Tick-borne relapsing fever and pregnancy outcome in rural Tanzania

To assess the impact of tick-borne relapsing fever (TBRF) on the outcome of pregnancy.

Case control study of 137 pregnant women (cases) and 120 non-pregnant women (controls) with TBRF between 1985 and 1995.

A rural hospital in Tabora Region, Tanzania.

Risk of birth during the attack of TBRF was 58.0%, with an extremely high perinatal mortality of 436 per 1000 births. The total loss of pregnancies including abortions was 475. per 1000. Case-fatality rate in pregnant women was 1.5%, compared to 1.7% in the non-pregnant women. A Jarisch-Herxheimer reaction was seen in 1.5% of the cases and in 1.7% of controls. Relapse rate was 3.6%, compared to 1.7% in non-pregnant women. Pregnant women with TBRF show higher densities of spirochetes than non-pregnant women (p < 0.001). The risk of delivery during the attack was positively correlated to increasing density of the spirochetemia (p < 0.001) and to gestational age (p < 0.001). Perinatal death was related to low birthweight (p < 0.001) and low gestational age (p < 0.001) and not to degree of spirochetemia.

The extremely high perinatal mortality rate during an attack asks for prevention and early effective management of TBRF. This is a challenge where access to health services in rural areas of developing countries is hampered by many factors.