Tick-Borne Relapsing Fever in Rural Tanzania; from a Poverty Related Disease to Travelers Disease

Background: Tick-Borne Relapsing Fever (TBRF) was once a major world-wide epidemic disease and was an endemic disease like malaria in Sengerema district, close to Lake Victoria, Tanzania. Our aim was to study the incidence and fatality of TBRF over the past 60 years. Methods: From 1962 to 2015, we analyzed the annual reports, number of admissions, blood smears of patients with fever from Borrelia (TBRF) and malaria as controls. Furthermore, we studied the signs, symptoms and outcomes of TBRF in a prospective study during the peak incidence of TBRF, during the period 1985-1987. Results: The average number of annual admissions in Sengerema District Hospital due to TBRF was 40 in the sixties/seventies, 200 in the eighties (range from 4 in 1962 to 455 in 1988), dropping to 30 in the nineties. The common clinical features of the disease were: fever (93%), headaches (74%), muscleand joint pain (62%), splenomegaly (60%), and hepatomegaly (38%). Recently, over the past ten years no TBRF were recorded and no Borrelia spirochetes were found in blood smears. Discussion: During the last century, we witnessed the disappearance of TBRF in Sengerema, north Tanzania. The incidence of TBRF in Sengerema district was the highest during the eighties, when borders with Kenya were closed and the economy was down after the war with Uganda. The increase of gold mining, improvement of the local economy, with improvements of housing and standards of living after the nineties, resulted in a complete reduction of the incidences of TBRF.