A FOCUS OF TICK-BORNE RELAPSING FEVER IN SOUTHERN ZAIRE

Relapsing fevers occur worldwide and are characterized by recurrent ep isodes of fever and spirochetemia. In central, eastern, and southern A frica, the disease is often caused by Borrelia duttonii, which is tran smitted by the soft tick Ornithodoros moubata. We conducted a field in vestigation in September 1994 at a hospital in Mitwaba, southern Zaire , which was the only medical facility within 150 km. The introduction of a rapid blood-smear staining technique allowed us to demonstrate th at 4.3%-7.4% of the 25-50 new outpatients seen each day had relapsing fever. Because of the absence of malaria in this area, these patients account for most of the febrile patients. The incidence of relapsing f ever among all pregnant women in the maternity ward was estimated to b e 6.4%, and this condition often led to maternal death or to spontaneo us abortion. The 16S rRNA gene of B. dutonii was sequenced after the s pirochete was isolated from patients' blood samples and directly from Ornithodoros tick vectors. In this region of Africa, relapsing fever s hould now be considered an important public health priority.