Browsing by Author "Neira, Víctor"

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    Cross-species transmission and PB2 mammalian adaptations of highly pathogenic avian influenza A/H5N1 viruses in Chile
    (2023) Pardo Roa, Catalina; Nelson, Martha I.; Ariyama, Naomi; Aguayo, Carolina; Almonacid Cárdenas, Leonardo Iván; Muñoz, Gabriela; Navarro, Carlos; Ávila, Claudia; Ulloa, Mauricio; Reyes, Rodolfo; Fuentes Luppichini, Eugenia Lucía Angélica; Mathieu, Christian; Vergara, Ricardo; González, Álvaro; González, Carmen Gloria; Araya, Hugo; Fernández, Jorge; Fasce, Rodrigo; Johow, Magdalena; Medina, Rafael; Neira, Víctor
    H5N1 highly pathogenic avian influenza viruses (HPAIV) emerged in wild birds in Chile in December 2022 and spilled over into poultry, marine mammals, and one human. Between December 9, 2022 – March 14, 2023, a coordinated government/academic response detected HPAIV by real-time RT-PCR in 8.5% (412/4735) of samples from 23 avian and 3 mammal orders. Whole-genome sequences obtained from 77 birds and 8 marine mammals revealed that all Chilean H5N1 viruses belong to lineage 2.3.4.4b and cluster monophyletically with viruses from Peru, indicating a single introduction from North America into Peru/Chile. Mammalian adaptations were identified in the PB2 segment: D701N in two sea lions, one human, and one shorebird, and Q591K in the human and one sea lion. Minor variant analysis revealed that D701N was present in 52.9 – 70.9% of sequence reads, indicating the presence of both genotypes within hosts. Further surveillance of spillover events is warranted to assess the emergence and potential onward transmission of mammalian adapted H5N1 HPAIV in South America.
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    Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Wild Birds, Chile
    (2023) Ariyama, Naomi; Pardo-Roa, Catalina; Muñoz, Gabriela; Aguayo, Carolina; Ávila, Claudia; Mathieu, Christian; Almonacid Cárdenas, Leonardo Iván; Medina, Rafael; Brito, Barbara; Johow, Magdalena; Neira, Víctor
    In December 2022, highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b virus emerged in Chile. We detected H5N1 virus in 93 samples and obtained 9 whole-genome sequences of strains from wild birds. Phylogenetic analysis suggests multiple viral introductions into South America. Continued surveillance is needed to assess risks to humans and domestic poultry.
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    Novel Avulaviruses in Penguins, Antarctica
    (2017) Neira, Víctor; Tapia, Rodrigo; Verdugo, Claudio; Barriga, Gonzalo; Mor, Sunil; Fei Fan Ng, Terry; García, Victoria; Del Río, José; Rodríguez, Pedro; Medina, Rafael; Briceño, Cristóbal; González Acuña, Daniel
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    Reducing household tuberculosis transmission. A pilot cluster-randomized controlled trial
    (2025) Ruiz-Tagle Seguel, Cinthya Grace; Seguel Araus, Romina Javiera; Villarroel del Pino, Luis A.; Bernales, Margarita; Vargas García, Salvador; Pizarro Ibañez, Alejandra Valentina; Peña, Carlos; Neira, Víctor; García Cañete, Patricia; Allel Henríquez, Kasim Ignacio; Nathavitharana, Ruvandhi R.; Balcells Marty, María Elvira
    Background: The duration of infectiousness following pulmonary tuberculosis treatment initiation remains uncertain. We aimed to assess whether a bundled intervention designed to decrease respiratory exposure was feasible and would reduce new tuberculosis infections in household contacts (HHCs). Methods: We conducted a pilot cluster-randomized controlled trial with a hybrid type 1 effectiveness-implementation design in Santiago, Chile. Random allocation was performed, and two healthcare districts were assigned to the intervention (n=180 HHCs) and one to standard of care (n=149 HHCs). Eligible participants were newly diagnosed pulmonary tuberculosis patients and their HHCs. The intervention included education, mask use, household ventilation, and nightly separation of tuberculosis patients, for two weeks. Intervention adherence was evaluated weekly. Effectiveness was assessed at the individual level with QuantiFERON®-TB Gold Plus (QFT) test conversions in HHCs at 12-week follow-up. Results: Between October 2021 and December 2023, 384 HHCs and 157 tuberculosis patients were enrolled. Overall, 56.3% of contacts were women, with mean age of 34.6 years and a baseline QFT positivity of 32.3%. A total of 216 contacts had negative QFT result at baseline, with 179 (82.9%) completing follow-up. QFT conversions occurred in 11 (12.8%) and 10 (10.8%) HHCs from the intervention and control arms, respectively (incidence risk ratio 1.10, 95% CI 0.71-1.71, p=0.849). Good adherence to the respiratory bundle was reported by 53% of participants on day 7 and 54% on day 14.
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    Reemergence of H3N8 Equine Influenza A virus in Chile, 2018
    (2018) Mena, Juan; Brito, Bárbara; Moreira, Rubén; Tadich, Tamara; González, Igor; Cruces, Jaime; Ortega, Rene; Bakel, Harm; Rathnasinghe, Raveen; Medina Silva, Rafael Andrés; Pizarro‐Lucero, José; Neira, Víctor