Objective: To assess the impact of tick-borne relapsing fever (TBRF) on the outcome of pregnancy.
Design: Case control study of 137 pregnant women (cases) and 120 non-pregnant women (controls) with TBRF between 1985 and 1995.
Setting: A rural hospital in Tabora Region, Tanzania.
Results: 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.
Conclusions: 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.
PIP: The impact of tick-borne relapsing fever (TBRF) on pregnancy outcome was investigated in a case-control study of 137 pregnant women and 120 non-pregnant women infected with this condition and treated at a rural hospital in Tanzania's Tabora region during 1985-95. The risk of premature delivery during TBRF was 58%, with a perinatal mortality of 436 per 1000 births. Total pregnancy loss, including abortions, was 475 per 1000. The case-fatality rate was 1.5% in pregnant women compared with 1.7% in non-pregnant controls. The relapse rate was 3.6% in pregnant women and 1.7% in controls. Pregnant women with TBRF had higher densities of spirochetes than controls, and the risk of delivery during an attack was significantly correlated with increasing spirochete density and gestational age. Perinatal mortality was associated with low birth weight and low gestational age, but not with the degree of spirochetemia. The increased spirochete densities in cases are presumed to reflect decreasing immunity during pregnancy. In view of the very high perinatal mortality associated with preterm delivery in TBRF-infected women, prevention and early management are crucial. Although house spraying with benzene hexachloride will temporarily prevent TBRF, permanent results can be achieved only through improved housing construction.