A review of heartwater and the threat of introduction of Cowdria ruminantium and Amblyomma spp. ticks to the American mainland.

Heartwater, caused by the rickettsial agent Cowdria ruminantium, is one of the most devastating livestock diseases in sub-Saharan Africa. In addition to domestic cattle, sheep, and goats, a variety of nondomestic species can acquire subclinical and clinical infections. Recent epidemiologic findings that demonstrate a long-term host carrier state in domestic and wild ruminants, intrastadial transmission by the tick vectors (Amblyomma spp.), vertical transmission of the agent from cows to their calves, and the presence of both C. ruminantium and Amblyomma variegatum in the Caribbean suggest that the introduction of this exotic disease to the American mainland is a significant threat. Veterinarians working with wildlife should be familiar with this disease and should follow appropriate preventive measures to minimize the risk of infection in captive and wild populations of ruminants.