Resumo O presente estudo relata a diversidade genética de Anaplasma marginale durante surtos de anaplasmose bovina no Brasil em propriedades localizadas nos Estados de Goiás e São Paulo. No rebanho bovino de Mambaí, Estado de Goiás, Centro-oeste do Brasil, observaram-se taxas de mortalidade de 3,5% (37/1050) nos bezerros; 4,7% (45/954) nas novilhas e 1,1% (25/2200) nas vacas em lactação. No rebanho bovino de Lins, Estado de São Paulo, Sudeste do Brasil, embora os animais tenham apresentado sinais clínicos sugestivos de anaplasmose bovina, culminando em redução drástica da produção leiteira, nenhum animal veio a óbito. Assim, amostras de sangue de 100 bovinos com sinais clínicos sugestivos de anaplasmose foram coletadas em Mambaí-GO e Lins-SP. Baseando-se na estrutura do microssatélite da MSP1a de A. marginale, observou-se a presença dos genótipos E e H em Lins e C, D e E em Mambaí. A análise da estrutura em “tandem repeats” da MSP1a mostrou nove diferentes estirpes (τ-10 -15, α-β2, α-β3-13, α-β2 192, τ-β-100, α-β2-Γ, 193-β-100, 191-13-Γ e 191-13-18) em Lins e duas (α-β3-Γ e E-F-φ2-F2) em Mambaí. Três novos “tandem repeats” da MSP1a (191, 192 e 193) foram descritos. Foi observado predomínio das estirpes τ-10-15 e α-β3-Γ associado à ocorrência de anaplasmose clínica e mortalidade em bezerras, novilhas e vacas em lactação.

Abstract The present study reports the genetic diversity of Anaplasma marginale during anaplasmosis outbreaks in rural properties of the states of Goiás and São Paulo, Brazil. Mortality rates of 3.5% (37/1,050) in calves, 4.7% (45/954) in heifers and 1.1% (25/2,200) in lactating cows were observed in a cattle herd of the municipality of Mambaí, state of Goiás, central-western Brazil. In a cattle herd from the municipality of Lins, state of São Paulo, in southeastern Brazil, none of the animals died, despite presenting clinical signs suggestive of bovine anaplasmosis and exhibiting a drastic decrease in milk production. Thus, blood samples were collected from 100 animals with clinical signs suggestive of bovine anaplasmosis in the municipalities of Mambaí and Lins. Based on the microsatellite structure of the MSP1a of A. marginale, the genotypes E and H were observed in Lins, and the C, D and E genotypes were found in Mambaí. The analysis of the tandem repeat structures of the MSP1a showed nine different strains (τ-10 -15, α-β2, α-β3-13, α-β2 192, τ-β-100, α-β2-Γ, 193-β-100, 191-13-Γ and 191-13-18) in Lins and two (α-β3-Γ and E-F-φ2-F2) in Mambaí. Three new tandem repeats of MSP1a (191, 192 and 193) were described. The τ-10-15 and α-β3-Γ strains were predominantly associated with the occurrence of clinical anaplasmosis and mortality in calves, heifers and lactating cows.

Anaplasma marginale is a Rickettsia infecting mature erythrocytes of cattle, causing great economic losses in tropical and subtropical regions. The disease is characterized by a marked hemolytic anemia, weight loss, abortion and sometimes death. Animals, which recover from the acute phase of the disease, stay persistently infected and become reservoir for transmission to healthy animals. There is a need of more sensitive diagnostic techniques to be used in the international movement of livestock towards disease free areas, which allow the detection of carrier animals, as well as to determine the prevalence of the disease in tropical and subtropical regions. For anaplasmosis diagnostic, different techniques are used, among them, agent detection, Giemsa staining to blood smears, inoculation of splenectomized animals, which is the gold standard for diagnosing the disease and the molecular diagnostic methods, which are currently used for the international movement of livestock, because of their sensitivity and specificity. For the detection of antibodies, a complement fixation has been extensively used since a few decades. Card agglutination, indirect immunofluorescence and ELISA tests are the most commonly used for the detection of antibodies, but many of these techniques use crude antigens, contaminated with erythrocyte membranes, which results in a high number of false negatives when persistently infected animals are analyzed. Recent advances and development of new diagnostic methodologies can provide great benefits in improving the diagnostic of this entity. This study discusses the trends existing in the diagnostic of Anaplasma marginale.

Anaplasma marginale es una Rickettsia que parasita los eritrocitos maduros del ganado bovino, provocando grandes pérdidas económicas en las regiones tropicales y subtropicales. La enfermedad se caracteriza por marcada anemia hemolítica, disminución del peso, aborto y en ocasiones la muerte. Los animales que logran recuperarse de la fase aguda de la enfermedad permanecen persistentemente infectados y se convierten en reservorio para la transmisión de la misma a los animales sanos, por lo que se hace necesario poder contar con técnicas de diagnóstico más sensibles para ser utilizadas en el movimiento internacional de ganado hacia zonas libres de la enfermedad, que permitan la detección de animales portadores, así como para conocer la prevalencia de la enfermedad en las regiones tropicales y subtropicales. Para el diagnóstico de la anaplasmosis se utilizan diferentes técnicas, dentro de las que se incluyen para la detección del agente, la tinción con Giemsa a los frotis sanguíneos; la inoculación de animales esplenectomizados, que constituye el estándar de oro del diagnóstico de la enfermedad y los métodos de diagnóstico molecular, los cuales se utilizan en la actualidad para el movimiento internacional de ganado, debido a su sensibilidad y especificidad. Para la detección de anticuerpos, la fijación del complemento fue muy utilizada hasta hace unas décadas. La aglutinación en tarjeta, la inmunofluorescencia indirecta y las pruebas ELISA son las más utilizadas para la detección de anticuerpos, pero muchas de estas técnicas utilizan antígenos crudos, contaminados con membranas del eritrocito, lo que da como resultado un número elevado de falsos negativos cuando se analizan animales persistentemente infectados. Los avances recientes y el desarrollo de nuevas metodologías de diagnóstico pueden proporcionar grandes ventajas en la mejora en el diagnóstico de esta entidad. En el presente trabajo se expone las tendencias que existen en el diagnóstico de Anaplasma marginale.