Browsing by Autor "Cathal Mills"

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SARS-CoV-2 sero-surveillance after the first and second waves of the epidemic in Panama
(2025) Carlos Lezcano-Coba; Josefrancisco Galué; Charles Whittaker; Cathal Mills; Rodrigo de Antonio; Xavier Saenz-llorens; Luis Rivera; Xacdiel Rodríguez; Danilo Franco; Arturo Rebollón
Abstract Introduction In the context of the ongoing global SARS-CoV-2 pandemic and potential future viral epidemics, seroepidemiological studies are essential for understanding epidemic dynamics. Panama, a country with a strategic geographic position that serves as a regional hub for international travel and commerce. As such, understanding local transmission patterns is critical for developing evidence based on interventions that can effectively anticipate and mitigate emerging viral threats. Methodology We conducted a population-based cross-sectional study in the provinces of Panamá and Panamá Oeste, targeting the 10 townships with the highest cumulative COVID-19 incidence. A multi-stage cluster sampling strategy was employed using the 2010 National Housing Framework. The first survey was conducted from November 30 to December 4, 2020. A follow-up survey was carried out from June 14 to July 10, 2021, to assess seroconversion and seroreversion. Serum samples were analyzed using two electrochemiluminescence immunoassays (Cobas and Vitros) to detect SARS-CoV-2-specific IgG, IgM, and IgA. We estimated the effective reproduction number (Rt) and fitted modified Poisson regression models to identify risk factors associated with seropositivity. Results A total of 2198 participants were recruited in the first round, and 547 were successfully followed up in the second round. SARS-CoV-2 seroprevalence increased from 24.7% (95% CI: 23.0–27.0%) in the first round to 66.2% (95% CI: 62.0 - 70.0%) in the second. The seroconversion rate was 42.9% (95% CI: 38.0 - 47.0%), while seroreversion was rare (0.9%; 95% CI: 0.3 - 2.0%). The most parsimonious multivariable model identified Indigenous ethnicity, contact with a confirmed case, cohabiting with an infected household member, and prior COVID-19 diagnosis as significant risk factors for seropositivity. In contrast, higher education, belonging to other ethnic groups, and consistent mask use at work were protective factors. Conclusions SARS-CoV-2 transmission persisted in Panama despite strict public health interventions. Household transmission, particularly among Indigenous and socioeconomically vulnerable populations, was a major driver of infection. Higher education and adherence to preventive behaviors emerged as protective factors. These findings emphasize the importance of targeted, equity focused strategies to strengthen epidemic control in Panama and comparable settings.
The Role of Climate Change in the Expansion of Dengue
(2025) Rafael Cesário de Abreu; I. Fernández; Swapnil Mishra; Bernardo Gutierrez; Rhys Inward; Cathal Mills; Eduardo Ortíz; Leonardo Soares Bastos; Laís Picinini Freitas; Luiz Max Carvalho
Abstract Climate change-related weather and extreme events are increasing in intensity and frequency, affecting infectious disease transmission globally. Dengue, a climate-sensitive vector-borne disease, to which over half the world’s population is at risk of infection, has expanded its geographical range over recent decades. The 2023/24 season marked the largest ever dengue outbreak year in the Americas, coinciding with the hottest year on record in the Americas. Here, we use statistical models to investigate the Brazil 2023/24 dengue season and attribute how anthropogenic climate change impacted it. We analyze >20 years of dengue data across >5000 municipalities and find that observed temperature anomalies in municipalities of southern Brazil pushed those locations into optimal thermal conditions for dengue transmission. In contrast, in northern Brazil, 2023/24 temperatures became too high for effective transmission, resulting in lower dengue incidence compared to a counterfactual scenario without anthropogenic climate change. We test the generalizability of our model to high altitude areas in Mexico, where dengue has been expanding. Our work empirically demonstrates how a climate-change-related temperature anomaly led to the range expansion and growth of dengue across variable ecological and socio-economic settings, with implications for preparedness, adaptation, mitigation, and resilience planning.