Browsing by Author "Aguilera, Ximena"
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- ItemBaseline assessment of prevalence and geographical distribution of HPV types in Chile using self-collected vaginal samples(2008) Ferreccio Readi, Catterina; Corvalán R., Alejandro; Margozzini Maira, Paula; Viviani García, Paola; González, Claudia; Aguilera, Ximena; Gravitt, Patti EAbstract Background Chile has broad variations in weather, economics and population from the far desert north (Region 1) to the cold, icy south (Region 12). A home-based self-collected vaginal sampling was nested in the 2003 Chilean population-based health survey in order to explore the possibility of a type-specific geographical variation for human papillomavirus Methods The population was a national probability sample of people 17 years of age and over. Consenting women provided self-collected cervicovaginal swabs in universal collection media (UCM). DNA was extracted and typed to 37 HPV genotypes using PGMY consensus PCR and line blot assay. Weighted prevalence rates and adjusted OR were calculated. Results Of the 1,883 women participating in the health survey, 1,219 (64.7%) provided a cervicovaginal sample and in 1,110 (56.2% of participants and 66.5% of those eligible) the samples were adequate for analysis. Refusal rate was 16.9%. HPV prevalence was 29.2% (15.1% high-risk HPV and 14.1% low-risk HPV). Predominant high-risk types were HPV 16, 52, 51, 56 and 58. Predominant low-risk HPVs were HPV 84, CP6108, 62, 53 and 61. High-risk and low-risk HPV rates were inversely correlated between the regions. High-risk HPV prevalence was highest among the youngest women, whereas low-risk HPV increased slightly with age. Conclusion Self-obtained vaginal sampling is adequate for monitoring HPV in the community, for identifying high-risk areas, and for surveying the long term impact of interventions.
- ItemCase-Control Study of Risk Factors for Meningococcal Disease in Chile(2017) Olea, Andrea; Matute, Isabel; González, Claudia; Delgado, Iris; Poffald, Lucy; Pedroni, Elena; Alfaro, Tania; Hirmas, Macarena; Nájera, Manuel; Ferreccio Readi, Catterina; Gormaz, Ana; López, Darío; Loayza, Sergio; Gallegos, Doris; Fuentes, Rodrigo; Vial, Pablo; Aguilera, Ximena
- ItemGastric cancer is related to early Helicobacter pylori infection in a high-prevalence country(AMER ASSOC CANCER RESEARCH, 2007) Ferreccio, Catterina; Rollan, Antonio; Harris, Paul R.; Serrano, Carolina; Gederlini, Alessandra; Margozzini, Paula; Gonzalez, Claudia; Aguilera, Ximena; Venegas, Alejandro; Jara, AlejandroBackground and Aims: Chile ranks fifth in the world among countries with the highest incidence of gastric cancer. The aim was to quantify the association between Helicobacter pylori infection and gastric cancer mortality at the county of residence.
- ItemOvercoming Health Inequities: Spatial Analysis of Seroprevalence and Vaccination Against COVID-19 in Chile(2024) Ramirez-Santana, Muriel; Correa, Juan; Franz, Loreto Nunez; Apablaza, Mauricio; Rubilar, Paola; Vial, Cecilia; Cortes, Lina Jimena; Hormazabal, Juan; Canales, Luis; Vial, Pablo; Aguilera, XimenaBackground: In unequal economies, the spread of the first waves of the COVID-19 was usually associated with low socioeconomic status of individuals and their families. Chile exemplified this. By mid-2020, Chile had one of the highest SARS-CoV-2 infection rates in the world predominantly in poorer areas. A year later, the country launched a universal vaccination campaign based on the national strategy of immunization established in 1975. By 2022, Chile presented one of the highest COVID-19 vaccination coverages globally, reaching 94.3% of the population with the primary scheme by the end of 2022.Objective: This study analyzes the spatial distribution of SARS-CoV-2 seroprevalence at the beginning of the pandemic (2020) compared with the seroprevalence after 2 years of ongoing epidemic and COVID-19 vaccination campaigns (2022).Methods: Two population-based random samples of individuals aged 7 years and older from two Chilean cities were studied. Utilizing an enzyme-linked immunosorbent assay test, IgG antibodies were measured in serum of 1061 participants in 2020, and 853 in 2022.Results: Using the Global Moran's Index, the seroprevalence distribution pattern for the year 2020 showed clustering in the two cities. Conversely, seroprevalence and vaccinations were homogeneously distributed in 2022. These results show the success of the vaccination campaign in Chile, not only in coverage but also because it widely reached all individuals.Conclusions: The uptake of this preventive measure is high, regardless of the social and economic factors, achieving broad population immunity. The extensive deployment of the primary health care network contributed to reducing health inequities and promoting to universal health access.
- ItemSARS-CoV-2 infectivity and antigenic evasion: spotlight on isolated Omicron sub-lineages(2024) Barrera, Aldo; Martinez-Valdebenito, Constanza; Angulo, Jenniffer; Palma, Carlos; Hormazabal, Juan; Vial, Cecilia; Aguilera, Ximena; Castillo-Torres, Pablo; Pardo-Roa, Catalina; Balcells, Maria Elvira; Nervi, Bruno; Le Corre, Nicole; Ferres, MarcelaSince the SARS-CoV-2 outbreak in 2019, a diversity of viral genomic variants has emerged and spread globally due to increased transmissibility, pathogenicity, and immune evasion. By the first trimester of 2023 in Chile, as in most countries, BQ and XBB were the predominant circulating sub-lineages of Omicron. The molecular and antigenic characteristics of these variants have been mainly determined using non-authentic spike pseudoviruses, which is often described as a limitation. Additionally, few comparative studies using isolates from recent Omicron sub-lineages have been conducted. In this study, we isolated SARS-CoV-2 variants from clinical samples, including the ancestral B.1.1, Delta, Omicron BA.1, and sub-lineages of BA.2 and BA.5. We assessed their infectivity through cell culture infections and their antibody evasion using neutralization assays. We observed variations in viral plaque size, cell morphology, and cytotoxicity upon infection in Vero E6-TMPRSS2 cells for each variant compared to the ancestral B.1.1 virus. BA.2-derived sub-variants, such as XBB.1.5, showed attenuated viral replication, while BA.5-derived variants, such as BQ.1.1, exhibited replication rates similar to the ancestral SARS-CoV-2 virus. Similar trends were observed in intestinal Caco-2 cells, except for Delta. Antibody neutralization experiments using sera from individuals infected during the first COVID-19 wave (FWI) showed a consistent but moderate reduction in neutralization against Omicron sub-lineages. Interestingly, despite being less prevalent, BQ.1.1 showed a 6.1-fold greater escape from neutralization than XBB.1.5. Neutralization patterns were similar when tested against sera from individuals vaccinated with 3xBNT162b2 (PPP) or Coronavac-Coronavac-BNT162b2 (CCP) schedules. However, CCP sera showed 2.3-fold higher neutralization against XBB.1.5 than FWI and PPP sera. This study provides new insights into the differences between BA.2 and BA.5-derived variants, leading to their eventual outcompetition. Our analysis offers important evidence regarding the balance between infectivity and antigenic escape that drives the evolution of second-generation SARS-CoV-2 variants in the population.
- ItemSeroprevalence study of infection with influenza A (H1N1)pdm09 virus in San Felipe Town, Chile(2013) Olea, Andrea; Fasce, Rodrigo; Aguilera, Ximena; Oliva, Otavio; Muñoz, Sergio; García, Maritza; Pedroni, Elena; Nájera, Manuel; Cerda, Jaime; Abarca Villaseca, Katia; Guerrero, Andrea; Bustos, Patricia; Mora, Judith; Vega, Jeanette; Mccarron, Meg; Widdowson, Marc-Alain; Castillo, E. R.
- ItemSurveillance System for Infectious Diseases of Pets, Santiago, Chile(2009) Lopez, Javier; Abarca, Katia; Cerda, Jaime; Valenzuela, Berta; Lorca, Lilia; Olea, Andrea; Aguilera, XimenaPet diseases may pose risks to human health but are rarely included in surveillance systems. A pilot surveillance system of pet infectious diseases in Santiago, Chile, found that 4 canine and 3 feline diseases accounted for 90.1% and 98.4% of notifications, respectively. Data also suggested association between poverty and pet diseases.