Association between handling stress in the corral and rabies antibody titers in selenium-supplemented cattle

This study determined the correlation between serum cortisol levels and rabies antibody titers in cattle primo-vaccinated against rabies and supplemented with dietary selenium (Se). Sixty Nelore male calves (10 to 12 months old) received daily and individual dietary supplementation with 0, 3.6, 5.4 and 6.4 mg Se (groups Gc, G3.6, G5.4 and G6.4, respectively). The animals were vaccinated against rabies (day 0) and subjected to handling stress in the corral for 120 days. Blood sampling procedures were performed on days 0, 15, 30, 60, 90 and 120. Cortisol levels increased until day 90, but had dropped significantly by day 120 (P < 0.01). Rabies antibody titers on days 30 and 90 were similar among Se-supplemented groups; in the control group, rabies antibodies decreased significantly from day 30 to 60, and 90 to 120. Serum cortisol levels and antibody titers were not correlated in most of the groups or blood sampling days. A positive correlation among these variables was found only in G6.4 on days 60 (R = 0.513; P = 0.05) and 120 (R = 0.644; P = 0.009). In conclusion, repeated handling in the corral stresses cattle, but without compromising rabies humoral immune response.

Chicken embryo related (CER) cell line for quantification of rabies neutralizing antibody by fluorescent focus inhibition test.

Levels of rabies virus neutralization antibody in sera from vaccinated dogs and cattle were either measured by mouse neutralization test (MNT) or by rapid fluorescent focus inhibition test (RFFIT), performed on CER monolayers. The two tests were compared for their ability to detect the 0.5 International Units/ml (I.U.) recommended by the World Health Organization (WHO) as the minimum response for proof of rabies immunization. A significant correlation was found between the two tests (n=211; r=0.9949 in dogs and 0.9307 in cows, p<0.001), good sensitivity (87.5%), specificity (94.7%) and agreement (96.6%) as well. RFFIT method standardized on CER cell system for neutralizing antibodies detection turns the diagnosis easier and less expensive, specially when a great number of samples must be tested from endemic areas as commonly found in Brazil.

Interval between first dose and booster affected antibody production in cattle vaccinated against rabies

In this study, we compared the levels of neutralizing antibodies induced by inactivated rabies vaccine in cattle by using three alternative immunization procedures. Forty-five bovines (breed nelore) were then organized in three groups (A, B and C, with 15 animals/group). Group A received only one vaccine dose at day zero and Group B received the first dose at day zero and then another dose at day 30 (early booster). Group C was also immunized with two doses; however, the booster was postponed until day 180 after the first dose (delayed booster). Blood samples were withdrawn at days zero (before the first dose) and 30, 210, 390, and 540 after the beginning of immunization and the antibody titers were evaluated by mouse neutralization test. The protocol used to immunize Group C (booster at day 180) was clearly more efficient. In this group, antibody levels were higher and also remained higher for longer periods in comparison with the other two groups. These results show that booster timing significantly affected antibody levels. Therefore, programs addressed to control this disease in cattle should consider not only the use of a booster but also its administration time

[Prophylaxis of infective complications of central venous catheters]. / Profilaxis de las complicaciones infecciosas de los catéteres venosos centrales.

Infections related to central venous cannulation present first-magnitude problems in recovery rooms and intensive care units. Catheter-related bloodstream infection (CRBSI) is the most serious complication because of its high frequency and a mortality rate that averages around 3%. Although infections arise for various reasons, point-of-insertion contamination is the main cause when catheters are implanted for periods of less than 10 days. Contaminating microorganisms (especially Staphyloccocus epidermidis) find refuge from the host's defenses in a biofilm that covers the catheter. Several factors participate in the formation of this biofilm, such as catheter composition, proteins of the host or type of microorganism. Biofilm bacteria are resistant to both antibiotics and the host's own defenses (e.g. phagocytes and antibodies). The microorganism can then begin to reproduce, possibly leading to bloodstream infection. The measures designed to prevent this process include recommendations for both catheter insertion and maintenance. Recent meta-analyses have led to certain conclusions but no unanimity among authors. Thus, there is agreement on the adoption of strict aseptic technique during catheter insertion, on the use of chlorhexidine as a skin antiseptic and on choice of the subclavian vein. Such measures significantly decrease the frequency of CRBSI. Maintenance techniques that have been shown to be effective are the use of connectors impregnated with antiseptic, catheters impregnated with antiseptics or antibiotics, and permeable dressings. Additionally, building an experienced infusion-therapy team to insert and maintain central venous catheters has been shown to be one of the most effective measures for preventing CRBSI.

Concentration of lead in mineral salt mixtures used as supplements in cattle food.

We measured lead concentrations in samples of mineral salt mixtures used in cattle feed in the states of Paraná and São Paulo, Brazil. Lead content was determined spectrometrically by the atomic plasma induction method. Of the 30 samples analyzed, 9 had lead concentrations above 30 ppm (range 35.7 to 284.5 ppm) which is the maximum concentration recommended by the National Research Council (NRC 1980). These findings show the necessity for careful industrial monitoring because some mineral mixtures contain sufficient lead to cause toxicity.

Effect of a booster-dose of rabies vaccine on the duration of virus neutralizing antibody titers in bovines.

Humoral immune response using inactivated rabies vaccine was studied in 35 nelore cross-bred bovines of western region of São Paulo state. Ninety days after vaccination, 13 (92.8%) animals presented titers > or = 0.5 IU/ml, through mouse neutralization test. After 180 days, 9 (64.3%) sera showed titers > or = 0.5 IU/ml, after 270 days, only one (7.1%) showed a titer of 0.51 IU/ml, and after 360 days, all animals showed titers < 0.5 IU/ml. Group of animals receiving booster dose 30 days after vaccination presented, two months after, all with titers > 0.5 IU/ml. At 180 days, 17 (80.9%) sera presented titers > 0.5 IU/ml; at 270 days, 15 (71.4%), with titers > or = 0.5 IU/ml and at 360 days, 4 (19.0%), with titers > or = 0.5 IU/ml. Booster-dose ensured high levels of neutralizing antibodies for at least three months, and 240 days after revaccination, 71.4% of animals were found with titers > or = 0.5 IU/ml.