-Diagnosis of Carrier State of Foot and Mouth Disease Virus in Vaccinated and Unvaccinated Cattle by Rt-PCR

Abstract

The aim of present work were to investigate the carrier state to foot and mouth disease virus in vaccinated cattle (vaccinated carriers) and unvaccinated cattle (unvaccinated carriers). Reverse transcriptase polymerase chain reaction (RT-PCR) technique was employed to detect FMDV from esophageal and pharyngeal fluid samples collected from both vaccinated and unvaccinated cattle. Results have been shown that the persistence of FMDV is significantly higher in unvaccinated cattle in comparison to vaccinated animals. It have been concluded that high vaccination trials were play a role in the elimination of carrier status from cattle.

Foot-and-Mouth Disease Surveillance Using Pooled Milk on a Large-Scale Dairy Farm in an Endemic Setting

“…However, these previous studies used a homologous or efficacious vaccine to the challenge strain and Leeuw et al (40) only focussed on the detection of infectious live virus instead of FMDV RNA. As there are no other studies known to have considered viral excretion into the milk of vaccinated cattle, data used to inform the model was based on those studies that measured viral excretion from vaccinated and non-vaccinated animals in alternative samples such as nasal fluid, saliva, and esophageal-pharyngeal fluid (26)(27)(28). The authors acknowledge the limitation of this approach, particularly since the quantity and duration of viral excretion seemed to have a substantial impact on the likelihood of predicting a positive result in the milk.…”

“…Previous studies have described a reduced level of virus excretion in nasal fluid, saliva, and esophageal-pharyngeal fluid sample types in vaccinated vs. non-vaccinated animals (26)(27)(28). As the effect of vaccination on the duration of excretion or quantity of FMD virus in the milk is unknown, additional factors were included to account for this possibility, as milk samples in this study were collected from regularly vaccinated cattle.…”

“…As the effect of vaccination on the duration of excretion or quantity of FMD virus in the milk is unknown, additional factors were included to account for this possibility, as milk samples in this study were collected from regularly vaccinated cattle. Data from previous studies were therefore used to inform the model (26)(27)(28)(29), where significantly lower levels of viral excretion (by over 10 2 copies/ml) were observed in vaccinated animals compared with unvaccinated animals. Consequently, in the model prediction for this study, three "levels" of viral excretion were adopted: "1" as described above (no vaccination), and then 10-fold reductions of "1/10" and "1/100" (Figure 2).…”