Endemic Scrub Typhus in South America

Weitzel, Thomas; Dittrich, Sabine; López, Javier; Phuklia, Weerawat; Martínez-Valdebenito, Constanza; Velásquez, Katia; Blacksell, Stuart D.; Paris, Daniel; Abarca, Katia

doi:10.1056/nejmoa1603657

Cited by 211 publications

(184 citation statements)

References 22 publications

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“…The disease is known to occur throughout the Asia-Pacific region but its range may be larger, with possible case reports in Africa [3] and South America [4, 5]. In Southeast Asia, it is thought that up to 1 million cases occur per year [6], and a significant proportion of hospital admissions for acute undifferentiated fever (AUF) are attributable to scrub typhus [4, 6–8].…”

Section: Introductionmentioning

confidence: 99%

Use of eschar swabbing for the molecular diagnosis and genotyping of Orientia tsutsugamushi causing scrub typhus in Quang Nam province, Vietnam

et al. 2017

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BackgroundScrub typhus is a rickettsiosis which is caused by Orientia tsutsugamushi and occurs throughout the Asia-Pacific region. Molecular diagnosis of rickettsioses using eschar swabs has recently emerged, and may be very useful for the diagnosis of these diseases in tropical settings.Methodology/Principal findingsQuantitative polymerase chain reaction (qPCR) was used to detect O. tsutsugamushi DNA in whole blood and eschar swab specimens of 67 patients who were clinically suspected of scrub typhus in Quang Nam province, Vietnam. Among the 20 patients for whom both eschar and whole blood were obtained, 17 (85%) of the eschar specimens and 5 (25%) of the whole blood specimens tested positive for O. tsutsugamushi. Genetic analysis of the 56-kDa TSA gene sequences demonstrated that the 14 sequences obtained in this study, including 12 eschar swabs and 2 whole blood specimens, were related to 4 groups: Karp, Kawasaki, Gilliam (JG-v and TG-v) and TA716. The majority (9/14; 64.4%) of contemporary O. tsutsugamushi genotypes in Quang Nam province were related to the Karp group.ConclusionsThese results suggest that polyclonal antigen pools used for serological testing in the future should contain at least Karp, Kawasaki, Gilliam and TA716 antigens for Vietnamese patients, as well as patients who have traveled to Vietnam. qPCR after eschar swabbing should be considered for molecular diagnosis of scrub typhus in endemic patients as well as in travelers, since it is easy to perform and appears very useful for the rapid detection of Orientia tsutsugamushi in the early phase of infection.

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Section: Introductionmentioning

confidence: 99%

Use of eschar swabbing for the molecular diagnosis and genotyping of Orientia tsutsugamushi causing scrub typhus in Quang Nam province, Vietnam

et al. 2017

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“…The first description of a febrile disease thought to be scrub typhus, along with the morphology of the vector mites, appeared in Chinese literature in 313 A.D. [3]. Therefore, it seems to an ancient infectious disease that has long been confined to its endemic area, although several cases of suspected scrub typhus have been reported outside of the endemic region [4–7]. …”

Section: Introductionmentioning

confidence: 99%

Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas

Kim

Min

et al. 2017

PLoS Negl Trop Dis

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BackgroundScrub typhus is a mite-borne febrile disease caused by O. tsutsugamushi infection. Recently, emergence of scrub typhus has attracted considerable attention in several endemic countries in Asia and the western Pacific. In addition, the antigenic diversity of the intracellular pathogen has been a serious obstacle for developing effective diagnostics and vaccine.Methodology/Principal findingsTo understand the evolutionary pathway of genotypic diversification of O. tsutsugamushi and the environmental factors associated with the epidemiological features of scrub typhus, we analyzed sequence data, including spatiotemporal information, of the tsa56 gene encoding a major outer membrane protein responsible for antigenic variation. A total of 324 tsa56 sequences covering more than 85% of its open reading frame were analyzed and classified into 17 genotypes based on phylogenetic relationship. Extensive sequence analysis of tsa56 genes using diverse informatics tools revealed multiple intragenic recombination events, as well as a substantially higher mutation rate than other house-keeping genes. This suggests that genetic diversification occurred via frequent point mutations and subsequent genetic recombination. Interestingly, more diverse bacterial genotypes and dominant vector species prevail in Taiwan compared to other endemic regions. Furthermore, the co-presence of identical and sub-identical clones of tsa56 gene in geographically distant areas implies potential spread of O. tsutsugamushi genotypes.Conclusions/SignificanceFluctuation and diversification of vector species harboring O. tsutsugamushi in local endemic areas may facilitate genetic recombination among diverse genotypes. Therefore, careful monitoring of dominant vector species, as well as the prevalence of O. tsutsugamushi genotypes may be advisable to enable proper anticipation of epidemiological changes of scrub typhus.

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“…According to the national surveillance data of notifiable diseases in Japan, during 2004–2015, the number of reported ST cases was nearly constant; each year on average, 396 ST cases and 2 deaths (case-fatality rate 0.5%) were reported ( 3 ). ST was originally believed to be confined to the Asia–Pacific region; however, ST has recently been reported in Kenya ( 4 ) and southern Chile ( 5 ). In 1984, JSF was identified in western Japan ( 6 ).…”

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

Sando¹,

Suzuki²,

Katoh³

et al. 2018

Emerg. Infect. Dis.

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Japanese spotted fever (JSF) and scrub typhus (ST) are endemic to Japan and share similar clinical features. To document the clinical and epidemiologic characteristics that distinguish these 2 rickettsial diseases, during 2004–2015 we recruited 31 JSF patients, 188 ST patients, and 97 nonrickettsial disease patients from the southern Boso Peninsula of Japan. JSF occurred during April–October and ST during November–December. Patients with JSF and ST were significantly older and more likely to reside in wooded areas than were patients with nonrickettsial diseases. Spatial analyses revealed that JSF and ST clusters rarely overlapped. Clinical findings more frequently observed in JSF than in ST patients were purpura, palmar/plantar rash, hyponatremia, organ damage, and delayed defervescence after treatment. Although their clinical features are similar, JSF and ST differ in seasonality, geographic distribution, physical signs, and severity. Because a considerable percentage of patients did not notice rash and eschar, many rickettsial diseases might be underdiagnosed in Japan.

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Endemic Scrub Typhus in South America

Cited by 211 publications

References 22 publications

Use of eschar swabbing for the molecular diagnosis and genotyping of Orientia tsutsugamushi causing scrub typhus in Quang Nam province, Vietnam

Use of eschar swabbing for the molecular diagnosis and genotyping of Orientia tsutsugamushi causing scrub typhus in Quang Nam province, Vietnam

Diversification of Orientia tsutsugamushi genotypes by intragenic recombination and their potential expansion in endemic areas

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

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