High prevalence of Anaplasma marginale in the Crioula Lageana cattle

Introduction: Bovine anaplasmosis is caused by the bacterium Anaplasma marginale; its transmission occurs through vectors such as ticks. Crioula Lageana is a native cattle breed from the South of Brazil used for beef production, with excellent meat quality. There are no studies of the epidemiology of this disease in Crioula Lageana even though tick damage is known to be frequent. Methodology: Blood samples were collected from 311 Crioula Lageana cattle and subjected to DNA extraction and polymerase chain reaction (PCR) using specific primers for the Major Surface Protein 5 (msp5) gene for the detection of the bovine anaplasmosis agent. The animals were classified according to the gender, the category and the presence or absence of ticks at the time of collection. The animal owners completed an epidemiological questionnaire to determine factors that might be associated with anaplasma infection. Results: The prevalence of A. marginale was 79.9%. The following factors were found to be protective against infection: I) the breeding objectives (whether animals were destined for beef production and trade or solely for beef production), II) tick control rate; and III) pregnant and lactating cows and calves as the categories least affected by the hemoparasite. The main risk factor for hemoparasite acquisition was the use of organophosphates and avermectins as acaricides. Conclusions: Crioula Lageana cattle are in a situation of enzootic stability', with a high prevalence of A. marginale infection. The factors associated with the infection were: I) breeding objectives, II) tick control rate, III) the acaricides used, and IV) the most tick-parasitized categories of cattle.