[Prevalence of Anaplasma marginale and specific antibodies in new born calves].

Anaplasma marginale is an intraerythrocytic rickettsia that affects the cattle and constitute a constraint for its production. The transplacental transmission of A. marginale could be of importance under field conditions, but until now no data is available to interpret its relevance in Venezuela. The goal of this work was to evaluate both the presence of A. marginale and the antibody response against the rickettsia in new born calves. Fourteen calves, one week old, were simultaneously bled for parasitological tests, packed cell volume measurement and to obtain sera for immunoenzymatic assays. All the animals showed parasitemia between seventeen and thirty days old. The antibody IgM and IgG response at this time was low. Probably, these calves acquired A. marginale infection through transplacental route and a very low level of immunity by the colostrum.