Novel vector of scrub typhus in subantarctic Chile – evidence from human exposure

2021 ◽  
Author(s):  
Thomas Weitzel ◽  
María Carolina Silva-de la Fuente ◽  
Constanza Martínez-Valdebenito ◽  
Alexandr A Stekolnikov ◽  
Caricia Pérez ◽  
...  
Keyword(s):  
South America ◽  
Human Exposure ◽  
Research Team ◽  
Scrub Typhus ◽  
Southern Chile ◽  
Rickettsial Infection

Abstract 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.

scholarly journals First identification of trombiculid mites (Acari: Trombiculidae) on rodents captured on Chiloé Island, an endemic region of scrub typhus in southern Chile

2019 ◽  
Author(s):  
Gerardo Acosta-Jamett ◽  
Esperanza Beltrami ◽  
María Carolina Silva de La Fuente ◽  
Constanza Martinez-Valdebenito ◽  
Thomas Weitzel ◽  
...  
Keyword(s):  
South America ◽  
Host Specificity ◽  
Rural Areas ◽  
Hot Spots ◽  
Scrub Typhus ◽  
Rodent Species ◽  
Asia Pacific ◽  
Southern Chile ◽  
Site Specific ◽  
Trombiculid Mites

AbstractBackgroundScrub typhus in an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a certain region of the Asia-Pacific, called tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. The disease has recently been discovered on Chiloé Island in southern Chile. Still, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The aim of the present work was to study the prevalence of chiggers on different rodent species captured in sites identified as probably hot spots of scrub typhus on Chiloé Island in southern Chile.Methodology/Principal FindingsDuring austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. All study sites were rural areas on Chiloé Island, previously identified as localities of probable human infection with scrub typhus. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. We identified trombiculids of three genera. Colicus was the most abundant chigger (93%), prevalent in five of six sites, followed by Quadraseta (7%) and Paratrombicula (7%), which were in only one site. Infestation rates showed site specific differences, which were statistically different using a GLM model with binomial errors.Conclusions/SignificanceThis study firstly reports the presence of different rodent-associated chigger mites in a region with endemic scrub typhus in southern Chile. Colicus and two other genera of mites were found with high infestation rates in sites previously identified as hot spots of scrub typhus, suggesting their role as vectors and reservoirs of this emerging zoonosis in South America.Author SummaryScrub typhus is a chigger-transmitted zoonotic infection, which is endemic in the tsutsugamushi triangle in Asia-Pacific. Recently, a first focus of scrub typhus in South America has been confirmed on Chiloé Island in southern Chile. Still, the vectors of scrub typhus in this region remain unknown. We undertook a survey to study the prevalence of chiggers on different rodent species in areas identified as probable hot spots of scrub typhus on Chiloé Island. The study showed that 55% of rodents were infested by trombiculids. Three chigger genera were identified, of which Colicus was the most abundant. Chiggers showed low host specificity, but spatial differences. This first demonstration of rodent-associated chigger mites in hot spots of scrub typhus suggests their possible role as vectors of this infection in Chile.

Isolated Triggered Tremor Spots in South America and Implications for Global Tremor Activity

2019 ◽  
Author(s):  
Kevin Chao ◽  
Zhigang Peng ◽  
William B. Frank ◽  
Germán A. Prieto ◽  
Kazushige Obara
Keyword(s):  
South America ◽  
Seismic Station ◽  
Plate Boundary ◽  
Active Regions ◽  
Fault System ◽  
Southern Chile ◽  
Tectonic Tremor ◽  
Single Station ◽  
Chile Triple Junction ◽  
Triggered Tremor

ABSTRACT We report new observations of triggered tectonic tremor in three regions in South America along the plate boundary between the Nazca and South America plates: southern Chile, Ecuador, and central Colombia. In these regions, tremor was observed during the passage of large‐amplitude surface waves of recent large earthquakes, which occurred in South America and around the world. In southern Chile, triggered tremor was observed around an ambient tremor active zone in the Chile triple junction region. In Ecuador and central Colombia, only one seismic station in each region recorded triggered tremor. With a single‐station approach, we are able to estimate potential tremor sources in these regions. Triggered tremor in Ecuador is likely associated with an inland fault near the volcanic region. In central Colombia, triggered tremor may be associated with the Romeral fault system rather than the subduction zone interface. In addition, we summarize global observations of tremor‐triggering stress and background ambient tremor activity in 24 tremor‐active regions. Based on the global summary of triggered and ambient tremor activity, the relative lack of triggered tremor in central and northern Chile and Peru is consistent with the lack of background tremor activity in these regions, suggesting tectonic tremor occurs only in isolated regions along major faults.

Seismic imaging evidence that forearc underplating built the accretionary rock record of coastal North and South America

2019 ◽  
Vol 158 (1) ◽  
pp. 104-117 ◽  
Author(s):  
David W. Scholl
Keyword(s):  
South America ◽  
Subduction Zones ◽  
Seismic Imaging ◽  
Southern Chile ◽  
Late Palaeozoic ◽  
Aleutian Arc ◽  
Seaward Edge ◽  
Metamorphic Facies ◽  
North And South America ◽  
North And South

AbstractThe submerged forearcs of Pacific subduction zones of North and South America are underlain by a coastally exposed basement of late Palaeozoic to early Tertiary age. Basement is either an igneous massif of an accreted intra-oceanic arc or oceanic plateau (e.g. Cascadia(?), Colombia), an in situ formed arc massif (e.g. Aleutian Arc) or an exhumed accretionary complex of low and high P/T metamorphic facies of late Palaeozoic (e.g. southern Chile, Patagonia) and Mesozoic age (e.g. Alaska). Seismic studies at Pacific forearcs image frontal prisms of trench sediment accreted to the seaward edge of forearc basement. Frontal prisms tend to be narrow (10–40 km), weakly consolidated and volumetrically small (∼35–40 km3/km of trench). In contrast, deep seismic imaging of submerged forearcs commonly reveals large volumes (∼2000 km3/km of trench) of underplated material accreted at subsurface depths of ∼10–30 km to the base of forearc basement. Underplates have been imaged below the southern Chile, Ecuador–Colombia, north Cascade, Alaska, and possibly the eastern Aleutian forearcs. Deep underplates have also been observed below the Japan and New Zealand forearcs. Seismic imaging of northern and eastern Pacific forearcs supports the conclusion drawn from field and laboratory studies that exposed low and high P/T accretionary complexes accumulated in the subsurface at depths of 10–30 km. It seems significant that imaged underplated bodies are characteristic of modern well-sedimented subduction zones. It also seems likely that large Pacific-rim underplates store a significant fraction of sediment subducted in Cenozoic time.

Human exposure to mercury in San Jorge river basin, Colombia (South America)

2002 ◽  
Vol 289 (1-3) ◽  
pp. 41-47 ◽  
Author(s):  
Jesus Olivero ◽  
Boris Johnson ◽  
Eduardo Arguello
Keyword(s):  
South America ◽  
River Basin ◽  
Human Exposure

The genus Acellomyia González, a new taxonomic arrangement of its species and descriptions of a new genus and two new species from southern South America (Diptera: Tabanidae: Diachlorini)

Zootaxa ◽  
2017 ◽  
Vol 4337 (4) ◽  
pp. 523
Author(s):  
CHRISTIAN R. GONZÁLEZ
Keyword(s):  
Species Richness ◽  
New Species ◽  
South America ◽  
New Genus ◽  
Morphological Diversity ◽  
Southern Chile ◽  
Key To Species ◽  
Southern South America ◽  
Two New Species ◽  
Morphological Differences

The tabanid tribe Diachlorini (Diptera) is the most genus-rich tribe in the Tabanidae; the tribe is cosmopolitan, but the greatest species richness and morphological diversity are found in the Australasian and Neotropical Regions. A new arrangement for the species of Acellomyia González is given; Acellomyia lauta (Hine) is transferred to a new genus, Montismyia gen.n., based on its morphological differences from Acellomyia and geographical distribution. The morphological differences between Acellomyia and Montismyia gen. n. are discussed. Two new species, Acellomyia casablanca sp.n. and Acellomyia puyehue sp.n., are described from specimens collected in southern Chile. Comparison of the morphology of Acellomyia paulseni mapuche (Coscarón & Philip) stat.nov. indicate that they should be elevated to species rank. A key to species of Acellomyia is provided and diagnostic characters are illustrated. 

scholarly journals A RICKETTSIAL INFECTION IN CANADIAN VOLES

1946 ◽  
Vol 84 (1) ◽  
pp. 37-50 ◽  
Author(s):  
James A. Baker
Keyword(s):  
Guinea Pigs ◽  
Scrub Typhus ◽  
Living Cells ◽  
Rickettsial Infection ◽  
Contact Points ◽  
Inapparent Infection ◽  
On This Island ◽  
The Relationship ◽  
Lethal Doses ◽  
Infective Agent

From apparently normal voles captured on Grosse Isle, Province of Quebec, Canada, an infective agent has been grown in embryonated eggs, and by inoculation an inapparent infection was established in voles, mice, guinea pigs, hamsters, and rats. No growth of the agent was obtained in the absence of living cells, and the manner of its development in the yolk sac of embryonated eggs, as well as morphological, epidemiological, and pathogenic features, indicates a rickettsial nature. The inability to transmit infection by either cage or intrauterine contact points to a vector, and mites are shown to have a probable part in the epidemiology. Mice infected with the vole agent resist lethal doses of the Karp strain of scrub typhus, and certain epidemiological, morphological, and immunological features support the relationship indicated by the mouse tests. It is therefore concluded that voles on this island have an inapparent infection due to a rickettsia that may be related to the rickettsia of scrub typhus.

Scrub typhus risk in travelers to southern Chile

2019 ◽  
Vol 29 ◽  
pp. 78-79 ◽  
Author(s):  
Thomas Weitzel ◽  
Gerardo Acosta-Jamett ◽  
Constanza Martínez-Valdebenito ◽  
Allen L. Richards ◽  
Martin P. Grobusch ◽  
...  
Keyword(s):  
Scrub Typhus ◽  
Southern Chile

CLINICO-DEMOGRAPHIC PROFILE OF SCRUB TYPHUS IN UTTARAKHAND

2021 ◽  
pp. 34-36
Author(s):  
Fauzia Khan ◽  
Vandana Sardana
Keyword(s):  
Distress Syndrome ◽  
Scrub Typhus ◽  
Tertiary Care Hospital ◽  
Tertiary Care ◽  
Care Hospital ◽  
Serological Testing ◽  
Rickettsial Infection ◽  
Igm Antibodies ◽  
Gastrointestinal Intolerance ◽  
Complications And Mortality

BACKGROUND: Scrub typhus(ST) a rickettsial infection caused by Orientia tsutsugamushi and transmitted by trombiculid mites“chiggers” particularly Leptotrombidium deliense. It is one of the differential diagnoses of haemorrhagic fevers, especially if associated with acute respiratory distress syndrome and/or jaundice. A necrotic eschar at the inoculating site of the mite is pathognomic of ST.The western Himalayan regions of India, has been witnessing increased incidence of acute febrile illnesses over the years. AIM & OBJECTIVES : 1) To determine the frequency of ST in a tertiary health care hospital in Uttarakhand. 2) To understand the clinical spectrum and associated complications. 3) To analyze the demographic prole of ST cases. MATERIAL & METHODS: The retrospective study was carried out, over a period of 24 months (August 2015 to July 2017), which included cases of AFI, clinically suspected of ST. Serological testing was carried out by using commercial ELISA for specic IgM antibodies against O.tsutsugamushi. RESULTS: Out of the total 3854 cases of AFI attending the tertiary care hospital, the microbiology laboratory received a total of 760 clinically suspected cases of ST for serological testing, 494 cases (12.81%) were found positive for IgM antibodies against O.tsutsugamushi.The common symptoms noted were fever with headache, myalgias, gastrointestinal intolerance, followed by breathlessness, rash and jaundice. Eschar was seen only in 69 patients. The most common complication noticed was ARDS (8.29%) followed by hepatitis (6.88%), petechial heamorrhagic spots (38.3%) and sepsis (6.07%). Mortality rate was found to be 1.8%. The cases were mainly seen in the months between August to October which correlates the infection with the rainy season. CONCLUSION: ST should be considered as one of the differential diagnosis of AFI. Timely diagnosis and management becomes crucial to decrease/limit the diease burden, thus thwarting the onset of complications and mortality

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