Scrub typhus infection in pregnancy: the dilemma of diagnosis and treatment in a resource-limited setting

Foetal outcome of Leptospira and Rickettsial infections during pregnancy: a systematic review

BACKGROUND

Leptospirosis and rickettsial infections are bacterial zoonoses prevalent in different geographical locations and presents with overlapping symptoms.

OBJECTIVE

To identify foetal outcomes in pregnant women diagnosed with rickettsial infections, including scrub typhus and leptospirosis, along with their associated factors.

METHODS

A comprehensive search was conducted in MEDLINE/PubMed, Scopus, CENTRAL (Cochrane), Web of Science, PsycINFO, Academic Search Premier, CINAHL, and Embase using defined search terms. Studies involving pregnant women with diagnosed leptospirosis and rickettsial infections, including scrub typhus, were selected. Two independent reviewers screened titles and abstracts using the Rayyan Web interface. Data extraction was performed in Microsoft Excel, with Zotero for reference management. Study quality was assessed using Joanna Briggs Institute Critical Appraisal tools. Data synthesis included narrative analysis.

RESULTS

Fifty-four studies were included: 22 on scrub typhus, 14 on rickettsial infection, 16 on leptospirosis, and 2 on all three infections. Of 176 scrub typhus cases, 53 resulted in foetal loss and 3 in neonatal death. Among 38 rickettsial infection cases, 4 had foetal loss. Out of 63 leptospirosis cases, 13 experienced foetal loss. Six maternal deaths occurred due to scrub typhus and one due to Rocky Mountain spotted fever.

CONCLUSION

Leptospirosis and rickettsial infections, including scrub typhus, are important causes of pregnancy loss. Further research is needed to better understand and mitigate these risks in pregnant women.

Doxycycline use and adverse pregnancy or neonatal outcomes: A descriptive study using the United States Food and Drug Administration Adverse Event Reporting System database

Background and Aims

Doxycycline is recommended for use in rickettsial diseases. The available evidence regarding its safety for rickettsial infection in pregnancy is limited. Our study aimed to describe the adverse events of doxycycline when used during pregnancy for any indication, in terms of adverse maternal and/or neonatal outcomes, using the United States Food and Drug Administration Adverse Event Reporting System (FAERS).

Methods

We used the OpenVigil software for extracting the safety reports from the United States submitted to the FAERS from 2004 to 2021. We manually reviewed reports of doxycycline use resulting in adverse pregnancy outcomes or congenital anomalies to describe the patient and safety event characteristics.

Results

From 2004 to 2021, 59 individual case safety reports containing preferred terms indicative of drug exposure during pregnancy or drug-induced adverse fetal outcomes were identified in the FAERS database. Following deduplication and manual review, 20 relevant adverse event reports were obtained. Doxycycline was the suspect medication in 13/20 (65%) reports. The common adverse event terms reported were premature delivery/baby in 6 reports, spontaneous abortion in 6, intrauterine death in 2, and various congenital anomalies in the rest. Fifty percent of the safety reports contained other medications which could have potentially caused the outcome.

Conclusions

The number of reported events in the FAERS database of adverse pregnancy/neonatal outcomes following doxycycline use is small, similar to the numbers reported from large cohort or surveillance studies. Given the presence of concomitant medications that could have contributed to the outcome, there does not seem to be a strong signal of harm, although this needs to be confirmed by surveillance studies.

Simple clinical and laboratory predictors to improve empirical treatment strategies in areas of high scrub typhus and dengue endemicity, central Vietnam

Background

Dengue fever is highly endemic in Vietnam, but scrub typhus—although recognized as an endemic disease—remains underappreciated. These diseases together are likely to account for more than half of the acute undifferentiated fever burden in Vietnam. Scrub typhus (ST) is a bacterial disease requiring antimicrobial treatment, while dengue fever (DF) is of viral etiology and does not. The access to adequate diagnostics and the current understanding of empirical treatment strategies for both illnesses remain limited. In this study we aimed to contribute to the clinical decision process in the management of these two important etiologies of febrile illness in Vietnam.

Methods

Using retrospective data from 221 PCR-confirmed scrub typhus cases and 387 NS1 protein positive dengue fever patients admitted to five hospitals in Khanh Hoa province (central Vietnam), we defined predictive characteristics for both diseases that support simple clinical decision making with potential to inform decision algorithms in future. We developed models to discriminate scrub typhus from dengue fever using multivariable logistic regression (M-LR) and classification and regression trees (CART). Regression trees were developed for the entire data set initially and pruned, based on cross-validation. Regression models were developed in a training data set involving 60% of the total sample and validated in the complementary subsample. Probability cut points for the distinction between scrub typhus and dengue fever were chosen to maximise the sum of sensitivity and specificity.

Results

Using M-LR, following seven predictors were identified, that reliably differentiate ST from DF; eschar, regional lymphadenopathy, an occupation in nature, increased days of fever on admission, increased neutrophil count, decreased ratio of neutrophils/lymphocytes, and age over 40. Sensitivity and specificity of predictions based on these seven factors reached 93.7% and 99.5%, respectively. When excluding the “eschar” variable, the values dropped to 76.3% and 92.3%, respectively.

The CART model generated one further variable; increased days of fever on admission, when eschar was included, the sensitivity and specificity was 95% and 96.9%, respectively. The model without eschar involved the following six variables; regional lymphadenopathy, increased days of fever on admission, increased neutrophil count, increased lymphocyte count, platelet count ≥ 47 G/L and age over 28 years as predictors of ST and provided a sensitivity of 77.4% and a specificity of 90.7%.

Conclusions

The generated algorithms contribute to differentiating scrub typhus from dengue fever using basic clinical and laboratory parameters, supporting clinical decision making in areas where dengue and scrub typhus are co-endemic in Vietnam.

Dengue fever is highly endemic in Vietnam, while scrub typhus is recognized as a re-emerging neglected disease. Both diseases are likely to account for more than half of the acute undifferentiated fever burden in Vietnam. However, scrub typhus is a bacterial disease requiring antimicrobial treatment, while dengue fever—of viral etiology—does not. Misdiagnosis and treatment delays cause potentially severe or fatal complications among scrub typhus patients, even though it is easily treatable. In this study, we used simple clinical and laboratory markers, which were identified upon admission of 221 PCR-confirmed scrub typhus cases and 387 NS1-positive dengue fever patients from Khanh Hoa province to identify the differences between scrub typhus and dengue. We found seven predictors that served to construct a simple clinical decision tree, holding great potential to distinguish scrub typhus from dengue using readily available clinical or laboratory findings. These predictors can strongly support medical staff in identifying scrub typhus cases from dengue, without using sophisticated diagnostic tests, and could improve the quality of diagnoses and appropriate treatment strategies at the primary health care level–especially in areas where scrub typhus and dengue fever are co-endemic in Vietnam and many parts of Asia and where diagnostic tests are not readily available.

Safety of Antimicrobials During Pregnancy: A Systematic Review of Antimicrobials Considered for Treatment and Postexposure Prophylaxis of Plague

BACKGROUND

The safety profile of antimicrobials used during pregnancy is one important consideration in the decision on how to treat and provide postexposure prophylaxis (PEP) for plague during pregnancy.

METHODS

We searched 5 scientific literature databases for primary sources on the safety of 9 antimicrobials considered for plague during pregnancy (amikacin, gentamicin, plazomicin, streptomycin, tobramycin, chloramphenicol, doxycycline, sulfadiazine, and trimethoprim-sulfamethoxazole [TMP-SMX]) and abstracted data on maternal, pregnancy, and fetal/neonatal outcomes.

RESULTS

Of 13 052 articles identified, 66 studies (case-control, case series, cohort, and randomized studies) and 96 case reports were included, totaling 27 751 prenatal exposures to amikacin (n = 9), gentamicin (n = 345), plazomicin (n = 0), streptomycin (n = 285), tobramycin (n = 43), chloramphenicol (n = 246), doxycycline (n = 2351), sulfadiazine (n = 870), and TMP-SMX (n = 23 602). Hearing or vestibular deficits were reported in 18/121 (15%) children and 17/109 (16%) pregnant women following prenatal streptomycin exposure. First trimester chloramphenicol exposure was associated with an elevated risk of an undescended testis (odds ratio [OR] 5.9, 95% confidence interval [CI] 1.2-28.7). Doxycycline was associated with cardiovascular malformations (OR 2.4, 95% CI 1.2-4.7) in 1 study and spontaneous abortion (OR 2.8, 95% CI 1.9-4.1) in a separate study. First trimester exposure to TMP-SMX was associated with increased risk of neural tube defects (pooled OR 2.5, 95% CI 1.4-4.3), spontaneous abortion (OR 3.5, 95% CI 2.3-5.6), preterm birth (OR 1.5, 95% CI 1.1-2.1), and small for gestational age (OR 1.6, 95% CI 1.2-2.2). No other statistically significant associations were reported.

CONCLUSIONS

For most antimicrobials reviewed, adverse maternal/fetal/neonatal outcomes were not observed consistently. Prenatal exposure to streptomycin and TMP-SMX was associated with select birth defects in some studies. Based on limited data, chloramphenicol and doxycycline may be associated with adverse pregnancy or neonatal outcomes; however, more data are needed to confirm these associations. Antimicrobials should be used for treatment and PEP of plague during pregnancy; the choice of antimicrobials may be influenced by these data as well as information about the risks of plague during pregnancy.

Scrub typhus: risks, diagnostic issues, and management challenges

Scrub typhus is an acute febrile illness in the “tsutsugamushi triangle”, transmitted by chiggers that can be treated effectively if detected early. Laboratory testing, including molecular and serological assays, is needed for confirming the diagnosis, especially in the absence of the pathognomonic eschar. In this review, factors that play a role in disease occurrence and clinical clues for diagnosis, in addition to risk factors contributing to disease severity, including mortality, are discussed in detail. Moreover, issues related to diagnostic assays, treatment, and mixed infections are also enumerated and described.