Assessment of Fecal Viral Shedding as an Adjunct Diagnostic Test During Quarantine of Snakes
Negative-staining electron microscopy (EM) of feces is an underutilized methodology for testing snakes in quarantine for viruses. Polymerase chain reaction (PCR) testing may be performed as follow-up on positives. This testing was initiated to allow viral screening in snakes too small to safely collect a blood sample for paramyxovirus serology, with the rationale that paramyxovirus presence in feces could be significant.
EM examination was adopted by the Jacksonville Zoo and Gardens as a trial quarantine screening test. Fecal samples were collected from snakes in quarantine and frozen in two aliquots at −80˚C. One aliquot was submitted to Kissimmee (Florida) Diagnostic Laboratory for EM. The second sample was retained for PCR to discern the identity of the virus. In snakes of sufficient size for blood sampling, paramyxovirus serology was performed as well.
Thirty-eight samples were screened from 18 species. Although no paramyxovirus was identified on EM, an adenovirus, a coronavirus and a parvovirus were seen. The adenovirus proved to be a novel atadenovirus by PCR at the University of Florida College of Veterinary Medicine. No PCR was available for parvovirus. The coronavirus was PCR negative, although this assay has not been validated for any reptile coronavirus to date. Each of the respective snakes in which virus was identified have died and on necropsy had pathology grossly and histopathologically.
This testing methodology has potential for identifying individuals with viral infections during quarantine or as clinical concerns. This information can be used as a basis for management decisions.
The authors wish to thank Dr. Elliott Jacobson for his inspiration to add to the database of information relative to viral diseases and his recommendation to utilize negative staining EM. Also, thanks are extended to Woody Fraser and his staff at Kissimmee Diagnostic Laboratory, Florida Department of Agriculture and Consumer Services, Division of Animal Industry for their electron microscopy work and April Childress at the University of Florida for her assistance with the PCR.