Infection dynamics of foot-and-mouth disease virus in pigs using two novel simulated-natural inoculation methods

In order to characterize foot-and-mouth disease virus (FMDV) infection dynamics in pigs, two simulated-natural inoculation systems were developed and evaluated. Intra-oropharyngeal (IOP) and intra-nasopharyngeal (INP) inoculation both enabled precise control of dose and timing of inoculation while simulating field exposure conditions.     

Acute myeloid leukemia with multilineage dysplasia in an alpaca

An 18-year-old female alpaca was presented to the Colorado State University Veterinary Teaching Hospital for chronic ill thrift over a 1-year period. Six weeks previously, an infected left mandibular cheek tooth was removed by oral extraction. On physical examination the patient was cachectic, lethargic, and weak. Abnormalities on the CBC included neutropenia, thrombocytosis, and severe nonregenerative, macrocytic, hypochromic anemia. Dysplastic nucleated erythrocytes and micromegakaryocytes were observed on the peripheral blood smear. Neutrophils, bands, and metamyelocytes appeared markedly toxic. Numerous blasts containing variable numbers of fine azurophilic granules were also observed. Based on their morphology, the cells were interpreted to be progranulocytes and myeloblasts, and a presumptive diagnosis of acute myeloid leukemia (AML) was made. The blast cells accounted for 60% of the nucleated cell population on bone marrow aspirates, further supporting a diagnosis of AML with multilineage dysplasia. Post mortem examination showed infiltration of the neoplastic cells into spleen, liver, kidney, and lymph nodes. Based on histologic findings, the morphologic diagnoses were disseminated myeloid neoplasia, chronic regionally extensive tooth root abscess, and membranous glomerulonephritis. The neoplastic cells were CD172a-positive on flow cytometry, chloroacetate esterase-positive by cytochemistry, and myeloperoxidase-positive by immunohistochemistry, confirming myeloid origin. To our knowledge, this is the first case of AML with multilineage dysplasia in an alpaca, with only one other case of myelodysplasia described previously in this species.     

Evidence of subclinical foot-and-mouth disease virus infection in young calves born from clinically recovered cow under natural condition

Tropical Animal Health and Production - Foot-and-mouth disease (FMD) is a highly contagious and economically important, transboundary viral disease of cloven-hoofed animals. It is known that an...     

Direct contact transmission of three different foot-and-mouth disease virus strains in swine demonstrates important strain-specific differences

A novel direct contact transmission model for the study of foot-and-mouth disease virus (FMDV) infection of swine was utilized to investigate transmission characteristics of three FMDV strains belonging to serotypes A, O and Asia1. Each strain demonstrated distinct transmission characteristics and required different exposure times to achieve successful contact transmission. While a 4h exposure was sufficient for strain A24 Cruzeiro (A24Cru), both O1 Manisa and Asia1 Shamir transmission required 18h or more. Viral excretion levels from donors (for all three strains) and virus present in room air (for A24Cru and O1 Manisa) were evaluated and associated with clinical signs and observed transmission pattern. Although all directly inoculated donor animals showed acute FMD, A24Cru had the highest levels of viral shedding in saliva and nasal swabs followed by O1 Manisa and Asia1 Shamir. Virus levels in room air were higher and were detected longer for A24Cru than for O1 Manisa. These results provide direct evidence for important strain-specific variation in transmission characteristics and emphasize the need for thorough evaluation of different FMDV viral strains using a well defined contact transmission methodology. This information is critical for vaccine and biotherapeutic efficacy testing, pathogenesis and disease modeling of FMDV transmission.     

Observation of giant diffusivity along dislocation cores

Diffusion of atoms in a crystalline lattice is a thermally activated process that can be strongly accelerated by defects such as grain boundaries or dislocations. When carried by dislocations, this elemental mechanism is known as "pipe diffusion." Pipe diffusion has been used to explain abnormal diffusion, Cottrell atmospheres, and dislocation-precipitate interactions during creep, although this rests more on conjecture than on direct demonstration. The motion of dislocations between silicon nanoprecipitates in an aluminum thin film was recently observed and controlled via in situ transmission electron microscopy. We observed the pipe diffusion phenomenon and measured the diffusivity along a single dislocation line. It is found that dislocations accelerate the diffusion of impurities by almost three orders of magnitude as compared with bulk diffusion.     

Interactive computerized learning program exposes veterinary students to challenging international animal-health problems

This article describes a computerized case-based CD-ROM (CD) on international animal health that was developed to give veterinary students an opportunity to "virtually" work alongside veterinarians and other veterinary students as they try to solve challenging disease problems relating to tuberculosis in South African wildlife, bovine abortion in Mexico, and neurologic disease in horses in Rapa Nui, Chile. Each of the three case modules presents, in a highly interactive format, a problem or mystery that must be solved by the learner. As well as acquiring information via video clips and text about the specific health problem, learners obtain information about the different countries, animal-management practices, diagnostic methods, related disease-control issues, economic factors, and the opinions of local experts. After assimilating this information, the learner must define the problem and formulate an action plan or make a recommendation or diagnosis. The computerized program invokes three principles of adult education: active learning, learner-centered education, and experiential learning. A medium that invokes these principles is a potentially efficient learning tool and template for developing other case-based problem-solving computerized programs. The program is accessible on the World Wide Web at . A broadband Internet connection is recommended, since the modules make extensive use of embedded video and audio clips. Information on how to obtain the CD is also provided.     

Morphologic and phenotypic characteristics of myocarditis in two pigs infected by foot-and mouth disease virus strains of serotypes O or A

Myocarditis is often cited as the cause of fatalities associated with foot-and-mouth disease virus (FMDV) infection. However, the pathogenesis of FMDV-associated myocarditis has not been described in detail. The current report describes substantial quantities of FMDV in association with a marked mononuclear inflammatory reaction, interstitial edema and cardiomyocyte degeneration in the myocardium of two pigs that died during acute infection with either of two different strains of FMDV. Despite similar clinical progression, there was a marked variation in morphological characteristics of myocarditis with a significant difference in intensity of myocardial inflammation between the two cases. Phenotypic characterization of leukocyte populations revealed that in both cases, the inflammatory infiltrate consisted mainly of combinations of CD172a+, CD163+ and CD44+ cells, with a distinct subset of CD8+ cells, but with consistent lack of detection of CD3+ and CD21+ cells. This suggests that the FMDV-associated acute myocardial inflammation in the two observed cases consisted mainly of leukocytes of monocyte lineage, with a distinct population of CD8+ cells which, based on lack of CD3 detection in serial sections, are likely to represent NK cells.