Clinical manifestations of scrub typhus

Imported scrub typhus in Europe: Report of three cases and a literature review

BACKGROUND

Scrub typhus is a vector-borne rickettsial infection, which can cause relevant morbidity and mortality. While the number of cases is around a million per year globally, the infection is seldom diagnosed in travellers from Europe.

METHODS

We herein report three cases diagnosed in Italian travellers and review the literature about imported cases in Europe in the last 60 years.

RESULTS

Three participants to the same hiking trip to the forest of northern Laos presented fever and other symptoms, including eschars (2 individuals) and skin rash (2 individuals). Overall, they didn't report complications, and recovered soon after doxycycline treatment. Diagnosis was retrospectively confirmed with PCR in one of them. The review collected data from 40 patients. Almost all of them (95%) presented fever, more than a half had headache, skin rash, eschars, arthromyalgias. 73% of them were hospitalized, and 16.2% needed intensive care. Diagnosis was confirmed by serology in almost all cases (94.6%). Most patients (88%) were treated with doxycycline. All patients survived, although one case resulted in incomplete tetraparesis.

CONCLUSIONS

Scrub typhus should be considered in all travellers coming back from endemic areas and presenting with acute febrile illness. Laboratory diagnosis can be challenging, as specific tests are not widely available. In case of clinical suspicion, a prompt treatment with oral doxycycline could avoid severe complications.

Genome-Wide Association Study Identifies Eight Novel Loci for Susceptibility of Scrub Typhus and Highlights Immune-Related Signaling Pathways in Its Pathogenesis

Scrub typhus is a fatal zoonotic disease caused by Orientia tsutsugamushi. This disease is accompanied by systemic vasculitis, lymphadenopathy, headache, myalgia, and eschar. In recent studies, a novel strain that is resistant to current medical treatment was identified in Thailand. Thus, the development of new specific drugs for scrub typhus is needed. However, the exact molecular mechanism governing the progression of scrub typhus has not been fully elucidated. To understand disease-related genetic factors and mechanisms associated with the progression of scrub typhus, we performed a genome-wide association study (GWAS) in scrub typhus-infected patients and found a scrub typhus-related signaling pathway by molecular interaction search tool (MIST) and PANTHER. We identified eight potent scrub typhus-related single nucleotide polymorphisms (SNPs) located on the PRMT6, PLGLB2, DTWD2, BATF, JDP2, ONECUT1, WDR72, KLK, MAP3K7, and TGFBR2 genes using a GWAS. We also identified 224 genes by analyzing protein-protein interactions among candidate genes of scrub typhus and identified 15 signaling pathways associated with over 10 genes by classifying these genes according to signaling pathways. The signaling pathway with the largest number of associated genes was the gonadotropin-releasing hormone receptor pathway, followed by the TGF-beta signaling pathway and the apoptosis signaling pathway. To the best of our knowledge, this report describes the first GWAS in scrub typhus.

Prolonged coma in scrub typhus: consider non-convulsive status epilepticus

BACKGROUND

Scrub typhus is prevalent in the Tsutsugamushi belt and may manifest with meningoencephalitis and seizures. We report a patient with scrub typhus who had non-convulsive status epilepticus (NCSE).

METHODS

A 50-y-old female with fever and altered sensorium for 5 d was diagnosed as scrub typhus based on serum IgM ELISA. She was on mechanical ventilation and received doxycycline and ceftriaxone, but did not improve until the third day of admission.

RESULTS

An EEG revealed >2.5 Hz generalised epileptiform discharges, which were suppressed by intravenous lorazepam suggesting NCSE. Following valproate and levetiracetam, she became conscious and had a full recovery.

CONCLUSION

A scrub typhus patient recovers even after prolonged NCSE.

Scrub typhus mimicking the clinical course of infectious mononucleosis: a case report

Objective: Scrub typhus is a relatively common life-threating disease; its symptoms are non-specific and similar to those of other viral infections. Therefore, scrub typhus might be underdiagnosed.

Patient: Herein, we report a patient with scrub typhus whose clinical course mimicked that of infectious mononucleosis. A 63-year-old male patient with hypertension presented to our hospital complaining of symptoms including prolonged fever, pharyngeal discomfort, and a mild headache. He showed the appearance of a rash after amoxicillin administration. At the same time, he did not show a crusted rash on his body surface.

Results: After a comprehensive examination, Epstein-Barr virus and cytomegalovirus infections were ruled out. We suspected that this patient suffered from scrub typhus on the basis of his usual lifestyle. Finally, polymerase chain reaction analysis showed a positive result for deoxyribonucleic acid of Orientia tsutsugamushi in his blood sample. Fortunately, he recovered naturally with only supportive treatment during his hospitalization.

Conclusion: We should observe and monitor patients with infectious mononucleosis-like symptoms and emphasize the importance of a clinical interview.

Diagnostic Utility of Procalcitonin in Scrub Typhus

Background:

Procalcitonin (PCT) and C-reactive protein (CRP) are two common and practical biomarkers for various diseases. However, their roles in scrub typhus (ST) have not been extensively investigated.

Aim:

In this study, we compared the effectiveness of PCT and CRP levels and the PCT/CRP ratio and evaluated their predictive performance in the diagnosis of ST.

Methods:

Patients with acute febrile illness and suspected ST infection treated at our hospital between January 2015 and December 2016 were retrospectively evaluated. An indirect immunofluorescent assay was used to confirm the presence of ST. Documented information included initial clinical images and laboratory data including PCT or CRP. Receiver operating characteristic curve analysis with area under curve (AUC) identified the optimal PCT, CRP, and PCT/CRP ratio cutoff values for the diagnosis of ST.

Results:

Among 189 patients with acute febrile illness, 153 (89.9%) tested positive for ST. CRP and PCT level data were available in 168 (88.8%) and 42 (22.2%) patients, respectively. Thirty patients (15.9%) underwent both CRP and PCT tests. ST-positive samples contained significantly higher levels of PCT (P < 0.001) and CRP (P = 0.015) than those of the 36 non-ST samples. No difference was observed in the PCT/CRP ratio (P = 0.477). The optimal cutoff values were 0.27 ng/mL, 1.65 mg/dL and 0.036 for PCT and CRP levels and PCT/CRP ratio, respectively. PCT level showed the best diagnostic performance (sensitivity = 89.3%; specificity = 92.3%; AUC = 0.894; 95% confidence interval [CI] =0.753–0.925). Combining PCT and CRP levels based on the respective optimal cutoff points further improved the performance of ST diagnosis (AUC = 0.906, 95% CI = 0.894–0.923), with 89.5% sensitivity and 91.7% specificity. PCT level was positively correlated with liver enzyme levels, and acute hepatitis could be identified with high specificity (100%) using a cutoff PCT threshold of 0.36 ng/mL.

Conclusion:

PCT is useful in ST diagnosis, and pending conformation in future studies may reflect hepatic dysfunction at initial presentation.

Scrub Typhus and Other Rickettsial Infections

Scrub typhus and other rickettsial infections contribute to 25 - 50% of acute undifferentiated febrile illnesses in endemic regions. Delayed recognition and therapy increase the morbidity and mortality. The constellation of fever with eschar or rash and multisystem involvement should facilitate the diagnosis and initiation of appropriate therapy. The pathological hallmark of rickettsial infections is endothelial infection and inflammation causing vasculitis. Endothelial inflammation results in microvascular dysfunction and increased vascular permeability. Immune and endothelial activation may worsen microvascular dysfunction, predisposing to multi-organ failure. Serology is the mainstay of diagnosis, although false negatives occur early in the disease. Point-of-care rapid diagnostic tests and molecular techniques, such as quantitative polymerase chain reaction (qPCR), can hasten diagnostic processes. Intravenous doxycycline with a loading dose is the most widely used antibiotic in critically ill patients, with azithromycin as a suitable alternative. Early appropriate treatment and organ support can decrease the duration of illness and be life-saving. How to cite this article: Gunasekaran K, Bal D, Varghese GM, et al. Scrub Typhus and Other Rickettsial Infections. Indian J Crit Care Med 2021;25(Suppl 2):S138-S143.

Analysis of 262 Children with Scrub Typhus Infection: A Single-Center Experience

Scrub typhus, a vector-borne rickettsiosis, is the leading treatable cause of non-malarial febrile illness in Asia. The myriad of typical and atypical features poses a clinical conundrum. We aimed to study the clinical and laboratory profile of children with scrub typhus infection diagnosed by IgM ELISA. Data of children < 12 years presenting with undifferentiated fever to the pediatric services of a tertiary teaching institute between January 2012 and December 2018 were retrieved. Children with seropositive IgM ELISA (InBios International Kit) for scrub typhus were enrolled in the study. Clinical features, laboratory investigations, treatment received, and the outcome recorded were obtained. Objective evidence of organ dysfunction was taken as severe scrub typhus. In total, 262 children were diagnosed with scrub typhus. The mean age was 5 years, with male preponderance (65%). And, 13 children presented during infancy. Fever was universal, and generalized lymphadenopathy (93.5%) and hepatomegaly (70%) were the common clinical signs. Eschar was identified in 31%, with greater predilection for groin and axilla. Thrombocytopenia was striking in one-third of children. Also, 25 children (9.5%) had severe scrub typhus and 18 required intensive care stay. Elevated aspartate aminotransferase enzyme levels was a predictor of severity ([OR 3.9], P value 0.005) by multivariate analysis. Lymphadenopathy was found significantly associated with eschar (P < 0.005). No mortality was recorded. This 6-year study underscores the varied spectrum of pediatric scrub typhus infection. Zero mortality in our cohort signifies the excellent outcome with judicious first-line antibiotics.

Rickettsioses in Children - A Review

Rickettsial diseases, caused by a variety of obligate intracellular, Gram-negative bacteria from the genera Rickettsia, Orientia, Ehrlichia, Neorickettsia, Neoehrlichia, and Anaplasma are considered some of the most covert emerging and re-emerging diseases. Scrub typhus, murine flea-borne typhus and Indian tick typhus are commonly being reported and during the last decade. Scrub typhus (ST) has emerged as a serious public health problem in India. Rickettsial infections are generally incapacitating and difficult to diagnose; untreated cases have case fatality rates as high as 30-45% with multiple organ dysfunction, if the specific treatment is delayed. Early clinical suspicion, timely diagnosis followed by institution of specific antimicrobial therapy shortens the course of the disease, lowers the risk of complications and reduces morbidity and mortality due to rickettsial diseases. Still there is large gap in our knowledge of Rickettsioses and the vast variability and non-specific presentation of these have often made it difficult to diagnose clinically. The present review describes the epidemiology, clinical manifestations, diagnostic modalities and treatment of Scrub typhus which is a vastly underdiagnosed entity and clinicians should suspect and test for the disease more often.

Diagnosis of scrub typhus: recent advancements and challenges

Scrub typhus is a mite-borne, acute febrile illness caused by the bacterium Orientia tsutsugamushi. It is a re-emerging infectious disease of the tsutsugamushi triangle. Scrub typhus is transmitted through bites of contaminated chiggers (larval stage). Diagnosis of scrub typhus is challenging as its symptoms mimic with other acute febrile illnesses. Several methods are effectual for diagnosis of scrub typhus that includes enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), Weil-Felix, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). Weil-Felix test was initially used for the diagnosis of scrub typhus in underdeveloped countries but not preferred due to a lack of both specificity and sensitivity. Other immuno-based methods like IFA and ELISA are most outrank for detection of scrub typhus due to their higher sensitivity and specificity, but not vigorous to lay bare the infection at early stages and need the convalescent sampling for verification of positive samples. On another deed, PCR based methods becoming acceptable over era due to its dexterity of early-stage diagnosis with higher specificity and sensitivity but lack its applicability in circumstances of scrub typhus due to the variegated genetic makeup of Orientia tsutsugamushi among its serotypes. The present review focused on various detection methods along with their advantages and disadvantages used in the diagnosis of scrub typhus. A comparison between available methods of diagnosis with challenges in the detection of scrub typhus is also summarized.

Efficacy and Safety of Antibiotics for Treatment of Scrub Typhus: A Network Meta-analysis

Importance

Antibiotics have been used for many years to treat scrub typhus, but their efficacy and safety have not been studied thoroughly.

Objective

To compare and rank different antibiotics to identify which one can safely eliminate Orientia tsutsugamushi and efficiently alleviate fever in patients with scrub typhus.

Data Sources

An electronic search of PubMed and Embase was conducted, from database inception to July 12, 2019. The study was conducted from July 12 to September 2, 2019.

Study Selection

Randomized clinical trials and retrospective studies that evaluated the use of antibiotics for treatment in patients diagnosed with scrub typhus caused by O tsutsugamushi were included. Records of articles in English were considered eligible. Studies were assessed independently by 2 reviewers, with disagreement resolved by consensus. Of 6408 studies initially identified, 10 randomized clinical trials and 4 retrospective study met the criteria for further analysis.

Data Extraction and Synthesis

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension statement for systematic reviews incorporating network meta-analyses of health care interventions. Data were independently extracted by 2 reviewers and synthesized with frequentist random-effects network meta-analyses.

Main Outcomes and Measures

The primary outcome was efficacy of the antibiotic, considered as the number of patients who achieved complete healing with an antibiotic. Safety, defined as the prevalence of adverse events associated with the antibiotics, was the secondary outcome, and defervescence time was the tertiary outcome. P scores (scale of 0 to 1, with 1 indicating superiority to other treatments) were used to rank the efficacy, safety, and defeverescence time of the antibiotics.

Results

Three searches for articles in Embase and PubMed identified 10 randomized clinical trials (888 participants) and 4 retrospective studies (323 participants) for further analyses. No particular treatment regimen showed a significant advantage or disadvantage with regard to efficacy or safety. However, meta-analysis of retrospective studies indicated that clarithromycin (P score = 0.8730) alleviated fever more efficiently than other antibiotics.

Conclusions and Relevance

No treatment regimen reported in this network meta-analysis showed a significant advantage or disadvantage with regard to efficacy or safety. However, clarithromycin might be a better choice than the other drugs for alleviating fever.

Scrub typhus as a rare cause of acute pyelonephritis: case report

BACKGROUND

Scrub typhus can present with atypical signs and symptoms such as those of acute kidney injury, gastroenteritis, pneumonitis, and acute respiratory distress syndrome. Meningitis, encephalitis, and hepatic dysfunction have also been reported, particularly in severe cases with multisystem involvement. Scrub typhus has never been reported in the literature to cause urinary tract infections (UTIs) which includes cystitis and pyelonephritis.

CASE PRESENTATION

A 45-year old male presenting to the outpatient unit with fever, right flank pain, and burning micturition for three days was initially treated for UTI. However, he returned to the hospital on the fourth day of illness with persistent symptoms. He was hospitalized, with intravenous (IV) ceftriaxone. Computerized tomography scan of his abdomen-pelvis showed features of acute pyelonephritis, so his antibiotics were upgraded to meropenem and teicoplanin. Despite this, the patient's condition deteriorated. Laboratory investigations showed multisystem involvement: decreasing platelets, raised creatinine, and deranged liver panel. As Kathmandu was hit by dengue epidemic during the patient's hospitalization, on the seventh day of his illness, blood samples were sent for tropical fever investigation. All tests came out negative except for scrub typhus-IgM antibodies positive on rapid diagnostic test. The patient's symptoms subsided after 48 h of starting doxycycline and he became fully asymptomatic four days later. Fever did not recur even after discontinuing other IV antibiotics, favoring scrub typhus disease rather than systemic bacterial sepsis.

CONCLUSIONS

Scrub typhus is an emerging infectious disease of Nepal. Therefore, every unexplained fever cases (irrespective of clinical presentation) should be evaluated for potential Rickettsiosis. Moreover, for cases with acute pyelonephritis, atypical causative agents should be investigated, for example scrub typhus in this case.

Sequelae Following Acute Encephalitis Syndrome Caused by Orientia Tsutsugamushi

We evaluated 146 patients with acute encephalitis syndrome caused by Orientia tsutsugamushi, after median interval of 5 months of hospitalization, to estimate the proportion and spectrum of disability. Fifty-six (38.4%) had mild, whereas 19 (13%) had moderate to severe degree of disability. Most patients had impairment in the domain of cognition and behavior.

Complex Cytokine Responses in Imported Scrub Typhus Cases, Germany, 2010-2018

Scrub typhus is a life-threatening zoonotic disease, which is caused by Orientia tsutsugamushi, an obligatory intracellular Gram-negative bacterium. It is transmitted by Leptotrombidium mites in endemic regions of Southeast Asia. So far, data on imported scrub typhus cases to non-endemic areas and immunological descriptions are rare. Eleven scrub typhus cases that had been diagnosed by the German National Reference Center for Tropical Pathogens between 2010 and 2018 were retrospectively reviewed for clinical symptoms, laboratory changes, and travel destinations. Patient sera were included if follow-up samples showed simultaneous seroconversion for IgM and IgG antibody responses by immunofluorescence assays or concurrence with the first serum sample. The median of seroconversion was week 2 after symptom onset. Cytokine levels were measured over time, demonstrating simultaneously upregulated major Th1, Th2, and Th17 cytokines in the acute phase of infection followed by normalization during convalescence. This study underlines the complex mixed cytokine response elicited by scrub typhus and highlights clinical and diagnostic aspects of imported infections with O. tsutsugamushi.

The estimated burden of scrub typhus in Thailand from national surveillance data (2003-2018)

BACKGROUND

Scrub typhus is a major cause of acute febrile illness in the tropics and is endemic over large areas of the Asia Pacific region. The national and global burden of scrub typhus remains unclear due to limited data and difficulties surrounding diagnosis.

METHODOLOGY/PRINCIPAL FINDINGS

Scrub typhus reporting data from 2003-2018 were collected from the Thai national disease surveillance system. Additional information including the district, sub-district and village of residence, population, geographical, meteorological and satellite imagery data were also collected for Chiangrai, the province with the highest number of reported cases from 2003-2018. From 2003-2018, 103,345 cases of scrub typhus were reported with the number of reported cases increasing substantially over the observed period. There were more men than women, with agricultural workers the main occupational group affected. The majority of cases occurred in the 15-64 year old age group (72,144/99,543, 72%). Disease burden was greatest in the northern region, accounting for 53% of the total reported cases per year (mean). In the northern region, five provinces-Chiangrai, Chiangmai, Tak, Nan and Mae Hong Son-accounted for 84% (46,927/55,872) of the total cases from the northern region or 45% (46,927/103,345) of cases nationally. The majority of cases occurred from June to November but seasonality was less marked in the southern region. In Chiangrai province, elevation, rainfall, temperature, population size, habitat complexity and diversity of land cover contributed to scrub typhus incidence.

INTERPRETATION

The burden of scrub typhus in Thailand is high with disease incidence rising significantly over the last two decades. However, disease burden is not uniform with northern provinces particularly affected. Agricultural activity along with geographical, meteorological and land cover factors are likely to contribute to disease incidence. Our report, along with existing epidemiological data, suggests that scrub typhus is the most clinically important rickettsial disease globally.

Scrub Typhus: Historic Perspective and Current Status of the Worldwide Presence of Orientia Species

Scrub typhus and its etiological agents, Orientia species, have been around for a very long time. Historical reference to the rickettsial disease scrub typhus was first described in China (313 AD) by Hong Ge in a clinical manual (Zhouhofang) and in Japan (1810 AD) when Hakuju Hashimoto described tsutsuga, a noxious harmful disease in the Niigata prefecture. Other clinicians and scientists in Indonesia, Philippines, Taiwan, Australia, Vietnam, Malaysia, and India reported on diseases most likely to have been scrub typhus in the early 1900s. All of these initial reports about scrub typhus were from an area later designated as the Tsutsugamushi Triangle-an area encompassing Pakistan to the northwest, Japan to the northeast and northern Australia to the south. It was not until the 21st century that endemic scrub typhus occurring outside of the Tsutsugamushi Triangle was considered acceptable. This report describes the early history of scrub typhus, its distribution in and outside the Tsutsugamushi Triangle, and current knowledge of the causative agents, Orientia species.

Rickettsia felis identified in two fatal cases of acute meningoencephalitis

BACKGROUND

Rickettsia felis has recently emerged worldwide as a cause of human illness. Typically causing mild, undifferentiated fever, it has been implicated in several cases of non-fatal neurological disease in Mexico and Sweden. Its distribution and pathogenicity in Southeast Asia is poorly understood.

METHODOLOGY/PRINCIPAL FINDINGS

We retroactively tested cerebrospinal fluid (CSF) or sera from 64 adult patients admitted to hospital in North Sulawesi, Indonesia with acute neurological disease. Rickettsia felis DNA was identified in the CSF of two fatal cases of meningoencephalitis using multi-locus sequence typing semi-nested PCR followed by Sanger sequencing. DNA from both cases had 100% sequence homologies to the R. felis reference strain URRWXCal2 for the 17-kDa and ompB genes, and 99.91% to gltA.

CONCLUSION/SIGNIFICANCE

The identification of R. felis in the CSF of two fatal cases of meningoencephalitis in Indonesia suggests the distribution and pathogenicity of this emerging vector-borne bacteria might be greater than generally recognized. Typically Rickettsia are susceptible to the tetracyclines and greater knowledge of R. felis endemicity in Indonesia should lead to better management of some acute neurological cases.

Scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia: a case report and review of the literature

BACKGROUND

Scrub typhus is an acute infectious zoonotic disease caused by Orientia tsutsugamushi. Multi-organ dysfunction secondary to scrub typhus is hard to diagnose and has a high mortality rate. Only one case of scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia has been reported thus far. In this study, we report a second case of scrub typhus with multi-organ dysfunction syndrome and immune thrombocytopenia, and we summarize its diagnosis and treatment.

CASE PRESENTATION

A 43-year-old Han Chinese woman, a sanitation worker, was admitted to our hospital after 7 days of a skin infection and 5 days of a sore throat with fever and dizziness. A physical examination revealed the presence of an eschar on the right side of her neck. She had a history of insect bites during her sanitation work. A diagnostic evaluation identified scrub typhus as the primary illness, which was associated with multi-organ dysfunction syndrome and immune thrombocytopenia. She recovered completely after 15 days of treatment and extensive symptomatic supportive care.

CONCLUSION

We report a second case of tsutsugamushi disease with multi-organ dysfunction syndrome and immune thrombocytopenia, which resolved after treatment and extensive care.

Re-emergence of scrub typhus in Zhejiang Province, southern China: A 45-year population-based surveillance study

BACKGROUND

Scrub typhus is the leading cause of treatable unidentified febrile illnesses in Southeast Asia. This study was conducted to document the epidemiological characteristics of scrub typhus and its change in Zhejiang, one of traditional epidemic provinces in China.

METHODS

Scrub typhus surveillance data in Zhejiang province during 1957-1989 and 2006-2012 were obtained. Descriptive analysis was conducted to characterize the epidemiology of scrub typhus. The spatial distributions over the periods were explored using spatial autocorrelation analysis and spatiotemporal cluster analysis.

RESULTS

A total of 4104 cases and 7 deaths were reported from 1957 to 1989 and 2006 to 2017. The incidence declined since 1959, remained low from 1967 to 1989, and then exponentially increased after 2006. The seasonality changed from a summer pattern between 1957 and 1989 to a bimodal peak pattern in July to August and October to November from 2006 to 2017. One primary and three secondary high-risk clusters were affirmed in both periods from 1980 to 1989 and 2006 to 2017. The primary cluster expanded southwestward and the time span of the secondary clusters extended in the later period compared to the clusters in the previous time frame.

CONCLUSION

Zhejiang recently underwent a seasonality change, geographic extension, and incidence increase in scrub typhus. More attention should be paid to controlling scrub typhus.

Serologic Evidence for Orientia Exposure in the Democratic Republic of Sao Tome and Principe

Orientia tsutsugamushi is an obligate intracellular bacterium that causes scrub typhus in humans. Formerly thought to be confined to the "tsutsugamushi triangle" within the Asia-Pacific region, scrub typhus was recently identified in the Western Hemisphere. Moreover, a new species of Orientia bacterial genus was isolated from a patient in Dubai. This study investigated Orientia exposure in an African country, the Democratic Republic of Sao Tome and Principe. Two sets of samples were analyzed in the study: 240 dried blood spots (DBSs) collected in 2016 and 863 serum samples from 570 pregnant women in 2003. Antibodies against O. tsutsugamushi were examined by immunofluorescence assay (IFA) and enzyme-linked immunosorbent assay (ELISA). The positive samples were further confirmed by Western blot. The results of IFA showed that 5.8% (14/240) of DBSs and 20.4% (116/570) of the serum samples contained reactive antibodies, whereas IgG ELISA yielded a positive rate of 15.4% (88/570) for the serum samples. These findings provided serologic evidence of potential Orientia exposure even though case of scrub typhus has never been diagnosed in the nation. Further studies are needed to determine the epidemiology and the burden of this neglected tropical disease in Africa.

Case Report: Acute pyelonephritis and hearing loss in scrub typhus

Acute pyelonephritis is a common renal manifestation in patients with diabetes. A 52-year-old diabetic lady presented with loin pain, dysuria, and fever and urinary incontinence that had begun seven and three days prior to presentation respectively. She was treated with escalating spectra of intravenous antibiotics without improvement. Urine and blood cultures were sterile, while radiological investigations were suggestive of pyelonephritis. Mild hepatic dysfunction prompted consideration of scrub typhus and she improved with empirical doxycycline. Scrub IgM was later confirmed to be positive. In conclusion, local prevalence of systemic infections such as rickettsioses should always be considered in diabetics with fever, even if symptoms and signs otherwise suggest typical diabetes-related infections. We, therefore report a case of acute pyelonephritis caused by scrub typhus which has not been previously described in English medical literature.

Development of multiplex PCR for neglected infectious diseases

Scrub typhus, murine typhus, and leptospirosis are widely neglected infectious diseases caused by Orientia tsutsugamushi, Rickettsia typhi, and pathogenic Leptospira spp., respectively. Patients usually present with non-specific symptoms and therefore are commonly diagnosed with acute undifferentiated febrile illness. Consequently, patients face delayed treatment and increased mortality. Antibody-based serological test currently used as gold standard has limitations due to insufficient antibody titers, especially in the early phase of infection. In this study, we aimed to develop multiplex PCR to combine 3 primer pairs that target specific genes encoding 56-kDa TSA of O. tsutsugamushi, 17-kDa antigen of R. typhi, and LipL32 of L. Interrogans and evaluate its performance in comparison to the standard serological tests. Using EDTA blood samples of known patients, the sensitivity and specificity of our multiplex PCR was 100% and 70%, respectively. In addition, the assay was able to diagnose the co-infection of scrub typhus and leptospirosis. The assay may be useful in identifying causative agents during the early phase of these diseases, enabling prompt and appropriate treatment.

Scrub typhus, murine typhus, and leptospirosis are diagnosed as acute undifferentiated febrile illness. Diagnostic tests for these diseases depend on antibody detection. However, antibody detection is still limited by its tendency to return negative results during the early phase of aforementioned diseases. In this study, a novel multiplex PCR has been developed for detecting Orientia tsutsugamushi, Rickettsia typhi, and Leptospira interrogans that are simultaneously amplified in a single tube. The results have shown that multiplex PCR could be used as a diagnostic tool for detecting bacteria during the early phase of scrub typhus, murine typhus, and leptospirosis, allowing for administration of appropriate treatment.

Acute Severe Calculous Cholecystitis with Multiorgan Failure Complicated by Scrub Typhus

Scrub typhus is a febrile illness and can present with manifestations ranging from subclinical symptoms to multiorgan failure and death. Scrub typhus is a rare etiology of acute cholecystitis. A patient presenting with the features of acute cholecystitis who does not respond to standard treatment should be screened for scrub typhus in a typhus endemic region. We report a case of a 70-year-old female with acute severe calculous cholecystitis with multiorgan failure complicated by scrub typhus. She improved remarkably after starting doxycycline for scrub typhus. Scrub typhus should be considered as a trigger in a patient presenting with cholecystitis in a typhus endemic region.

Under-diagnosis of rickettsial disease in clinical practice: A systematic review

BACKGROUND

Rickettsial diseases present as acute febrile illnesses, sometimes with inoculation eschars.

METHODS

We performed a systematic review of studies published between 1997 and 2017 to assess the underestimation of non-eschar rickettsial disease (NERD) relative to eschar rickettsial disease (ERD), as a cause of acute fever in patients with rickettsial diseases that commonly present with eschar(s): scrub typhus (ST), Mediterranean spotted fever (MSF), and African tick-bite fever. We compared ERD/NERD ratios according to study design: 'complete approach' studies, with testing performed in all patients with 'unspecified febrile illness'; versus 'clinical judgement' studies, with testing performed if patients presented with specific symptoms.

RESULTS

In 'complete approach' studies, ERD/NERD ratios were significantly lower, suggesting a considerable under-diagnosis of NERD in 'clinical judgement' studies. Based on these results, we estimate that the diagnosis of rickettsial disease was missed in 66.5% of patients with ST, and in 57.9% of patients with MSF.

CONCLUSIONS

Study design influences the reported eschar rates in ST and MSF significantly. NERD is likely to be a vastly underdiagnosed entity, and clinicians should consider and test for the disease more often.

PROSPERO REGISTRATION NUMBER

CRD 42016053348.

Scrub typhus (Tsutsugamushi disease) in a patient presenting with hemophagocytic syndrome

Scrub typhus is a mite-borne infectious disease caused by Orientia tsutsugamushi, which is found mainly in East and Southeast Asia and in Australia. The disease presents with a variety of non-specific symptoms, including fever, headache, cough, myalgia, and rash. Delay in starting appropriate antimicrobial therapy may lead to serious complications and even death. We report the case of an 84-year-old Japanese patient with scrub typhus who developed hemophagocytic syndrome (HPS) and was successfully treated with minocycline in addition to corticosteroids. A pathognomonic skin ulcer on her right buttock, which was initially covered with black eschar, prompted us to consider the possibility of scrub typhus. Blood polymerase chain reaction and antibody assays confirmed the diagnosis. Scrub typhus must be considered as one of the underlying diseases that may cause HPS in patients living in the Asia-Pacific region and in those who have recently returned from endemic areas.

An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection

The obligate intracellular bacterium Orientia tsutsugamushi is the causative agent of scrub typhus in humans, a serious mite-borne disease present in a widespread area of endemicity, which affects an estimated 1 million people every year. This disease may exhibit a broad range of presentations, ranging from asymptomatic to fatal conditions, with the latter being due to disseminated endothelial infection and organ injury. Unique characteristics of the biology and host-pathogen interactions of O. tsutsugamushi, including the high antigenic diversity among strains and the highly variable, short-lived memory responses developed by the host, underlie difficulties faced in the pursuit of an effective vaccine, which is an imperative need. Other factors that have hindered scientific progress relative to the infectious mechanisms of and the immune response triggered by this bacterium in vertebrate hosts include the limited number of mechanistic studies performed on animal models and the lack of genetic tools currently available for this pathogen. However, recent advances in animal model development are promising to improve our understanding of host-pathogen interactions. Here, we comprehensively discuss the recent advances in and future perspectives on host-pathogen interactions and the modulation of immune responses related to this reemerging disease, highlighting the role of animal models.