DEMONSTRATION OF A CARRIER STATE FOR COWDRIA-RUMINANTIUM IN WILD RUMINANTS FROM AFRICA

Four wild African ruminants, eland (Taurotragus oryx), giraffe (Giraff a camelopardalis), kudu (Tragephalus strepsiceros strepsiceros), and b lue wildebeest (Connochaetes taurinus), were experimentally infected w ith the rickettsia Cowdria ruminantium, the tickborne agent causing he artwater in domestic ruminants. The infections were established, and C . ruminantium was transmitted to naive small ruminants by the vector A mblyomma hebraeum when transmission attempts were made at days 128 (el and and wildebeest), 85 (giraffe), and 24 (kudu) post infection. These wild ruminants, which are natural hosts for the tick vector, and whic h commonly occur within heartwater-endemic areas of Africa, are likely to play important roles in the epidemiology of heartwater as reservoi rs of C. ruminantium infection. These findings also demonstrate that c onsiderable risks are associated with the translocation of wild rumina nts from heartwater-endemic areas to heartwater-free areas such as the northern and southern American mainlands, which have large population s of susceptible domestic and wild ruminant hosts and tick species tha t are capable of transmitting the disease.