Scrub typhus in pregnancy: A 10-year multicenter study in resource-limited settings in China.

Background: Despite its association with high mortality rates and negative fetal outcomes, large-scale epidemiological studies on scrub typhus (ST) during pregnancy remain scarce.

Methods: We conducted a retrospective, multicenter study by collecting 260 pregnant women with ST in China across a 10-year time period to evaluate how clinical characteristics changed over this time and identify risk factors for poor fetal outcome.

Results: In total, 78.5% (n = 204) presented with pathognomonic eschars or ulcers, and 75.4% (n = 196) had Weil-Felix test, in which 46.4% (n = 91) had a titer of ≥1:160 for OXK. A higher proportion of patients with pneumonia (18.7% vs. 9.5%, p = 0.033) and a longer length of hospitalization (7 vs. 6 days, p = 0.007) were seen in laboratory confirmed cases than clinically diagnosed cases. Compared to patients in the second trimester, a higher miscarriage rate (64.5% vs. 15.0%, p < 0.001) was observed in the first trimester, and a lower fetal death/stillbirth rate (1.0% vs 18.7%, p < 0.001) and a higher prematurity rate (21.0% vs. 9.3%, p = 0.019) were observed in the third trimester. The use of chloramphenicol (5.7% vs. 15.5%, p = 0.016) and fetal death/stillbirth rate (3.1% vs. 12.8%, p = 0.01) were decreased, but there was no significant improvement in fetal outcome in the second 5 years (35.1% vs. 39.7%, p = 0.466). Over 1/3 (n = 90) had a poor fetal outcome, including 40.0% (n = 36) miscarriage, 23.3% (n = 21) fetal death/stillbirth and 36.7% (n = 33) preterm birth. The use of macrolides reduced the risk of a poor fetal outcome, while lower gestational age (GA) at the time of infection, pneumonia, leucopoenia, thrombocytopenia, and use of chloramphenicol were associated with a poor fetal outcome in univariate logistic-regression analysis, but only lower GA at the time of infection and pneumonia were independent risk factors for a poor fetal outcome on multivariate logistic-regression analysis with an odds ratio of 6.6 (95% CI 2.4-17.8, p < 0.001) and 3.1 (95% CI 1.3-7.6, p = 0.011).

Conclusions: This is the largest number of cases of ST in pregnancy so far. Our findings indicate that this population have a high risk of poor fetal outcome, especially those with lower GA at the time of infection and those with pneumonia at the same time. Further studies are needed to investigate the correlation between antibiotics regimens for this population and fetal outcome.