FOOT-AND-MOUTH DISEASE IN EXPERIMENTALLY INFECTED MULE DEER (ODOCOILEUS HEMIONUS).

The only known outbreak of foot-and-mouth disease (FMD) in wildlife in the US occurred in mule deer (Odocoileus hemionus) in California in 1924-25. There is little recorded information on the pathogenesis and epidemiology of the disease in deer in that outbreak. In this experimental study, we compared the susceptibility of mule deer to FMD virus (FMDV) serotype O to that of cattle (Bos taurus). We also determined the potential for intra- and interspecies transmission of FMDV serotype O in mule deer and cattle, and assessed conventional laboratory tests in their ability to detect FMDV in mule deer. Two mule deer and one steer were each infected by intraepithelial tongue inoculation with 10,000 bovine tongue infective doses of FMDV, strain O1 Manisa. The inoculated steer and deer were kept in the same room with contact animals of both species. Exposed contact animals were moved to rooms with unexposed animals after becoming febrile. All mule deer (n=14) and cattle (n=6) developed clinical signs and lesions consistent with FMDV infection. Deer had a high prevalence of myocarditis and high mortality. Virus was transmitted between mule deer, from cattle to mule deer, and from mule deer to cattle. Virus and antibodies against nonstructural FMDV proteins in mule deer and cattle were detected by conventional laboratory tests. Virus shedding was detected by PCR and virus isolation up to 9 d postexposure in deer.

FOOT-AND-MOUTH DISEASE IN A SMALL SAMPLE OF EXPERIMENTALLY INFECTED PRONGHORN (ANTILOCAPRA AMERICANA).

There is limited information on the pathogenesis and epidemiology of foot-and-mouth disease (FMD) in North American wildlife and none concerning pronghorn ( Antilocapra americana ). In an experimental study of 13 pronghorn and six steers ( Bos taurus ), we compared the susceptibility of pronghorn to FMD virus (FMDV) strain O, with that of cattle ( Bos taurus ). We also determined the potential for intra- and interspecies transmission of FMDV strain O in pronghorn and cattle, assessed the application of conventional laboratory tests in their suitability to detect FMDV infection in pronghorn, and evaluated the potential role of pronghorn as efficient long-term carriers of FMDV. After acclimation to containment at Plum Island Animal Disease Center, two pronghorn and one steer were each infected by intraepithelial tongue inoculation with 10,000 bovine tongue infective doses of FMDV, strain O1 Manisa. Inoculated animals were housed with contact animals. When contact-exposed animals developed fever they were placed in rooms with previously unexposed animals. All inoculated and exposed cattle and pronghorn developed clinical disease typical of FMD. Pronghorn developed severe foot lesions and mild to moderate oral lesions, primarily on the tongue. Duration of clinical signs in both species was 2-3 wk with foot abnormalities evident to the end of the study (51 d postexposure). Other lesions included pancreatitis, myositis of the tongue, and secondary lesions including pleuritis, pneumonia, decubital ulcers, and tenosynovitis. Virus transmission occurred between pronghorn, from cattle to pronghorn, and from pronghorn to cattle. Conventional laboratory tests detected virus and antibodies against nonstructural and structural FMDV proteins in pronghorn and cattle. Virus was present in some animals for 1 wk but was not detectable by virus isolation or PCR at 3 wk postinfection or afterward.

Analysis of clinical samples for early detection of classical swine fever during infection with low, moderate, and highly virulent strains in relation to the onset of clinical signs.

Classical swine fever (CSF) is a transboundary viral disease affecting swine. The clinical course of disease and the best diagnostic samples for early detection were examined using low, moderate, and highly virulent strains of CSFV inoculated into 8-12 week old domestic pigs. Clinical signs were monitored and recorded. Nasal swabs, tonsil scrapings, blood and tonsils were tested using virus isolation, immunohistochemistry, and real-time reverse transcriptase PCR (rRT-PCR).Severe clinical signs appear 3 days post infection (dpi) with the highly virulent strain, correlating with positive tonsil scrapings, tonsil and blood by virus isolation and rRT-PCR (83-100%), whereas nasal swabs become comparable by 5dpi (89-100%). The moderate strain caused less severe clinical signs between 5 and 7dpi, with tonsil scrapings, tonsil and blood positive by 7dpi (83-100%), and nasal swabs were comparable at 10dpi (67-90%). The low virulent strain showed mild clinical signs at 7dpi, with blood, tonsil and tonsil scrapings positive by virus isolation and rRT-PCR. Except for one sample at 10dpi, nasal swabs remained negative throughout the course of infection. This study indicates that irrespective of virulence, whole blood and tonsil scrapings are the sample of choice for early detection of CSFV in live pigs.