Control and eradication of foot-and-mouth disease (FMD) are impeded by the existence of a persistent, subclinical phase of infection in ruminants; animals with this status are referred to as carriers. However, the epidemiological significance of these FMD virus (FMDV) carriers is uncertain. In the current investigation, the contagion associated with FMDV carrier cattle was investigated by exposure of susceptible cattle and pigs to oropharyngeal fluid (OPF) samples or tissues harvested from persistently infected cattle. Naive cattle were inoculated through intranasopharyngeal deposition of unprocessed OPF samples that had been collected from FMDV carriers at 30 days postinfection. These inoculated cattle developed clinical FMD, and the severity of disease they developed was similar to that of animals that had been infected with a high-titer inoculum. In contrast, pigs exposed via intraoropharyngeal inoculation of the same OPF samples or via ingestion of nasopharyngeal tissues harvested from the same cohort of persistently infected cattle did not develop FMD. These findings indicate that there is demonstrable contagion associated with FMDV carrier cattle despite the lack of evidence for transmission by direct contact. The findings presented herein provide novel information that should be considered for FMD risk mitigation strategies.
Bibliographical noteFunding Information:
This work was funded by the U.S. Department of Agriculture Agricultural Research Service CRIS project 1940-32000-061-00D and an interagency agreement with the Science and Technology Directorate of the U.S. Department of Homeland Security under award HSHQDC-11-X-00131.
© 2018 Jonathan Arzt et al.
- Foot-and-mouth disease
- Foot-and-mouth disease virus