A Systematic Review of Mortality from Untreated Scrub Typhus (Orientia tsutsugamushi)

Abstract

BackgroundScrub typhus, a bacterial infection caused by Orientia tsutsugamushi, is increasingly recognized as an important cause of fever in Asia, with an estimated one million infections occurring each year. Limited access to health care and the disease’s non-specific symptoms mean that many patients are undiagnosed and untreated, but the mortality from untreated scrub typhus is unknown. This review systematically summarizes the literature on the untreated mortality from scrub typhus and disease outcomes.Methodology/Principal FindingsA literature search was performed to identify patient series containing untreated patients. Patients were included if they were symptomatic and had a clinical or laboratory diagnosis of scrub typhus and excluded if they were treated with antibiotics. The primary outcome was mortality from untreated scrub typhus and secondary outcomes were total days of fever, clinical symptoms, and laboratory results. A total of 76 studies containing 89 patient series and 19,644 patients were included in the final analysis. The median mortality of all patient series was 6.0% with a wide range (min-max) of 0–70%. Many studies used clinical diagnosis alone and had incomplete data on secondary outcomes. Mortality varied by location and increased with age and in patients with myocarditis, delirium, pneumonitis, or signs of hemorrhage, but not according to sex or the presence of an eschar or meningitis. Duration of fever was shown to be long (median 14.4 days Range (9–19)).ConclusionsResults show that the untreated mortality from scrub typhus appears lower than previously reported estimates. More data are required to clarify mortality according to location and host factors, clinical syndromes including myocarditis and central nervous system disease, and in vulnerable mother-child populations. Increased surveillance and improved access to diagnostic tests are required to accurately estimate the untreated mortality of scrub typhus. This information would facilitate reliable quantification of DALYs and guide empirical treatment strategies.

Distinguishing Japanese Spotted Fever and Scrub Typhus, Central Japan, 2004– 2015

“…Of note, the clinical severity of ST may differ according to the Orientia serotype. According to a systematic review, the mortality rate from ST substantially varied according to patients’ age, co-occurring conditions, and regional Rickettsia strains ( 33 ). Our findings of ST in regions where Irie/Kawasaki type and Hirano/Kuroki type are endemic may not be directly applicable to other settings in which other serotypes are endemic, such as Akita and Niigata in northern Japan.…”

In Search of Scrub Typhus: A Prospective Analysis of Clinical and Epidemiological Profile of Patients from a Tertiary Care Hospital in New Delhi

“…The incidence of meningoencephalitis in other Indian studies ranged from 9.5% to 23.3% [6] [16] [22]. Even though cardiac myocyte is a known target of scrub typhus, very few cases of myocarditis in scrub typhus has been reported in literature [4]. We reported 5 cases of myocarditis in our study.…”

“…Around a million cases of scrub typhus are reported each year with an estimated mortality of around 6% in untreated patients [3] [4]. Scrub typhus is predominantly reported from an area commonly known as the "Tsutsugamushi triangle" that extends from east of Russia and Japan in the north to Australia in the south and Afghanistan in the west.…”

Scrub typhus: a case report

“…Other features such as cough (50%), abdominal pain (15%), vomiting (10%), epistaxis (6%) and seizures (<5%) were not so common. 5 A characteristic papule may be seen at the site of bite which evolves into a black eschar. Though it is considered diagnostic but it may be seen only in 35% of cases.…”