Browsing by Author "Abarca Villaseca, Katia"

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    A phase 2, randomized double-blind safety and pharmacokinetic assessment of respiratory syncytial virus (RSV) prophylaxis with motavizumab and palivizumab administered in the same season
    (2010) Fernández, P.; Trenholme, A.; Abarca Villaseca, Katia; Griffin, M. P.; Hultquist, M.; Harris, B.; Losonsky, G. A.
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    Aberrant T cell immunity triggered by human Respiratory Syncytial Virus and human Metapneumovirus infection
    (2017) González, A. E.; Lay, M. K.; Jara, E. L.; Espinoza, J. A.; Gómez, R. S.; Soto, J.; Rivera, C. A.; Abarca Villaseca, Katia; Bueno Ramírez, Susan; Riedel, C. A.; Kalergis Parra, Alexis Mikes
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    Absence of convincing evidence of Coxiella burnetii infection in Chile: a cross-sectional serosurvey among healthy adults in four different regions
    (2016) Weitzel, Thomas; López, Javier; Acosta-Jamett, Gerardo; Edouard, Sophie; Parola, Philippe; Abarca Villaseca, Katia
    Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.Abstract Background Coxiella burnetii is an important zoonotic pathogen of global distribution. Still, in most parts of South America including Chile, systematic epidemiological data are lacking. The presented study aims to determine the seroprevalence of Coxiella burnetii antibodies in healthy adults of four different regions in Chile. Methods A cross-sectional study was performed, which included healthy adults living in rural and urban areas of four cities located in different regions in northern, central, and southern Chile. In urban sectors, households were chosen by double stratified random sampling, while in rural areas convenience sampling was performed. Serum specimens were taken and screened for the presence of IgG antibodies against C. burnetii phase II antigen using a commercial ELISA kit. Positive and indeterminate results were confirmed by a reference laboratory using indirect immunofluorescence assay (IFA). Results A total of 1112 individuals were included. Of those, 8 were positive by ELISA, but only one sample was confirmed using IFA. Statistical analysis for population freedom from disease revealed a high probability that C. burnetii was absent in our study population. Conclusion Our work provides the first epidemiological data on human Q fever in Chile indicating either a very low endemicity or the absence of this pathogen in the studied areas.
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    An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection
    (2018) Díaz Acevedo, Fabián Esteban; Abarca Villaseca, Katia; Kalergis Parra, Alexis Mikes
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    Canine seroprevalence to Orientia species in southern Chile: A cross-sectional survey on the Chiloe A Island
    (2018) Weitzel, Thomas; Jiang, Ju; Acosta-Jamett, Gerardo; Martinez-Valdebenito, Constanza; Lopez, Javier; Richards, Allen L.; Abarca Villaseca, Katia
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    Clinical-epidemiological analysis of infections in pediatric patients with liver and heart trasplants
    (SOC CHILENA INFECTOLOGIA, 2024) Jung Montanares, Francisca Andrea; Astudillo Paredes, Patricio Andrés; Vrsalovic Papic, Katica Ivanka; Rosales Alfaro, Valentina José; Marinovic, Nicole L'Huillier; Vizcaya Altamirano, María Cecilia; Ferres Garrido, Marcela Viviana; Urcelay Montecinos, Gonzalo Eduardo; Gana Ansaldo, Juan Cristobál; Abarca Villaseca, Katia
    Background: Liver and heart transplantation represents the definitive treatment for end-stage failure of these organs. In recent years, an increasing number of pediatric patients have undergone these procedures, which are associated with various complications. Among them, infections stand out as one of the main causes of morbidity and mortality. Aim: To describe the infections that affect pediatric recipients of liver and heart transplants (Tx.). Methods: A characterization of the type and timing of infections identified in 31 children who underwent heart transplantation and 27 who underwent liver transplantation at a tertiary university hospital since 2002 (cardiac Tx) and 2009 (hepatic Tx), both to 2022 is presented. Results: Biliary atresia and dilated cardiomyopathy were the main reasons for liver and heart transplantation, respectively. Bacterial infections predominated during the first month after these surgical procedures, while viral infections predominated later. Bacterial infections in general, and bacteriemia were more common in liver Tx. recipients. Cytomegalovirus (CMV) and Epstein-Barr virus, mainly in the form of reactivations, were the most frequently identified viruses, with a higher frequency of CMV in liver Tx. recipients. One patient from each group died in a late period due to bacterial sepsis, without a specific agent identified. Conclusion: The preponderance of infections due to latent viral agents, such as CMV, in pediatric liver or heart transplant recipients, reveals the need to optimize the management of these infections in this growing population in Chile.
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    Concordancia del hisopado nasal con el hisopado nasofaríngeo en la detección de virus respiratorios por inmunofluorescencia directa
    (2014) Del Pozo Bascuñan, Paulina Andrea; Abarca Villaseca, Katia; Concha Murray, Ida; Cerda, Jaime
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    Descripción clínica y epidemiológica de la infección por Clostridium difficile en población pediátrica
    (2015) Maccioni, Andrea; Cerda, Jaime; Terrazas, Claudia; Abarca Villaseca, Katia
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    Detección del SARS-CoV-2 mediante RT-qPCR utilizando saliva en pacientes ambulatorios con estudio de COVID-19
    (2022) Perret Pérez, Cecilia; Abarca Villaseca, Katia; Solari Gajardo, Sandra; Aguilera, Pablo; García-Huidobro Munita, Diego Nicolas; Olivares, Felipe; Palma, Carlos; Contreras, Ana María; Martínez Valdebenito, Constanza Pamela; Ferrés, Marcela
    La pandemia de COVID-19 ha afectado a millones de personas en todo el mundo. La identificación de sujetos infectados ha sido importante para el control. Objetivo: Evaluar el rendimiento deuna reacción de polimerasa en cadena (RPC) cuantitativa en tiempo real (en inglés: RT-qPCR) para SARS-CoV-2, utilizando saliva como matriz en comparación con un hisopado nasofaríngeo (HNF). Metodología: Se reclutaron adultos en atención ambulatoria, la mayoría sintomáticos. Fueron estudiadas 530 muestras pareadas de saliva e HNF con RT-qPCR. Resultados: Fueron positivas 59 muestras de HNF y 54 de saliva. La sensibilidad con saliva fue 91%, especificidad 100%, el valor predictor positivo (VPP) 100%, valor predictor negativo (VPN) 98%. El índice Kappa fue de 0,95 y LR-0,08. En promedio, el umbral de ciclo (en inglés cycle threshold-CT) de la saliva fue 3,99 puntos más alto que los de HNF (p < 0,0001) mostrando que la carga viral (CV) es menor en saliva. La carga viral en ambas disminuyó con el tiempo después del inicio de los síntomas. El muestreo de saliva fue preferido por los sujetos en lugar de HNF. Conclusión: Este estudio demuestra que la RPC para SARS-CoV-2 utilizando saliva, es adecuada para el diagnóstico de COVID-19 en adultos ambulatorios,especialmente en la etapa temprana de los síntomas.
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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) Le Corre, Nicole; Abarca Villaseca, Katia; Astudillo, Patricio André; Potin Santander, Marcela Patricia; López, Sofía; Goldsack, Macarena; Valenzuela Guerrero, Vania; Schilling Redlich, Andrea; Gaete, Victoria; Rubio, Lilian; Calvo, Mario; Twele, Loreto; González, Marcela; Fuentes, Daniela; Gutiérrez Muñoz, Valentina José; Reyes Zaldivar, Felipe Tomás; Tapia, Lorena I.; Villena, Rodolfo; Retamal Díaz, Angello; Cárdenas, Antonio; Alarcón Bustamante, Eduardo; Xin, Qianqian; González Aramundiz, José Vicente; Álvarez Figueroa, María Javiera; González Muñoz, Pablo Alberto; Bueno Ramírez, Susan; Soto Ramírez, Jorge Andrés; Perret Pérez, Cecilia; Meng, Xing; Kalergis Parra, Alexis Mikes
    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.
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    Differential immune response induced by two immunization schedules with an inactivated SARS-CoV-2 vaccine in a randomized phase 3 clinical trial
    (2022) Galvez Arriagada, Nicolás Marcelo Salvador; Pacheco Ruidiaz, Gaspar Andrés; Schültz Lombardic, Barbara Melinka; Melo González, Felipe Andrés; Soto Ramírez, Jorge Andrés; Duarte Peñaloza, Luisa Fernanda; González Carreño, Liliana Andrea; Rivera Pérez, Daniela Belén; Ríos Raggio, Mariana; Berríos, Roslye V.; Vazquéz Hernandéz, Yaneisi; Moreno Tapia, Daniela Paz; Vallejos Galvez, Omar Patricio; Andrade Parra, Catalina Andrea; Hoppe Elsholz, Guillermo; Iturriaga, Carolina; Urzua, Marcela; Navarrete, María S.; Rojas González, Álvaro Miguel; Fasce Pineda, Rodrigo Andrés; Fernández, Jorge; Mora, Judith; Ramírez, Eugenio; Gaete Argel, Aracelly; Acevedo Blanco, Mónica Andrea; Valiente Echeverría, Fernando; Soto Rifo, Ricardo; Weiskopf, Daniela; Grifoni, Alba; Sette, Alessandro; Zeng, Gang; Meng, Weining; González Aramundiz, José Vicente; Goldblatt, David; Acuna González, Pablo Ernesto; Abarca Villaseca, Katia; Bueno Ramírez, Susan Marcela; Kalergis Parra, Alexis Mikes
    Background: The development of vaccines to control the COVID-19 pandemic progression is a worldwide priority. CoronaVac® is an inactivated SARS-CoV-2 vaccine approved for emergency use with robust efficacy and immunogenicity data reported in trials in China, Brazil, Indonesia, Turkey, and Chile. Methods: This study is a randomized, multicenter, and controlled phase 3 trial in healthy Chilean adults aged ≥18 years. Volunteers received two doses of CoronaVac® separated by two (0-14 schedule) or four weeks (0-28 schedule). 2,302 volunteers were enrolled, 440 were part of the immunogenicity arm, and blood samples were obtained at different times. Samples from a single center are reported. Humoral immune responses were evaluated by measuring the neutralizing capacities of circulating antibodies. Cellular immune responses were assessed by ELISPOT and flow cytometry. Correlation matrixes were performed to evaluate correlations in the data measured. Results: Both schedules exhibited robust neutralizing capacities with the response induced by the 0-28 schedule being better. No differences were found in the concentration of antibodies against the virus and different variants of concern between schedules. Stimulation of PBMCs with MPs induced the secretion of IFN-γ and the expression of activation induced markers for both schedules. Correlation matrixes showed strong correlations between neutralizing antibodies and IFN-γ secretion. Conclusions: Immunization with CoronaVac® in Chilean adults promotes robust cellular and humoral immune responses. The 0-28 schedule induced a stronger humoral immune response than the 0-14 schedule.
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    Disruption of an antimycobacterial circuit between dendritic and helper T cells in human SPPL2a deficiency
    (2018) Kong, Xiao-Fei; Martínez Barricarte, Rubén; Kennedy, James; Mele, Federico; Lazarov, Tomi; Deenick, Elissa K.; Ma, Cindy S.; Breton, Gaëlle; Lucero, Kimberly B.; Abarca Villaseca, Katia
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    Endemic Scrub Typhus in South America
    (2016) Weitzel, T.; Dittrich, S.; López, J.; Phuklia, W.; Martínez, Constanza; Velásquez, K.; Blacksell, S.; Paris, D.; Abarca Villaseca, Katia
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    Endemic Scrub Typhus-like Illness, Chile
    (Centers for Disease Control an Prevention, 2011) Balcells Marty, María Elvira; Rabagliati Borie, Ricardo Miguel; García Cañete, Patricia Del Carmen; Poggi Mayorga, Helena Loreto; Oddo Benavides, Carlos David; Concha Rogazy, Marcela Andrea; Abarca Villaseca, Katia; Jiang, Ju; Kelly, Daryl J.; Richards, Allen L.; Fuerst, Paul A.
    We report a case of scrub typhus in a 54-year-old man who was bitten by several terrestrial leeches during a trip to Chiloe Island in southern Chile in 2006. A molecular sample, identified as related to Orientia tsutsugamushi based on the sequence of the 16S rRNA gene, was obtained from a biopsy specimen of the eschar on the patient's leg. Serologic analysis showed immunoglobulin G conversion against O. tsutsugamushi whole cell antigen. This case and its associated molecular analyses suggest that an Orientia-like agent is present in the Western Hemisphere that can produce scrub typhus-like illness. The molecular analysis suggests that the infectious agent is closely related, although not identical, to members of the Orientia sp. from Asia.
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    Evaluation of a new syringe presentation of reduced-antigen content diphtheria, tetanus, and acellular pertussis vaccine in healthy adolescents - A single blind randomized trial
    (2015) Pavia Ruz, Noris; Abarca Villaseca, Katia; Lepetic, Alejandro; Cervantes Apolinar, María Yolanda; Hardt, Karin; Jayadeva, Girish; Kuriyakose, Sherine; Han, Htay Htay; De La O, Manuel
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    Evidencia seroepidemiológica de exposición humana a Anaplasma sp en Santiago, Chile
    (2008) Abarca Villaseca, Katia; López del P., Javier; González A.,Patricia; Dabanch P., Jeannette; Torres Hidalgo, Marisa; Solari G., Verónica; Perret Pérez, Cecilia
    Objetivos y Método: Con el propósito de buscar mayor evidencia de exposición humana a Anaplasma sp en Chile, se estudiaron 108 personas en contacto con perros con ehrlichiosis canina (EC) (grupo de riesgo) y 61 personas sin antecedente de contacto con garrapatas ni con perros con EC (grupo control). Se aplicó encuesta sobre factores de riesgo e historia de cuadros sugerentes de ehrlichiosis/anaplasmosis al grupo de riesgo. En ambos grupos se determinó presencia de IgG anti-Anaplasma sp. Resultados: Se encontró significativa mayor prevalencia de anticuerpos anti-Anaplasma sp en el grupo de riesgo que en el grupo control (18,5 versus 3,3%), p < 0,005. No se encontraron factores de riesgo asociados a sero-positividad, ni personas con historia sugerente de ehrlichiosis/anaplasmosis clínica. Noventa y cuatro por ciento de las viviendas del grupo de riesgo presentaba infestación por garrapatas. Discusión: Se evidencia mayor riesgo de exposición humana a Anaplasma sp en personas en contacto cercano con perros con EC y que habitan viviendas con infestación por garrapatas.
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    Exactitud y utilidad diagnóstica de la IgM en infecciones por Bartonella henselae
    (2013) Abarca Villaseca, Katia; Winter, Matías; Marsac, Delphine; Palma, Carlos; Contreras, Ana M.; Ferrés Garrido, Marcela Viviana
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    Exome Sequencing Reveals Primary Immunodeficiencies in Children with Community-Acquired Pseudomonas aeruginosa Sepsis
    (2016) Asgari, S.; Mclaren, P. J.; Peake, J.; Wong, M.; Wong, R.; Bartha, I.; Francis, J. R.; Abarca Villaseca, Katia; Gelderman, K. A.; Agyeman, P.; Aebi, C.; Berger Silva, Christian; Fellay, J.; Schlapbach, L. J.
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