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Hosts and vectors of scrub typhus in Chile: epidemiological study and molecular analyses of Orientia infection in rodents and rodent-associated mites
(Springer Science and Business Media LLC, 2024-12-18)
Constanza Martínez-Valdebenito
;
Gerardo Acosta-Jamett
;
Rayitray Abello
;
Ju Jiang
;
Allen L. Richards
<jats:title>Abstract</jats:title><jats:p><jats:italic>Candidatus</jats:italic> Orientia chiloensis causes scrub typhus over a wide geographical range in southern Chile. The life cycle, including vectors and reservoirs of this novel rickettsial pathogen, is incompletely understood. We analyzed rodent tissue and rodent-associated mite samples collected during a field study in six localities on Chiloé Island, where human scrub typhus cases have occurred. Using molecular methods, we detected <jats:italic>Orientia</jats:italic> DNA in 24.8% of rodents, belonging to five of seven captured species. <jats:italic>Orientia</jats:italic>-infection rates showed geographical variations, but were not influenced by rodent species, sex, age, and mite infestation. Phylogenetic analysis showed that <jats:italic>Orientia</jats:italic> sequences from trombiculid mites (<jats:italic>Proschoengastia eloisae</jats:italic>) were identical to those from scrub typhus patients from the same region. The results suggest that these rodent-associated mites serve as vectors and play an important role in the ecology of scrub typhus in southern Chile. Further studies are required to determine whether <jats:italic>Orientia</jats:italic>-infected rodents can also serve as reservoir of <jats:italic>Orientia</jats:italic> in Chile.</jats:p> <jats:p><jats:bold>Graphical Abstract</jats:bold></jats:p>
1Scopus© Citations 8
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Different Safety Pattern of an Inactivated SARS-CoV-2 Vaccine (CoronaVac®) According to Age Group in a Pediatric Population from 3 to 17 Years Old, in an Open-Label Study in Chile
(2023)
Nicole Le Corre
;
Katia Abarca
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Patricio Astudillo
;
Marcela Potin
;
Sofía López
<jats:p>During the COVID-19 pandemic, the importance of vaccinating children against SARS-CoV-2 was rapidly established. This study describes the safety of CoronaVac® in children and adolescents between 3- and 17-years-old in a multicenter study in Chile with two vaccine doses in a 4-week interval. For all participants, immediate adverse events (AEs), serious AEs (SAEs), and AEs of special interest (AESIs) were registered throughout the study. In the safety subgroup, AEs were recorded 28 days after each dose. COVID-19 surveillance was performed throughout the study. A total of 1139 individuals received the first and 1102 the second dose of CoronaVac®; 835 were in the safety subgroup. The first dose showed the highest number of AEs: up to 22.2% of participants reported any local and 17.1% systemic AE. AEs were more frequent in adolescents after the first dose, were transient, and mainly mild. Pain at the inoculation site was the most frequent AE for all ages. Fever was the most frequent systemic AE for 3–5 years old and headache in 6–17 years old. No SAEs or AESIs related to vaccination occurred. Most of the COVID-19 cases were mild and managed as outpatients. CoronaVac® was safe and well tolerated in children and adolescents, with different safety patterns according to age.</jats:p>
Scopus© Citations 3 3
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Scrub typhus in Tierra del Fuego: a tropical rickettsiosis in a subantarctic region
(2021)
WEITZEL, THOMAS
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AYLWIN RAMIREZ, MABEL CRISTINA
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Constanza Martínez-Valdebenito
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Gerardo Acosta-Jamett
;
Katia Abarca
10Scopus© Citations 10
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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species
(2020)
Gerardo Acosta-Jamett
;
Constanza Martínez-Valdebenito
;
Esperanza Beltrami
;
María Carolina Silva-de La Fuente
;
Ju Jiang
23 1Scopus© Citations 42
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Molecular Description of a Novel <i>Orientia</i> Species Causing Scrub Typhus in Chile
(2020)
Katia Abarca
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Constanza Martínez-Valdebenito
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Jenniffer Angulo
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Ju Jiang
;
Christina M. Farris
1Scopus© Citations 78 1
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Safety and Immunogenicity of an Inactivated Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine in a Subgroup of Healthy Adults in Chile
(2021)
Susan M Bueno
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Katia Abarca
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GONZALEZ, PABLO
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Nicolás M S Gálvez
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Jorge A Soto
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>The development of effective vaccines against coronavirus disease 2019 is a global priority. CoronaVac is an inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine with promising safety and immunogenicity profiles. This article reports safety and immunogenicity results obtained for healthy Chilean adults aged ≥18 years in a phase 3 clinical trial.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Volunteers randomly received 2 doses of CoronaVac or placebo, separated by 2 weeks. A total of 434 volunteers were enrolled, 397 aged 18–59 years and 37 aged ≥60 years. Solicited and unsolicited adverse reactions were registered from all volunteers. Blood samples were obtained from a subset of volunteers and analyzed for humoral and cellular measures of immunogenicity.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The primary adverse reaction in the 434 volunteers was pain at the injection site, with a higher incidence in the vaccine than in the placebo arm. Adverse reactions observed were mostly mild and local. No severe adverse events were reported. The humoral evaluation was performed on 81 volunteers. Seroconversion rates for specific anti-S1-receptor binding domain (RBD) immunoglobulin G (IgG) were 82.22% and 84.44% in the 18–59 year age group and 62.69% and 70.37% in the ≥60 year age group, 2 and 4 weeks after the second dose, respectively. A significant increase in circulating neutralizing antibodies was detected 2 and 4 weeks after the second dose. The cellular evaluation was performed on 47 volunteers. We detected a significant induction of T-cell responses characterized by the secretion of interferon-γ (IFN-γ) upon stimulation with Mega Pools of peptides from SARS-CoV-2.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Immunization with CoronaVac in a 0–14 schedule in Chilean adults aged ≥18 years is safe, induces anti-S1-RBD IgG with neutralizing capacity, activates T cells, and promotes the secretion of IFN-γ upon stimulation with SARS-CoV-2 antigens.</jats:p> </jats:sec>
Scopus© Citations 75 1
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Safety and Non-Inferiority Evaluation of Two Immunization Schedules with an Inactivated SARS-CoV-2 Vaccine in Adults: A Randomized Clinical Trial
(2022)
Katia Abarca
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Carolina Iturriaga
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Marcela Urzúa
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Nicole Le Corre
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Augusto Pineda
<jats:p>Several vaccines have been developed to control the COVID-19 pandemic. CoronaVac®, an inactivated SARS-CoV-2 vaccine, has demonstrated safety and immunogenicity, preventing severe COVID-19 cases. We investigate the safety and non-inferiority of two immunization schedules of CoronaVac® in a non-inferiority trial in healthy adults. A total of 2302 healthy adults were enrolled at 8 centers in Chile and randomly assigned to two vaccination schedules, receiving two doses with either 14 or 28 days between each. The primary safety and efficacy endpoints were solicited adverse events (AEs) within 7 days of each dose, and comparing the number of cases of SARS-CoV-2 infection 14 days after the second dose between the schedules, respectively. The most frequent local AE was pain at the injection site, which was less frequent in participants aged ≥60 years. Other local AEs were reported in less than 5% of participants. The most frequent systemic AEs were headache, fatigue, and myalgia. Most AEs were mild and transient. There were no significant differences for local and systemic AEs between schedules. A total of 58 COVID-19 cases were confirmed, and all but 2 of them were mild. No differences were observed in the proportion of COVID-19 cases between schedules. CoronaVac® is safe, especially in ≥60-year-old participants. Both schedules protected against COVID-19 hospitalization.</jats:p>
1 2Scopus© Citations 9
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Inactivated Vaccine-Induced SARS-CoV-2 Variant-Specific Immunity in Children
(2022)
Jorge A. Soto
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Felipe Melo-González
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Cristián Gutierrez-Vera
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Bárbara M. Schultz
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Roslye V. Berríos-Rojas
<jats:p>This work evaluated the immune response induced by two doses of CoronaVac separated by 4 weeks in healthy children and adolescents in Chile. To date, few studies have described the effects of CoronaVac in the pediatric population.</jats:p>
1Scopus© Citations 20 16
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Human seroepidemiology of Rickettsia and Orientia species in Chile – A cross-sectional study in five regions
(2020)
WEITZEL, THOMAS
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Gerardo Acosta-Jamett
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Ju Jiang
;
Constanza Martínez-Valdebenito
;
Christina M. Farris
11 1Scopus© Citations 11
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Scrub typhus risk in travelers to southern Chile
(2019)
Thomas Weitzel
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Gerardo Acosta-Jamett
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Constanza Martínez-Valdebenito
;
Allen L. Richards
;
Martin P. Grobusch
2Scopus© Citations 16

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