phenylephrine-hydrochloride and Foot-and-Mouth-Disease

The role of foot-and-mouth disease virus (FMDV) carrier cattle in causing new outbreaks is still a matter of debate and it is important to find out these carrier animals by post-outbreak serosurveillance to declare freedom from FMDV infection. In this study we explore the differences in viral shedding between carrier and non-carrier animals, quantify the transmission rate of FMDV infection from carriers to susceptible animals and identify potential viral determinants of viral persistence. We collected nasal and saliva samples from 32 vaccinated and 7 unvaccinated FMDV carrier cattle and 48 vaccinated and 13 unvaccinated non-carrier cattle (total n=100) during the acute phase of infection (up to 28 days post-challenge) and then from limited number of animals up to a maximum 168 days post-challenge. We demonstrate that unvaccinated cattle excrete significantly higher levels of virus for longer periods compared with vaccinated cattle and this is independent of whether or not they subsequently become carriers. By introducing naïve cattle in to the FMDV carrier population we show the risk of new outbreaks is clearly very low in controlled conditions, although there could still be a potential threat of these carrier animals causing new outbreaks in the field situation. Finally, we compared the complete genome sequences of viruses from carrier cattle with the challenge virus and found no evidence for viral determinants of the carrier state.

Topics: Animals; Carrier State; Cattle; Disease Outbreaks; Foot-and-Mouth Disease; Foot-and-Mouth Disease Virus; Genome, Viral; Nose; Saliva; Vaccination; Virus Shedding

In future, a policy of "vaccinate-to-live" may be included in the repertoire of foot-and-mouth disease (FMD) control measures and in support of this approach, we have investigated the hypothesis that vaccine-induced reduction in virus replication and excretion from pigs can be correlated to the severity of clinical signs of FMD by measuring excretion of virus in natural secretions and aerosols. The other aims of this study were to verify the existence of sub-clinical infection in vaccinated pigs, to evaluate the correlation between this and seroconversion to foot-and-mouth disease virus (FMDV) non-structural protein antibodies and to re-examine the occurrence of FMDV persistence in the oro-pharynx of pigs. Therefore, pigs were vaccinated (O1 Manisa) and challenged (O1 UKG) in a manner calculated to produce a broad range of clinical outcomes and were monitored for a minimum of another 33 days post-challenge. Eighty-one percent of the early (10 days vaccinated) challenged pigs and 25% of the late (29 days vaccinated) challenged pigs were clinically infected and all other vaccinated pigs were sub-clinically infected. Although vaccination could not provide complete clinical or virological protection, it reduced the severity of the disease, virus excretion and production of non-structural FMDV antibodies in vaccinated and subsequently infected pigs. As hypothesised, vaccine-induced reduction of virus replication and excretion was found to be correlated to the severity of clinical disease. RNA copies, but no live virus was detected from the pharyngeal and soft palate tissues of a minority of vaccinated and infected pigs beyond the acute stage of the infection.

Topics: Animals; Antibodies, Viral; Body Fluids; Foot-and-Mouth Disease; Foot-and-Mouth Disease Virus; Nose; Oropharynx; Saliva; Swine; Vaccination; Viral Load; Viral Vaccines

The profiles of virus production and excretion have been established for sheep experimentally infected with the UK 2001 strain of foot-and-mouth disease (FMD) virus by inoculation and by direct and intensive contact. Virus replicated rapidly in the inoculated sheep, from which a peak infectivity of airborne virus of 10(4.3) TCID(50) per sheep per 24 h was recovered. Around 24 h later, contact-infected sheep excreted airborne virus maximally. Similar amounts of airborne virus were recovered from cattle. The excretion of virus by the sheep under these conditions fell into three phases. First, a highly infectious period of around 7-8 days. Second, a period of 1-3 days soon afterwards when trace amounts of viral RNA were recovered in nasal and rectal swabs. Third, at 4 weeks after exposure, the demonstration, by tests on oesophageal-pharyngeal samples, that 50% of the sheep were carriers. The implications of the results and the variable role that sheep may play in the epidemiology of FMD are discussed.

Topics: Aerosols; Air Microbiology; Animals; Antibodies, Viral; Cattle; Cattle Diseases; Foot-and-Mouth Disease; Foot-and-Mouth Disease Virus; Nose; Rectum; RNA, Viral; Sheep; Sheep Diseases; Specimen Handling; Virus Shedding

The ability of the portable Cepheid SmartCycler real-time PCR machine to detect foot-and-mouth disease (FMD) virus sensitively and accurately was evaluated by comparing the results of the analyses of nasal swab and serum samples from experimentally infected animals with those obtained from the real-time PCR assay currently in use in the laboratory. The results indicated that the ability of the machine to detect viral RNA is greatly affected by the PCR reagents used for the assay. When it was used with PCR beads it was unable to detect weakly positive samples, but when TaqMan core reagents were used for the assay, its sensitivity was significantly increased. The machine could be used for the laboratory-based detection of FMD; however, as with all assays, significant optimisation of assay conditions as well as solid validation of the technique is required.

Topics: Animals; DNA, Viral; Equipment Design; Foot-and-Mouth Disease; Foot-and-Mouth Disease Virus; Nose; Polymerase Chain Reaction; Predictive Value of Tests; Sensitivity and Specificity; Sheep

Nasal fluid and serum collected from pigs after exposure to live foot and mouth disease (FMD) virus or injection of single oil emulsion (w/o) or double oil emulsion (w/o/w) vaccines were examined for FMD neutralizing activity. After virus exposure the response profiles of serum and nasal mucus were similar to one another. In both, neutralizing activity rose to a peak at one to two weeks after exposure and then subsided slowly. After vaccination with either the w/o or w/o/w preparations a neutralizing response was demonstrable in the serum three to seven days after the first injection, and this was boosted by revaccinations 56 and 117 days later. The neutralizing activity was also detectable in nasal fluid seven days after the first vaccination, but subsequent revaccinations 56 and 117 days later provoked neutralizing titres which were no greater than those observed after the initial vaccination.

Topics: Animals; Antibodies, Viral; Aphthovirus; Foot-and-Mouth Disease; Neutralization Tests; Nose; Swine; Swine Diseases; Vaccination; Viral Vaccines

The pathogenicity of two bovine field strains of virus for indigenous goats was examined in the laboratory. The goats failed to develop clinical disease or become virus carriers although the majority showed a definite immune response. A field survey in a foot-and-mouth disease enzootic area showed that the indigenous sheep and goat populations were frequently exposed to infection as evidenced by a high proportion of sero-positive animals but the incidence of virus carriers was very low in goats and no carriers were detected in sheep.

Topics: Animals; Antibodies; Antigens, Viral; Aphthovirus; Carrier State; Cattle; Cattle Diseases; Esophagus; Feces; Foot-and-Mouth Disease; Goats; Immunity; Kenya; Lymphoid Tissue; Male; Mucus; Nose; Serotyping; Sheep; Species Specificity

Topics: Animals; Aphthovirus; Cattle; Cattle Diseases; Cells, Cultured; Complement Fixation Tests; Cricetinae; Cytopathogenic Effect, Viral; Epithelium; Foot-and-Mouth Disease; Immunodiffusion; Kidney; Male; Nose; Tongue; Virulence; Virus Cultivation

Topics: Animals; Aphthovirus; Carrier State; Cattle; Cattle Diseases; Foot-and-Mouth Disease; Humans; Nose; Swine; Swine Diseases

Sampling of human subjects, who had been in contact with animals infected with foot-and-mouth disease (FMD) virus, showed that virus could be recovered from the nose, throat, saliva and from air expelled during coughing, sneezing, talking and breathing. The amounts of virus recovered paralleled those collected with a large-volume sampler and multistage impinger and these findings confirmed that the highest recovery of airborne virus was from infected pigs followed by cattle and sheep. More virus was found in the noses of those examining infected animals than in those operating the samplers, but there was variation between the subjects. In the majority there was a 1.8 log fall in titre by 3.5 hr., but virus persisted in the nose of one subject for 28 hr. Nose blowing or washing the nostrils did not remove virus completely, nor were cloth or industrial masks completely effective in preventing inhalation of virus. It was possible to transmit virus from infected subjects to others on one occasion. No clinical cases of FMD in man resulted from exposure, nor was there any rise in antibody. Use was made of these findings in determining sites of aerosol excretion in animals, and the results are discussed in relation to FMD in man and to the spread of respiratory viruses by the airborne route.

Topics: Air Microbiology; Animals; Aphthovirus; Cattle; Cattle Diseases; Cough; Foot-and-Mouth Disease; Humans; Masks; Nose; Pharynx; Respiration; Saliva; Sheep; Sheep Diseases; Sneezing; Swine; Swine Diseases

Topics: Animals; Carrier State; Cattle; Cattle Diseases; Foot-and-Mouth Disease; Immune Sera; Immunity, Active; Immunity, Maternally-Acquired; Nose; Pharynx; Vaccination