Infecção por Corynebacterium pseudotuberculosis em equinos: aspectos microbiológicos, clínicos e preventivos / Corynebacterium pseudotuberculosis infection in horses: clinical, microbiological and prevention aspects

Corynebacterium pseudotuberculosis é o agente causador da linfadenite caseosa em caprinos e ovinos, sendo responsável por significativas perdas econômicas na ovinocaprinocultura mundialmente. Esta bactéria Gram-positiva também infecta equinos, causando desde quadros assintomáticos até infecções sistêmicas, podendo levar o animal a óbito. Especificamente no Brasil, não foram relatados casos de infecção em equinos, mas acredita-se que, devido à convivência de pequenos ruminantes infectados com equinos em diversas propriedades rurais, seja natural que ocorra a infecção desses animais. A presente revisão tem como objetivo fornecer informações sobre a bactéria C. pseudotuberculosis, sobre os aspectos epidemiológicos e clínicos da infecção em equídeos, bem como sobre técnicas de manejo para sua prevenção...

Corynebacterium pseudotuberculosis is the etiologic agent of caseous lymphadenitis in sheep and goats, an infectious disease that is responsible for significant economic losses in small ruminants breeding units worldwide. This Gram-positive bacterium can infect horses, causing symptomatic disease to systemic infections, which can lead to animals' death. Specifically in Brazil, there are no scientific records of equine infections, but it is believed that, due to the maintenance of infected small ruminants in close association to horses in many properties, the infection of horses may be a reality. The present work had the objective to present information on the bacteria C. pseudotuberculosis, on the epidemiological and clinical aspects of the infection in horses, as well as information about breeding procedures that can be adopted in order to prevent the infection...

Association between haptoglobin and IgM levels and the clinical progression of caseous lymphadenitis in sheep.

BACKGROUND: Sheep caseous lymphadenitis (CLA), caused by Corynebacterium pseudotuberculosis (Cp), is associated with direct economic losses and presents significant zoonotic potential. Despite the importance of the disease, a satisfactory vaccine model has not been developed. Thus, this study aimed to investigate the association between haptoglobin (Hp) and IgM levels and the clinical progression of CLA in primarily infected sheep and in sheep immunized with Cp- secreted antigens adjuvanted with Quillaja saponaria saponins. These animals were kept with CLA-positive sheep to simulate natural exposure that occurs in field conditions. During the experiment, the Hp and IgM levels were monitored for 21 days, and the development of internal CLA lesions was investigated through necropsies on day182 post-immunization. RESULTS: Primarily infected sheep in Group 2 (inoculated with 2x105 Cp virulent strain) had higher Hp values between the first and ninth days post inoculation (PI) than sheep in Group 1 (control; P < 0.05). Immunized animals in Group 3 had significantly higher Hp values between the third and seventh days PI, compared with the control group (P < 0.01). Binary logistic regression (BLR) analysis of primarily infected sheep indicated an association between Hp concentration and CLA clinical progression: animals with high Hp values had 99.9% less risk of having CLA abscesses than animals with low Hp levels (Odds ratio = 0.001, P < 0.05). Both experimental groups had significantly higher IgM titers than the control group around the ninth and eleventh days PI (P < 0.05). The BLR analysis for immunized sheep indicated an association between IgM levels and clinical progression: sheep with high IgM titers had 100.0% less risk of having CLA abscesses than animals with low IgM levels (Odds ratio = 0.000, P < 0.05). CONCLUSIONS: Resistance to C. pseudotuberculosis infection is supported by the early acute phase response, in which up-regulation of Hp and IgM were predictive of a lower risk of CLA lesion development. Because the immunogen used in this study induced a high production of both Hp and IgM, Q. saponaria saponin should be considered a promising candidate in vaccine formulations against sheep CLA.

Haptoglobin and fibrinogen concentrations and leukocyte counts in the clinical investigation of caseous lymphadenitis in sheep.

BACKGROUND: Corynebacterium pseudotuberculosis is the etiologic agent of caseous lymphadenitis (CLA), a disease that affects small ruminants and is responsible for economic losses, including condemnation of carcasses and damaged hides. OBJECTIVE: The goal of this study was to determine if serum haptoglobin and plasma fibrinogen concentrations and peripheral blood leukocyte counts are biologic markers of CLA in sheep. METHODS: Blood from 38 clinically healthy Santa-Inês ewes selected and segregated from a commercial flock of 2500 sheep in an area endemic for C. pseudotuberculosis was collected every 30 days for 6 months. An indirect ELISA was used to detect IgM and IgG antibodies against C. pseudotuberculosis. Serum haptoglobin concentration was measured using a hemoglobin-binding assay and plasma fibrinogen concentration by refractometry following heat precipitation. Total leukocyte counts were determined using a hemocytometer, and differential leukocyte counts were performed on smears of peripheral blood. RESULTS: Twenty-one sheep were seropositive at the start of the study; 15 became seropositive during the study. Only 2 sheep were seronegative at the conclusion of the study. Haptoglobin and fibrinogen concentrations and WBC counts were not significantly different for seropositive and seronegative animals. Nine sheep, 5 that were seropositive positive at the start and 4 that became seropositive during the study period, developed abscesses in peripheral lymph nodes. There were 15 animals that became seropositive during the study, and their values did not differ significantly among the 3 phases--seronegative, acute (IgM+/IgG±), and chronic (IgM-/IgG+)--of infection. However, 11 of these sheep did not develop peripheral abscesses and had significantly higher haptoglobin concentrations and lower monocyte counts during the acute phase of the disease than did the 4 sheep that later developed abscesses. CONCLUSION: Serum haptoglobin concentration and monocyte counts may be potential markers for progression of CLA in sheep.