Avaliação da leucometria na identificação da leucose enzoótica dos bovinos em rebanhos do estado de Pernambuco

Abstract

The Enzootic Bovine Leukosis (EBL) is a threat to the health of cattle herds in the state of Pernambuco and improvement in the use of epidemiological tools to identify and eliminate outbreaks of the disease demands attention. The aim of this study was to evaluate the leukocyte count as an aid in the identification of outbreaks of EBL and sanitation of livestock, from tests performed to establish the prevalence of this insidious retrovirus and Bovine Tuberculosis (BT) in cattle raised in several cities in the state. Were submitted for the EBL´s serodiagnosis 1000 bovine samples originating from 33 herds, 920 of them being previously submitted to the tuberculin test. Approximately 70% (694/1000) of the bovine leukocyte counts were analyzed, and disregarded animals with inconclusive results to two diagnostic tests and the positive to the tuberculin test. Thus, 530 samples were divided into two experimental groups, according to the results of AGID: GI = white blood cell count of 379 seronegative cattle, and IGI = white blood cell count of 151 seropositive cattle. The prevalence of EBL and BT were 28% (282/1000) and 11% (99/920), respectively. Overall, the mean values of leukocytes were: total = 12.0 ± 4.7 and lymphocytes = 8.1 ± 5.4 (x103/mm3). Considering the experimental groups, the mean values of leukocytes in GI (total = 11.5 ± 3.8 and = 7.6 ± 5.1 lymphocytes x103/mm3) were significantly lower (p <0.05) than those of GII (total = 13.3 ± 6.3 and = 9.1 ± 5.9 lymphocytes x103/mm3). 30% (159/530) of cattle examined had leukocytosis due to lymphocytosis - LL (total leukocytes and lymphocytes larger than x103/mm3 12.1 and 8.4, respectively), with the higher frequency of GI animals (99/379) with this lymphoproliferative disorder than GII (60/151), however the average values of GII leukocyte (total = 18.6 ± 6.5 and lymphocytes = 14.0 ± 6.7 x103/mm3) were significantly higher (p <0.05) to GI (total = 15.9 ± 3.1 and lymphocytes = 12.1 ± 8.0 x103/mm3). Analyzing the cattle with LL and that had leukocyte values above the reference standard deviation (total = 15.0 = 12.7 x103/mm3 and lymphocytes, respectively), there wasn´t significant difference between GI (total = 19 , 9 = ± 3.5 and 15.8 ± 3.9 lymphocytes x103/mm3) and GII (total = 23.2 ± 7.4 and 19.2 ± 7.4 lymphocytes = x103/mm3). Cattle GI (seronegative) with LL (total> 15.0 and lymphocytes> 12.7 x103/mm3) were considered suspect because leukocyte counts did not differ significantly with those of GII (seropositive) with LL. It is concluded that with the VLB demonstration of interference in leukocyte counts of cattle examined and the identification of suspect cattle not detected by AGID, the leukocyte count lends itself as an auxiliary to the identification of outbreaks of LEB and sanitation of livesto