Foot-and-mouth disease (FMD) virus causes an acute vesicular disease of domesticated and wild ruminants and pigs. Identifying sources of FMD outbreaks is often confounded by incomplete epidemiological evidence and the numerous routes by which virus can spread (movements of infected animals or their products, contaminated persons, objects, and aerosols). Here, we show that the outbreaks of FMD in the United Kingdom in August 2007 were caused by a derivative of FMDV O1 BFS 1860, a virus strain handled at two FMD laboratories located on a single site at Pirbright in Surrey. Genetic analysis of complete viral genomes generated in real-time reveals a probable chain of transmission events, predicting undisclosed infected premises, and connecting the second cluster of outbreaks in September to those in August. Complete genome sequence analysis of FMD viruses conducted in real-time have identified the initial and intermediate sources of these outbreaks and demonstrate the value of such techniques in providing information useful to contemporary disease control programmes.
BackgroundThermal imagers have been used in a number of disciplines to record animal surface temperatures and as a result detect temperature distributions and abnormalities requiring a particular course of action. Some work, with animals infected with foot-and-mouth disease virus, has suggested that the technique might be used to identify animals in the early stages of disease. In this study, images of 19 healthy cattle have been taken over an extended period to determine hoof and especially coronary band temperatures (a common site for the development of FMD lesions) and eye temperatures (as a surrogate for core body temperature) and to examine how these vary with time and ambient conditions.ResultsThe results showed that under UK conditions an animal's hoof temperature varied from 10°C to 36°C and was primarily influenced by the ambient temperature and the animal's activity immediately prior to measurement. Eye temperatures were not affected by ambient temperature and are a useful indicator of core body temperature.ConclusionsGiven the variation in temperature of the hooves of normal animals under various environmental conditions the use of a single threshold hoof temperature will be at best a modest predictive indicator of early FMD, even if ambient temperature is factored into the evaluation.
We describe the characterization of a foot-and-mouth disease (FMD) serotype A virus responsible for recent outbreaks of disease in Egypt. Phylogenetic analysis of VP1 nucleotide sequences demonstrated a close relationship to recent FMD virus isolates from East Africa, rather than to viruses currently circulating in the Middle East.
The aim of this study was to characterize foot-and-mouth disease (FMD) viruses collected between 2004 and 2008 from Sudan, a country where FMD is endemic. Using virus isolation and antigen ELISA, three FMD virus serotypes (O, A and SAT2) were detected in 24 samples that were submitted to the FAO World Reference Laboratory for FMD. Pan-serotypic real-time RT-PCR assays targeting the 5' untranslated region (5'UTR) and 3D genes of FMD virus were also used to contribute to the laboratory diagnosis of these cases. The lack of concordant results between the real-time RT-PCR assays for three serotype O viruses was attributed to four nucleotide mismatches in the 5'UTR PCR primer and probe sites (three substitutions for the sense-primer and one in the TaqMan(®) probe region). Taken together, the laboratory results showed that recent FMD outbreaks that occurred during 2008 in northern and central Sudan were caused by serotypes O and SAT2, while serotype A was last detected in 2006. Phylogenetic analyses of VP1 sequences from these viruses were used to determine the relationships with 23 older viruses from Sudan and other viruses from West and East Africa. For serotype O, closest genetic identities were between concurrent and historical Sudanese isolates, indicating that within-country circulation is an important mechanism by which FMD is maintained year-on-year in Sudan. A similar pattern was also evident for serotype A and SAT2 viruses; however, these lineages also contained recent representative FMD viral isolates from other countries in the region suggesting that long-distance animal movement can also contribute to FMD dispersal across sub-Saharan Africa. These findings provide the first molecular description of FMD viruses that are circulating in Sudan, and highlight that further sampling of representative viruses from the region is required before the complex epidemiology of FMD in sub-Saharan Africa can be fully understood.
Rapid and accurate diagnosis is essential for effective control of foot-and-mouth disease (FMD). The present report describes the practical steps undertaken to deploy a real-time reverse transcription polymerase chain reaction (real-time RT-PCR) to process the samples received during the outbreaks of FMD in the United Kingdom in 2007. Two independent real-time RT-PCR assays targeting different regions (5'UTR and 3D) of the FMD virus (FMDV) genome were used to confirm the presence of FMDV in clinical samples collected from the first infected premises. Once the FMDV strain responsible had been sequenced, a single real-time RT-PCR assay (3D) was selected to test a total of 3,216 samples, including material from all 8 infected premises. Using a 96-well automated system to prepare nucleic acid template, up to 84 samples could be processed within 5 hr of submission, and up to 269 samples were tested per working day. A conservative cut-off was used to designate positive samples, giving rise to an assay specificity of 99.9% or 100% for negative control material or samples collected from negative premises, respectively. For the first time, real-time RT-PCR results were used to recognize preclinical FMD in a cattle herd. Furthermore, during the later stages of the outbreaks, the real-time RT-PCR assay supported an active surveillance program within high-risk cattle herds. To the authors' knowledge, this is the first documented use of real-time RT-PCR as a principal laboratory diagnostic tool following introduction of FMD into a country that was FMD-free (without vaccination) and highlights the advantages of this assay to support control decisions during disease outbreaks.
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