ABSTRACT The present study explored the predictive values of milk leukocyte differentials (MLD) as a basis for improving the diagnosis of intramammary infections (IMIs) and subclinical mastitis. Quarter milk samples were collected for bacteriological analysis, quarter somatic cell count (qSCC), and MLD. The MLD were assessed using the cytospin technique, direct microscopic smears, and flow cytometry. The predictive values of each single leukocyte population and useful potential indices that could better reflect immune complexity were also calculated. Changes in the percentage of any leukocyte alone failed to substantially improve the predictive value of qSCC in diagnosing IMIs. Although certain parameters increased the area under the receiver operating characteristic curve (ROC curve) as a result of increased specificity values, a slight reduction in sensitivity was observed. The so-called CD8 complex was a unique parameter which improved both the sensitivity (78.79 %) and the specificity (80.77 %) in IMI diagnosis, resulting in the highest area under the ROC curve (0.87). To diagnose subclinical mastitis, the percentage of macrophages and the sum of the percentage PMNLs and T CD8+ cells divided by the percentage of macrophages showed the highest predictive values (sensitivity = 79.63, specificity = 73.68, and area under the ROC curve = 0.83) in the differentiation of the inflammatory condition status of cows. In conclusion, this study provides further insights into using T CD8+ lymphocytes in diagnosing bovine IMIs, combined with PMNLs and macrophages. The antidromic trend of macrophages vs. PMNLs and T CD8+ lymphocytes due to the increasing qSCCs was crucial to differentiating quarters under both inflammatory and non-inflammatory conditions. (MLD IMIs (IMIs mastitis analysis qSCC, , (qSCC) technique smears cytometry calculated observed socalled so called CD 78.79 7879 78 79 (78.7 % 80.77 8077 80 77 (80.7 0.87. 087 0.87 . 0 87 (0.87) 7963 63 79.63 7368 73 68 73.68 0.83 083 83 cows conclusion vs noninflammatory non conditions (qSCC 78.7 787 7 (78. 80.7 807 8 (80. 08 0.8 (0.87 796 6 79.6 736 73.6 78. (78 80. (80 0. (0.8 79. 73. (7 (8 (0. ( (0

RESUMO A brucelose bovina (BB) é uma bacteriose de notificação obrigatória, causada pela Brucella abortus, responsável por distúrbios reprodutivos graves em bovinos, prejuízos consideráveis ao comércio e agravos em saúde pública. Objetivaram-se com este estudo identificar a frequência de BB e analisar os fatores de risco nos rebanhos leiteiros da microrregião de Rio Branco, Acre. Assim, 527 amostras sorológicas de bovinos foram submetidas ao teste do antígeno acidificado tamponado e ao 2-mercaptoetanol. Os fatores de risco foram caracterizados por aplicação de questionários epidemiológicos. Utilizou-se o teste de regressão logística para avaliar a existência de associação significativa entre as variáveis. A frequência da BB na microrregião de Rio Branco foi de 10,6% (56/527). O destino inadequado do feto abortado e restos placentários (odds ratio — OR = 13,6), o abate de bovinos na propriedade (OR = 3,4) e a faixa etária acima de 4 anos (OR = 2,9) foram os fatores de risco mais significativos apontados pelo modelo de regressão logística. Conforme os resultados deste estudo, recomenda-se a intensificação nas medidas de controle e profilaxia da BB na microrregião de Rio Branco, sobretudo relacionadas ao manejo sanitário e reprodutivo nas criações.

ABSTRACT Bovine brucellosis (BB) is a compulsory notifiable bacterial disease caused by Brucella abortus, which is responsible for severe reproductive disorders in cattle, considerable damages to trade and public health damage. The objectives of this study were to identify the frequency of BB and to analyze the risk factors in the dairy herds of the Rio Branco microregion, in the state of Acre, Brazil. Thus, 527-bovine-serological samples were submitted to the buffered acidified antigen test and to 2-mercaptoethanol. Risk factors were characterized by the administration of epidemiological questionnaires. The logistic regression test was used to evaluate the existence of a significant association between the variables. The frequency of BB in the Rio Branco microregion was 10.6% (56/527). The inappropriate destination of the aborted fetus and placental remnants (odds ratio — OR = 13.6), the slaughter of cattle within the property (OR = 3.4) and the age range above 4 years old (OR = 2.9) were the most significant risk factors identified by the logistic regression model. According to the results of this study, it is recommended to intensify BB control and prophylaxis measures in the microregion of Rio Branco, especially those related to sanitary and reproductive management in the livestock breeding.