM of developing chicken embryos is one of the sensitive hosts for avian poxvirus isolation. Although the use of embryos from a specific pathogen free (SPF) flock is recommended, in the absence of SPF eggs in Grenada, eggs from a local hatchery (ALS Hatchery in St. George’s, Grenada) were used. This hatchery obtained the fertile eggs from CWT Farms, Gainesville, Georgia, US. Although information on the specific pathogen free status of these eggs is not available, it is interesting to note that all the embryos were susceptible to the virus that resulted in the development of lesions.
This study provides the first evidence of the avian poxviruses in the bird population in Grenada. In September 2003, a poxvirus infection in a canary, based on gross and microscopic lesions, was observed in Grenada, but virus isolation was not attempted.
Upon completion of the report, public service announcements were arranged to inform the Grenadian community of the presence of the “Pigeon Pox” infection in pet birds. Pet bird owners were also advised to use the “Pigeon Pox Vaccine.
Further studies on the genetic and antigenic characterization of the virus are in progress. This study was a collaborative effort between Dr. Ravindra N. Sharma (Associate Director of Research, SGU), his research team (Dr. Muhammad Iqbal Bhaiyat, Dr. Alfred Chikweto, and Ms. Vanessa Matthew, Department of Paraclinical Studies, SVM, SGU) and Dr. Deoki N. Tripathy, Visiting Professor in Veterinary Virology.
Dr. Tripathy is Professor Emeritus at the University of Illinois, Urbana, US. He is a pioneer researcher on pox viruses and since 1984 has been a member of the pox virus study group of the International Committee on Taxonomy of Pox Viruses.
Both Dr. Tripathy and Dr. Sharma recognized the value of this research study as a powerful tool for teaching as well. SGU students in term 4 of the DVM curriculum witnessed first hand the virus isolation techniques using chicken embryos and the lesions produced by avian pox virus in embryos.
The Avian Poxvirus Isolation Study will be submitted for publication in a peer-reviewed scientific journal.