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ABSTRACT CONTEXT: Scrub typhus, caused by Orientia tsutsugamushi, has a wide range of clinical manifestations, including meningoencephalitis, acute renal failure, pneumonitis, myocarditis, and septic shock. However, there are no documented cases of scrub typhus with hypokalemia. In this report, we present a case of scrub typhus with hypokalemia and multiple organ failure syndrome, highlighting the importance of electrolyte imbalance in patients with scrub typhus. CASE REPORT: A 59-year-old woman presented to the emergency department with abdominal pain that had been present for 1 day. On admission, the physical examination and laboratory test results indicated that the patient had renal, liver, and circulatory failure, and hypokalemia. She developed meningitis and disseminated intravascular coagulation during hospitalization. She recovered with appropriate management, and was discharged on day 17. CONCLUSION: This report highlights the potential for atypical presentations of scrub typhus, including a previously undocumented association with hypokalemia. Although the contribution of hypokalemia to the patient's clinical course remains uncertain, this case underscores the importance of considering electrolyte imbalance in the management of patients with scrub typhus. Further research is warranted to better understand the relationship between scrub typhus and electrolyte imbalance.

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We assessed serum samples collected in Cauca Department, Colombia, from 486 persons for Orientia seroreactivity. Overall, 13.8% showed reactive IgG by indirect immunofluorescence antibody assay and ELISA. Of those samples, 30% (20/67) were confirmed to be positive by Western blot, showing >1 reactive band to Orientia 56-kD or 47-kD antigens.

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BACKGROUND & OBJECTIVES: Coexistence of tick-borne diseases in some regions in Latin America makes the diagnosis difficult due to shared initial signs and symptoms. Rickettsiosis, Lyme disease and recently, scrub typhus are gaining more importance. The objective of this study is to develop a multiplex-PCR assay for a differential diagnosis of rickettsiosis, Lyme disease and scrub typhus. METHODS: By using bibliographic and bioinformatic analysis, we identify candidate regions to perform the multiplex- PCR assay for Rickettsia sp., Borrelia burgdorferi and Orientia tsutsugamushi as well as identify optimal melting temperature and sensibility analysis. RESULTS: We identified specific primer pairs for Rickettsia sp, Borrelia burgdorferi and Orientia tsutsugamushi with different PCR fragment length but a common melting temperature, 58°C. INTERPRETATION & CONCLUSION: We successfully developed a Multiplex PCR assay for differential diagnosis of rickettsiosis, Lyme disease and scrub typhus that could be a rapid and easy option in clinical and epidemiological practice.

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The exposure of a research team to chigger mites in southern Chile allowed the first identification of a trombiculid species as vector and reservoir of scrub typhus outside the tsutsugamushi triangle, providing unique insights into the ecology and transmission of this recently discovered rickettsial infection in South America.

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The effect of climatological parameter on infectious disease is an interesting issue in clinical epidemiology. Of several parameters, rainfall is reported for its interrelationship with many tropical diseases such as malaria. In this short communication, the authors report the observation on correlation between rainfall and the prevalence of scrub typhus from a tropical endemic country.

El efecto del parámetro climatológico en las enfermedades infecciosas es un tema interesante en la epidemiología clínica. De varios parámetros, se reportan precipitaciones por su interrelación con muchas enfermedades tropicales como el paludismo. En esta breve comunicación, los autores informan de la observación sobre la correlación entre las precipitaciones y la prevalencia del tifus de matorral de un país endémico tropical.

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Scrub typhus is a potentially fatal rickettsiosis caused by Orientia species intracellular bacteria of the genus Orientia. Although considered to be restricted to the Asia Pacific region, scrub typhus has recently been discovered in southern Chile. We analyzed Orientia gene sequences of 16S rRNA (rrs) and 47-kDa (htrA) from 18 scrub typhus patients from Chile. Sequences were ≥99.7% identical among the samples for both amplified genes. Their diversity was 3.1%-3.5% for rrs and 11.2%-11.8% for htrA compared with O. tsusugamushi and 3.0% for rrs and 14.8% for htrA compared with Candidatus Orientia chuto. Phylogenetic analyses of both genes grouped the specimens from Chile in a different clade from other Orientia species. Our results indicate that Orientia isolates from Chile constitute a novel species, which, until they are cultivated and fully characterized, we propose to designate as Candidatus Orientia chiloensis, after the Chiloé Archipelago where the pathogen was identified.

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Endemic scrub typhus was recently detected on Chiloé Island in southern Chile. We report a series of cases, acquired over a wide geographical range in continental Chile during 2016-2018, demonstrating that this emerging rickettsial infection is also found on the mainland of South America.

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BACKGROUND: Scrub typhus is a neglected vector-borne zoonosis causing life-threatening illnesses, endemic in the Asian-Pacific region and, as recently discovered, in southern Chile. Scrub typhus is rarely reported in travelers, most probably due to the lack of clinical experience and diagnostic tests in non-endemic countries. We report the first case of imported scrub typhus in South America. CASE PRESENTATION: A 62-year-old tourist from South Korea presented severely ill with fever, rash, and eschar in Santiago, Chile. Laboratory exams showed thrombocytopenia and elevated inflammation parameters, hepatic enzymes, and LDH. With the clinical suspicion of scrub typhus, empirical treatment with doxycycline was initiated and the patient recovered rapidly and without complications. The diagnosis was confirmed by IgM serology and by real-time PCR, which demonstrated infection with Orientia tsutsugamushi (Kawasaki clade). CONCLUSIONS: Only due to the emerging clinical experience with endemic South American scrub typhus and the recent implementation of appropriate diagnostic techniques in Chile, were we able to firstly identify and adequately manage a severe case of imported scrub typhus in South America. Physicians attending febrile travelers need to be aware of this rickettsiosis, since it requires prompt treatment with doxycycline to avoid complications.

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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.

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Resumen El tifus de los matorrales, causado por Orientia tsutsugamushi y transmitido por larvas de ácaros trombicúlideos de roedores silvestres es una rickettsiosis endémica en el Asia Pacífico. Luego del primer caso identificado en Chile en el año 2006, nuestro grupo ha identificado más de 30 casos a partir del año 2015. Los casos se han presentado con un marcado predominio en meses de verano, y su presentación clínica incluye fiebre, exantema y una mancha negra en el sitio de inoculación. Otros hallazgos frecuentes han sido cefalea intensa, sudoración nocturna, aumento de PCR, VHS y transaminasas hepáticas. La gran mayoría de los pacientes se han diagnosticado en el sur de Chile (principalmente la isla de Chiloé), pero recientemente también se han presentado casos en la Región Metropolitana, en personas volviendo de viajes al sur de Chile. Los médicos clínicos deben estar informados de esta enfermedad emergente en el país, de modo de sospecharla e iniciar terapia empírica con doxiciclina. La confirmación de estos casos con los métodos diagnósticos disponibles en Chile contribuirá a una mejor comprensión del rango epidemiológico y la relevancia clínica de esta infección nueva en el país.

Scrub typhus, caused by Orientia tsutsugamushi and transmitted by larvae of trombiculid mites, is an endemic rickettsiosis in the Asia Pacific region. After the first identification of a case in Chile in 2006, more than 30 cases have been diagnosed by our group since 2015. Cases were detected predominantly during the Chilean summer months. Patients presented with fever, rash, and a typical eschar at the inoculation site; other frequent findings were intense headache, night sweats, increased laboratory markers of inflammation and transaminases. The vast majority of cases have been diagnosed in southern Chile (mainly Chiloé Island), although recently some cases were also identified in the central Metropolitan Region in patients returning from trips to southern Chile. Physicians attending Chilean patients should be aware of this emerging infection to be able to initiate empirical therapy with doxycycline. The confirmation of cases by the diagnostic methods available in Chile will contribute to a better understanding of the epidemiological and clinical relevance of this emerging infection in South America.

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Using a large, passive, febrile surveillance program in Iquitos, Peru, we retrospectively tested human blood specimens for scrub typhus group orientiae by ELISA, immunofluorescence assay, and PCR. Of 1,124 participants, 60 (5.3%) were seropositive, and 1 showed evidence of recent active infection. Our serologic data indicate that scrub typhus is present in the Peruvian Amazon.

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