Endemic (murine) typhus in returned travelers from Asia, a case series: clues to early diagnosis and comparison with dengue

Murine Typhus: A Review of a Reemerging Flea-Borne Rickettsiosis with Potential for Neurologic Manifestations and Sequalae

Murine typhus is an acute febrile illness caused by Rickettsia typhi, an obligately intracellular Gram-negative coccobacillus. Rats (Rattus species) and their fleas (Xenopsylla cheopis) serve as the reservoir and vector of R. typhi, respectively. Humans become infected when R. typhi-infected flea feces are rubbed into flea bite wounds or onto mucous membranes. The disease is endemic throughout much of the world, especially in tropical and subtropical seaboard regions where rats are common. Murine typhus is reemerging as an important cause of febrile illness in Texas and Southern California, where an alternate transmission cycle likely involves opossums (Didelphis virginiana) and cat fleas (Ctenocephalides felis). Although primarily an undifferentiated febrile illness, a range of neurologic manifestations may occur, especially when treatment is delayed. Serology is the mainstay of diagnostic testing, but confirmation usually requires demonstrating seroconversion or a fourfold increase in antibody titer from acute- and convalescent-phase sera (antibodies are seldom detectable in the first week of illness). Thus, early empiric treatment with doxycycline, the drug of choice, is imperative. The purpose of this review is to highlight murine typhus as an important emerging and reemerging infectious disease, review its neurologic manifestations, and discuss areas in need of further study.

Comprehensive Travel Health Education for Tour Guides: Protocol for an Exploratory Sequential Mixed Methods Research

Background

Tourists are at risk of experiencing health problems during their travel. However, even though tour guides have the potential to become travel health promoters, their participation has not been optimal.

Objective

This study aims to develop a comprehensive travel health education model to help tour guides improve health information delivery to tourists.

Methods

This is an exploratory sequential mixed methods research. The first phase consisted of a qualitative study with an informed grounded theory design. In-depth interviews were carried out with tour guides from all language divisions and policymakers of the Indonesian Tour Guide Association Bali Branch or Himpunan Pramuwisata Indonesia Daerah Bali (HPI Bali). The interview guidelines were developed based on the theory of planned behavior and identity theory. Qualitative data were analyzed thematically. In the interim phase, a travel health education model and questionnaire were developed based on the qualitative findings. The initial model and its instruments were finetuned after consultation with travel medicine and health promotion experts. Furthermore, the validity and reliability of the questionnaire were tested on 30 tour guides. The second phase consisted of a quantitative study with a randomized pretest-posttest control group design. A total of 76 tour guides in the intervention group received comprehensive travel health education, while 76 in the control group received no specific intervention. Outcome variables (ie, attitudes, subjective norms, perceived behavioral control, actual behavioral control, role identity, and behavioral intention) were measured at baseline (T0), after the online training (T1), before information sharing via WhatsApp (T2), a month after the start of the WhatsApp intervention (T3), and at the end of the WhatsApp intervention (T4). The mean difference of each outcome variable before and after the intervention will be compared between the intervention and control groups. Thereafter, the quantitative and qualitative findings will be integrated into a joint display.

Results

The qualitative phase was conducted through in-depth interviews with 21 informants who included tour guides and policymakers from HPI Bali from May to June 2021. The education model, educational materials, and questionnaire were developed based on the qualitative findings and consultation with experts. The education model consists of online training and information sharing through WhatsApp and was trialed with tour guides from November 2021 to February 2022. As of April 2022, this study is in the quantitative data analysis stage.

Conclusions

A travel health education model was developed based on qualitative findings and consultation with experts. The model was tested with tour guides, and a series of self-administered questionnaires were completed. This study is in the quantitative data analysis stage and will continue by integrating qualitative and quantitative findings into a joint display.

Trial Registration

ClinicalTrials.gov NCT04961983; https://clinicaltrials.gov/ct2/show/NCT04961983

Rickettsiosis in Southeast Asia: Summary for International Travellers during the COVID-19 Pandemic

Rickettsiosis is an important cause of febrile illness among travellers visiting Southeast Asia (SEA). The true incidence of rickettsiosis is underestimated; however, murine typhus and scrub typhus are widely distributed across SEA. Among travellers visiting SEA, scrub typhus was mostly reported from Thailand, whereas murine typhus was frequently found in Indonesia. Although most cases are self-limited or present with mild symptoms, a few cases with severe clinical manifestations have been reported. Doxycycline remains the key treatment of rickettsiosis. Some travellers, such as backpackers, trekkers, or cave explorers, are at a higher risk for rickettsiosis than others. Therefore, in resource-limited conditions, empirical treatment should be considered in these travellers. The coronavirus disease 2019 (COVID-19) pandemic has contributed to difficulty in the diagnosis of rickettsiosis because of the clinical similarities between these diseases. In addition, physical distancing mandated by COVID-19 management guidelines limits accurate physical examination, resulting in misdiagnosis and delayed treatment of rickettsiosis. This review summarises the characteristics of murine typhus and scrub typhus, describes travel-associated rickettsiosis, and discusses the impact of the COVID-19 pandemic on rickettsiosis.

Rickettsioses as Major Etiologies of Unrecognized Acute Febrile Illness, Sabah, East Malaysia

Orientia tsutsugamushi, spotted fever group rickettsioses, and typhus group rickettsioses (TGR) are reemerging causes of acute febrile illness (AFI) in Southeast Asia. To further delineate extent, we enrolled patients >4 weeks of age with nonmalarial AFI in Sabah, Malaysia, during 2013-2015. We confirmed rickettsioses (past or acute, IgG titer >160) in 126/354 (36%) patients. We confirmed acute rickettsioses (paired 4-fold IgG titer rise to >160) in 38/145 (26%) patients: 23 O. tsutsugamushi, 9 spotted fever group, 4 TGR, 1 O. tsutsugamushi/spotted fever group, and 1 O. tsutsugamushi/TGR. PCR results were positive in 11/319 (3%) patients. Confirmed rickettsioses were more common in male adults; agricultural/plantation work and recent forest exposure were risk factors. Dizziness and acute hearing loss but not eschars were reported more often with acute rickettsioses. Only 2 patients were treated with doxycycline. Acute rickettsioses are common (>26%), underrecognized, and untreated etiologies of AFI in East Malaysia; empirical doxycycline treatment should be considered.

The Rickettsioses: A Practical Update

Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness throughout the world. Rickettsioses present as an acute undifferentiated febrile illness and are often accompanied by headache, myalgias, and malaise. Cutaneous manifestations include rash and eschar, which both occur at varying incidence depending on the infecting species. Serology is the mainstay of diagnosis, and the indirect immunofluorescence assay is the test of choice. Reactive antibodies are seldom present during early illness, so testing should be performed on both acute-phase and convalescent-phase sera. Doxycycline is the treatment of choice.

Spectrum of illness among returned Australian travellers from Bali, Indonesia: a 5-year retrospective observational study

BACKGROUND

Bali, Indonesia, presents significant infectious and non-infectious health risks for Australian travellers. Understanding this spectrum of illnesses has the potential to assist clinicians in evaluating unwell returning travellers and guide provision of pre-travel advice.

AIM

To describe the spectrum of illnesses seen in returned travellers from Bali.

METHODS

Using a novel text mining approach, we performed a retrospective, observational study of all adult emergency department presentations to a metropolitan health service in Melbourne, from 2011 to 2015. Outcome measures included demographic, clinical and laboratory features of travel-related illnesses.

RESULTS

A total of 464 patients met inclusion criteria. Gastroenteritis (119/464, 26%), systemic febrile illness (88/464, 19%) and respiratory tract infection (51/464, 11%) were the most common diagnoses. Dengue was the most common laboratory-confirmed diagnosis (25/464, 5%). No cases of malaria were identified. Common non-infectious presentations included traumatic injury (47/464, 10%) and animal bites requiring rabies post-exposure prophylaxis (29/464, 6%). A total of 110 patients (24%) was admitted to the hospital; those presenting with systemic febrile illness were more likely to be admitted compared to those presenting with other illnesses (odds ratio 3.42, 95% confidence interval 2.02-5.75, P < 0.001).

CONCLUSION

This is the first study to use a text mining approach to identify and describe emergency department presentations related to diseases acquired in Bali by Australian travellers. Although infections are important causes of illness, trauma and animal bites account for a significant number of hospital presentations. Our findings contribute to the knowledge on the health risks for travellers to Bali, and will assist clinicians in relevant pre- and post-travel evaluations.

A Prospective, Open-label, Randomized Trial of Doxycycline Versus Azithromycin for the Treatment of Uncomplicated Murine Typhus

BACKGROUND

Murine typhus, or infection with Rickettsia typhi, is a global but neglected disease without randomized clinical trials to guide antibiotic therapy.

METHODS

A prospective, open, randomized trial was conducted in nonpregnant, consenting inpatient adults with rapid diagnostic test evidence of uncomplicated murine typhus at 2 hospitals in Vientiane, Laos. Patients were randomized to 7 days (D7) or 3 days (D3) of oral doxycycline or 3 days of oral azithromycin (A3). Primary outcome measures were fever clearance time and frequencies of treatment failure and relapse.

RESULTS

Between 2004 and 2009, the study enrolled 216 patients (72 per arm); 158 (73.2%) had serology/polymerase chain reaction (PCR)-confirmed murine typhus, and 52 (24.1%) were R. typhi PCR positive. The risk of treatment failure was greater for regimen A3 (22.5%; 16 of 71 patients) than for D3 (4.2%; 3 of 71) or D7 (1.4%; 1 of 71) (P < .001). Among R. typhi PCR-positive patients, the area under the time-temperature curve and the fever clearance time were significantly higher for A3 than for D3 (1.8- and 1.9-fold higher, respectively; P = .005) and D7 (1.5- and 1.6-fold higher; P = .02). No patients returned with PCR-confirmed R. typhi relapse.

CONCLUSION

In Lao adults, azithromycin is inferior to doxycycline as oral therapy for uncomplicated murine typhus. For doxycycline, 3- and 7-day regimens have similar efficacy. Azithromycin use in murine typhus should be reconsidered. Investigation of genomic and phenotypic markers of R. typhi azithromycin resistance is needed.

CLINICAL TRIAL REGISTRATION

ISRCTN47812566.

Misdiagnosed murine typhus in a patient with multiple cerebral infarctions and hemorrhage: a case report

Background

Rickettsias cause a wide spectrum of tick-, flea-, or mite-borne infections. Rickettsial infections have no classical manifestations and can often lead to encephalitis, which can be fatal if improperly diagnosed.

Case presentation

A 74-year-old male farmer was admitted to the hospital with fevers and a headache that had lasted for 10 days, followed by 4 days of unconsciousness, and his condition continued to deteriorate. Images showed multiple acute lesions in the brain stem, and bilateral cerebral and cerebellar hemispheres. He was finally diagnosed with endemic typhus and treated with antibiotics that resulted in improvement.

Conclusion

The present report describes a patient with a rickettsial infection and subsequent deterioration to coma because of an initial misdiagnosis. Because of the similarity to other infectious diseases, physicians should be more vigilant towards the history and radiologic results to ensure early detection and avoid complications which may prove to be fatal.

Rickettsioses and Q fever in travelers (2004-2013)

Rickettsioses (also called typhus) are associated with arthropods, including ticks, mites, fleas, and lice, although Q fever is more frequently acquired through the inhalation of contaminated aerosols or the consumption of milk. These zoonoses first emerged in the field of travel medicine 20 years ago. Here, we review rickettsioses and Q fever in travelers, highlighting cases reported in the past decade. African tick bite fever and Mediterranean spotted fever are the two most frequent spotted fevers. While the presentation of these fevers is typically benign, cardiac and neurological complications due to African tick bite fever have been reported, and Mediterranean spotted fever has been complicated by multi-organ failure and death in a few cases. Murine typhus and Q fever remain difficult to recognize and diagnose because these illnesses often present with only fever. New molecular tools, particularly when deployed with samples obtained from eschar swabs, might be easily implemented in laboratories with PCR facilities. Doxycycline must be introduced upon clinical suspicion of rickettsioses or Q fever and should be considered in cases of fever of unknown origin in travelers who are returning from at-risk geographic areas.

Rickettsial infections in Southeast Asia: implications for local populace and febrile returned travelers

Rickettsial infections represent a major cause of non-malarial febrile illnesses among the residents of Southeast Asia and returned travelers from that region. There are several challenges in recognition, diagnosis, and management of rickettsioses endemic to Southeast Asia. This review focuses on the prevalent rickettsial infections, namely, murine typhus (Rickettsia typhi), scrub typhus (Orientia tsutsugamushi), and members of spotted fever group rickettsiae. Information on epidemiology and regional variance in the prevalence of rickettsial infections is analyzed. Clinical characteristics of main groups of rickettsioses, unusual presentations, and common pitfalls in diagnosis are further discussed. In particular, relevant epidemiologic and clinical aspects on emerging spotted fever group rickettsiae in the region, such as Rickettsia honei, R. felis, R. japonica, and R. helvetica, are presented. Furthermore, challenges in laboratory diagnosis and management aspects of rickettsial infections unique to Southeast Asia are discussed, and data on emerging resistance to antimicrobial drugs and treatment/prevention options are also reviewed.