In this study, infrared thermography (IRT) was assessed as a means of detecting foot-and-mouth disease virus (FMDV)-infected cattle before and after the development of clinical signs. Preliminary IRT imaging demonstrated that foot temperatures increased in FMDV-infected animals. The maximum foot temperatures of healthy (n = 53), directly inoculated (DI) (n = 12), contact (CT) (n = 6), and vaccine trial (VT) (n = 21) cattle were measured over the course of FMD infection. A cut-off value was established at 34.4 °C (sensitivity = 61.1%, specificity = 87.7%) with the aim of detecting FMDV-infected animals both before and after clinical signs were observed. Seven of 12 (58%) DI and 3/6 (50%) CT animals showed maximum foot temperatures exceeding the 34.4 °C cut-off before the development of foot vesicles. In contrast, only 5/21 (24%) VT animals displayed pre-clinical foot temperatures above this cut-off possibly indicating partial vaccine protection of this group. These results show IRT as a promising screening technology to quickly identify potentially infected animals for confirmatory diagnostic testing during FMD outbreaks. Further evaluation of this technology is needed to determine the value of IRT in detecting animals with mild clinical signs or sub-clinical infections.
Bibliographical noteFunding Information:
We want to thank Drs. Jose Barrera, John Neilan, and Lazlo Zsak from Plum Island Animal Disease Center (PIADC) for allowing us to collect data during their vaccine trials, and the animal care takers at PIADC for their patience and help collecting the data. We also acknowledge Mr. John Phillips, statistician, NAA-ERRC in Wyndmore, Pennsylvania for statistical advice. KR-L was the recipient of a Plum Island Animal Disease Center Research Participation Program fellowship, administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the US Department of Energy (DOE) and the US Department of Agriculture (USDA). All opinions expressed in this paper are those of the authors and do not necessarily reflect the policies and views of the USDA, DOE, or ORAU/ORISE. This research was funded by ARS-CRIS project 1940-32000-040-00D. The IR camera was made available through the support of the College of Biological Sciences at the University of Minnesota.
- Infrared thermography