Detection of Anaplasma marginale DNA in larvae of Boophilus microplus ticks by polymerase chain reaction.

Boophilus microplus larvae from two different sources were used for the detection of Anaplasma marginale DNA: larvae A, which were collected from a pasture of an endemic farm, and larvae B, which originated from engorged female ticks fed on calves with no clinical signs of disease and with low rickettsemia (approximately 0.01 to 1.0%).