Browsing by Author "Abarca Villaseca, Katia "

Now showing 1 - 20 of 22
  • Thumbnail Image
    Item
    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
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Descripción clínica y epidemiológica de la infección por Clostridium difficile en población pediátrica
    (2015) Maccioni, Andrea; Cerda, Jaime; Terrazas, Claudia; Abarca Villaseca, Katia
  • No Thumbnail Available
    Item
    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.
  • Thumbnail Image
    Item
    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
  • Thumbnail Image
    Item
    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.
  • Thumbnail Image
    Item
    Flea and ticks species from dogs in urban and rural areas in four districts in Chile
    (2016) Abarca Villaseca, Katia; Garate, D.; Lopez, J.; Acosta, G.
  • Thumbnail Image
    Item
    Hospitalización por influenza en un Servicio de Pediatría de Santiago de Chile, 2001-2005
    (SOC CHILENA INFECTOLOGIA, 2008) Vega Briceño, Luis Enrique; Platzer M., Lisbeth; Oyarzún Andrade, María Angélica; Abarca Villaseca, Katia ; Pulgar B., Dahiana; Sánchez Díaz, Ignacio
  • Thumbnail Image
    Item
    Hosts and vectors of scrub typhus in Chile: epidemiological study and molecular analyses of Orientia infection in rodents and rodent-associated mites
    (2024) Martínez Valdebenito, Constanza; Acosta-Jamett, Gerardo; Abello, Rayitray; Jiang, Ju; Richards, Allen L.; Abarca Villaseca, Katia; Weitzel, Thomas
    Abstract Candidatus 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 Orientia DNA in 24.8% of rodents, belonging to five of seven captured species. Orientia-infection rates showed geographical variations, but were not influenced by rodent species, sex, age, and mite infestation. Phylogenetic analysis showed that Orientia sequences from trombiculid mites (Proschoengastia eloisae) 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 Orientia-infected rodents can also serve as reservoir of Orientia in Chile. Graphical Abstract
  • Thumbnail Image
    Item
    Imported scrub typhus: first case in South America and review of the literature
    (2018) Weitzel, Thomas; Martínez Valdebenito, Constanza Pamela; Abarca Villaseca, Katia; Aylwin, Mabel; Jiang, Ju; Munita, Jose M.; Thompson, Luis; Richards, Allen L.
    Abstract 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.Abstract 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.
  • Thumbnail Image
    Item
    Infecciones asociadas a la atención en salud (IAAS) en pacientes pediátricos post-operados de cardiopatías congénitas
    (2014) Barriga, J.; Cerda, Jaime; Abarca Villaseca, Katia; Ferrés Garrido, Marcela Viviana; Fajuri, P.; Riquelme, M.; Carrillo, D.; Clavería Rodríguez, Cristian
  • No Thumbnail Available
    Item
    Infection by Bartonella henselae in immunocompetent patients: Cat scratch disease
    (SOC MEDICA SANTIAGO, 1996) Abarca Villaseca, Katia; Vial, P. A.; Rivera, M.; Garcia, C.; Oddo, D.; Prado, P.; Ferres, M.
    Background: Cat scratch disease, whose etiologic agent is Bartonella benselae, is a benign disease in immunocompetent subjects, characterized by lymphadenopathy of prolonged course and occasional involvement of other organs such as liver, spleen, central nervous system, eye and lung. In immunocompromised patients, the infection is bacteremic and disseminated. Aims: To report Chilean cases of cat scratch disease. Patients and methods: Ten children (seven male, aged between 6 and 13 years old) with histologically or serologically confirmed cat scratch disease are reported. Results: Lymphadenopathy location was pre auricular in four cases, axillary in two, inguinal in two and epitrochlear in two. Three children had fever over 39 degrees C and two had a Parinaud syndrome. Nine children had a history of cat scratch and one of a cat byte. Six had an erythrocyte sedimentation rate over 40. Lymph node ultrasound examination was a useful diagnostic tool. Two patients had splenic granulomas. Lymph node biopsies were obtained in four cases, showing a suppurative granulomatous lymphadenitis in all and a positive Wartbin-Starry stain in two. Serology, done in patients without histological confirmation was positive with titles ranging from 1:64 to 1:8192. All patients had a satisfactory outcome with regression of lymphadenopathy. Conclusions: Infections by Bartonella hemselae occur in the Chilean population and must be considered in the differential diagnosis of regional lymph node enlargement.
  • Thumbnail Image
    Item
    Influenza: vacunación a nuevos grupos etarios.
    (2007) Abarca Villaseca, Katia
  • No Thumbnail Available
    Item
    Lyme Borreliosis in Chile. Report of a child probably infected by imported pets
    (1996) Ribera M., M.; Abarca Villaseca, Katia; Prado D., P.; Lobos M., T.; Palacios F., O.; Ferrés G., M.; Mesa, T.; Vial C., P.
    Lyme disease, caused by the spirochete Borrelia burgdorferi, has several clinical manifestations and is transmitted to man by tick bites. In Chile and Latin America, several cases have been reported, but none with immnoblot confirmation or isolation of the infecting organism. We report a 9 year old boy consulting with bilateral facial palsy, polyradiculoneuritis with tetraparesis and meningeal irritation. Cerebrospinal fluid analysis showed increased protein concentration without pleocytosis and negative viral or bacterial cultures. IgM antibodies against Borrelia burgdorferi, were positive by ELISA and were confirmed by immunoblot at the Reference Laboratory of the University of Connecticut. The child had a recent contact with hamsters brought from Germany. The substantiation of Lyme disease existence in Chile should prompt the search and isolation of the causal agent.
  • Thumbnail Image
    Item
    Molecular Description of a Novel Orientia Species Causing Scrub Typhus in Chile
    (2020) Abarca Villaseca, Katia; Martinez-Valdebenito, C.; Angulo, J.; Jiang, J.; Farris, C. M.; Richards, A. L.; Acosta-Jamett, G.; Weitzel, T.
  • Thumbnail Image
    Item
    One Health in Practice: A Pilot Project for Integrated Care of Zoonotic Infections in Immunocompromised Children and Their Pets in Chile
    (2016) Peña Donati, Anamaría; Abarca Villaseca, Katia; Weitzel, T.; Gallegos J.; Cerda, Jaime; García Cañete, Patricia; López, J.
  • Thumbnail Image
    Item
    Prevalence and Risk Factors for Echinococcal Infection in a Rural Area of Northern Chile : A Household-Based Cross-Sectional Study
    (2014) Acosta Jamett, Gerardo; Weitzel, Thomas; Boufana, Belgees; Adones, Claudia; Bahamonde, Andrea; Abarca Villaseca, Katia; Craig, Philip S.; Reiter-Owona, Ingrid
  • Thumbnail Image
    Item
    Safety and immunogenicity evaluation of recombinant BCG vaccine against respiratory syncytial virus in a randomized, double-blind, placebo-controlled phase I clinical trial
    (2020) Abarca Villaseca, Katia; Rey Jurado, Emma; Muñoz Durango, Natalia; Soto Ramírez, Jorge Andrés; Gálvez Arriagada, Nicolás Marcelo Salvador; Borzutzky Schachter, Arturo; Cerda, Jaime; Villarroel del Pino, Luis A.; González Muñoz, Pablo Alberto; González Aramundiz, José Vicente; Bueno Ramírez, Susan; Kalergis Parra, Alexis Mikes; Valdés-Ferrada, J.; Iturriaga, C.; Urzúa, M.; Madrid, V.; Bueno Ramírez, Susan; Vázquez, Y.
  • Thumbnail Image
    Item
    Seroprevalencia de Bartonella henselae en personas con riesgo ocupacional
    (2016) Abarca Villaseca, Katia; Troncoso, I.; Fischer, C.; Arteaga, F.; Espinoza, C.; Azócar, T.
  • Thumbnail Image
    Item
    Tenencia de mascotas en pacientes inmunocomprometidos: actualización y consideraciones veterinarias y médicas
    (2013) López, Javier; Peña Donati, Anamaría; Pérez Pérez, Regina Elizabeth; Abarca Villaseca, Katia