Epidemias en la actualidad: de cómo los modelos matemáticos y estadísticos permiten entenderlas, aún a profesionales "adversos" a ellos / Mathematical models to understand pandemics

Since the declaration of SARS CoV-2 pandemic, we have witnessed an accelerated increase in new cases, frequently associated with the need for intensive care and mechanical ventilation. In parallel, we have been invaded by many experts in the press and who expose their knowledge on the behavior of epidemics who use concepts that are not always well understood by the medical community. Some concepts should be knowledgeable to understand the epidemic spread. First, the epidemic spread description is not modeled with an exponential curve, but rather with a Gompertz curve. Second, a gamma curve describes the period of contagiousness. Third, the contagion magnitude or rate can be calculated and modeled. Explaining these mathematical concepts in a simple and graphic way will allow readers to understand better what is happening with the current pandemic.

Análisis crítico de la baja tasa de donación de órganos en Chile / Critical analysis of the low organ donation rates in Chile

The highest organ donation rate in Chile was 10 donors per million population in 2017, which is low compared with other countries. Local experts attribute the low rate to population's lack of education and generosity, distrust in procurement/allocation system, inadequate legislation and insufficient encouraging campaigns, although without much empirical support: None of the countries from the OECD is also an organ donation leader. Latin Americans who migrate to Spain improve their donation rates, suggesting that the possible explanation is trust in the system where personalities do not have fast access to organs and common people do not have a sense of inaccessibility. Legislation changes in Chile did not have the expected results. Mega campaign did not reduce family refusal, but increased actual donors, probably due to health personnel sensitization. Real problems are inefficiencies in search and procurement processes, because procurement coordinators do not have enough time, dedication or priority to detect possible donors. Eighty seven percent of the latter are not notified to the procurement coordinator. Also, the services that care for possible donors are not adequately aligned. Procurement nurses do not have enough empathy or communication abilities and do not fulfil the professional profile required by the national coordination entity, which is unable to demand for results. The management of procurement coordinators should be improved, and their operational limitations should be visualized. Tools should be provided to the national agency in charge of organ procurement to have more political influence and credibility. Information technologies could ease warns, control and standardize, in real time, the procurement process.

Diseño de una propuesta de protocolo de estandarización y gestión de calidad para el proceso de procuramiento de órganos / Proposal of a management and standardization protocol for organ procurement in Chile

Background: Organ donation rates for transplantation are low in Chile and there is a paucity of a technical-structured-normalized procurement process. Aim: To design a protocol to standardize the organ procurement process based on the Chilean reality. Material and Methods: After a first phase of bibliographic reviews and analyzing de Chilean legislative and normative frame, a proposal was elaborated in collaboration with five expert coordinators. In the second phase, two Delphi rounds with the local coordinators of the organ procurement centers were carried out. Their responses were analyzed and the stages and criteria to standardize the organ procurement process were determined. Results: The expert defined organ procurement process, validated by local coordinators, comprised nine stages and 36 criteria. The expert opinion coincidence was high and significant (Cronbach's alpha > 0.8, p < 0.01). Conclusions: The protocol describing the procurement process, constructed and validated by experts, will allow to standardize a clinical protocol contributing to a successful national organ procurement.

El sinsabor que deja el mejor año en la donación de órganos para trasplante en Chile / Analysis of organ donation for transplantation in Chile during 2017

Background: In October 2016, television stations began a campaign to increase organ donation rates. During the months that followed, a sustained increase in donation rate was observed, reaching 10 per million people. Health authorities considered that this increase was a consequence of an improvement in the search and maintenance of potential donors and TV executives considered that is was due to a reduction in organ donation refusal by relatives of potential donors. Aim: To analyze the year after the TV campaign and determine its relative effect in the improvement of effective organ donation for transplantation. Material and Methods: Monthly figures of donors published on the websites of the National Transplant Corporation and the Ministry of Health and the historical figures for the 2013-2016 period were analyzed. Using this information, the expected behavior was modeled for the number of expected donors for the year 2017 and expected family refusal rates. Results: We found that the number of effective donors for 2017 did not differ substantially from the estimation and that the apparent substantial increase in the rate of organ donation was due to a marked but transitory reduction in the rate of donation refusal by relatives of potential donors. Conclusions: The whole process leading to effective donation should we reanalyzed. New strategies, such as information technologies should be incorporated to improve the detection and management of potential donors. The TV campaign, although successful, was very expensive and very difficult to sustain over time.

Vigilancia de influenza en Chile: 2010 / Influenza surveillance in Chile: 2010

Se analizó el comportamiento de la influenza en el 2010, a través de los componentes de la vigilancia. Desde la semana epidemiológica (SE) 32 aumenta la notificación de ETI en los centinela, con un máximo de casos en la SE 37 (tasa 80 por 105), inferior a 2009. Este aumento coincide con el alza de las consultas respiratorias (especialmente infecciones respiratorias agudas altas e influenza) que llega a 43 por ciento en la SE 36. Destaca la cocirculación de influenza AH1N1 (2009) y H3N2, con predominio de esta última y un máximo en la SE 36. La gravedad (hospitalizaciones por infecciones respiratorias agudas graves y fallecidos) fue menor que en 2009 y se concentró en los casos de H3N2. El aumento observado el 2010 fue de intensidad elevada, de carácter epidémico, y se desplazó a los meses de agosto-septiembre. Se requiere mantener y reforzar los componentes de la vigilancia influenza en el actual período pospandémico.

It was analyzed the 2010 influenza behaviour through surveillance components. Since epidemiologic week (EW) 32, influenza like disease notification increases in sentinel centers, with a maximum of cases on EW 37 (rate of 80 per 105), less than2009. This increase coincide with the rise in respiratory hospital visits (especially upper acute respiratory infections) reaching 43 percent on EW 36. it is registered co-circulation of influenza AH1N1 (2009) and H3N2, the last prevailing over the first one anda maximum on EW 36. Severity (severe acute respiratory infections hospitalizations and deaths) was lower than 2009 and was concentrated in H3N2 cases. The observed increase in 2010 was of high intensity, epidemic nature and shifted to August-September. It is required maintaining and reinforcing influenza surveillance components, in the current pos-pandemic period.

Vigilancia epidemiológica de la enfermedad por hantavirus en los años 2009 y 2010 / Epidemiologic surveillance of hantaviral disease between 2009 and 2010

En Chile es la variedad Andes del hantavirus la que provoca el síndrome cardiopulmonar. El reservorio es el roedor silvestre Oligoryzomys longicaudatus y su hábitat se extiende desde el sur de la Región de Atacama a la Región de Magallanes. Durante los años 2009 y 2010 se confirmaron 35 y 61 casos de síndrome cardiopulmonar por hantavirus, cifra sobre lo esperado para el año 2010, en relación al quinquenio anterior. La letalidad alcanzó en el período a un 32 por ciento. La incidencia en el 2010 fue de 0,35 por 100.000 habitantes. El mayor el riesgo se mantiene en las regiones del sur del país. Sin embargo, se observó un número de casos sobre lo esperado en 2 regiones del centro-sur del país, las que fueron afectadas por el terremoto de 2010. La alta letalidad de esta enfermedad requiere mantener la detección y hospitalización precoz en los casos sospechosos de hantavirus a través de la capacitación a los equipos de salud y realizar campañas de prevención periódica dirigidas a la población y grupos de mayor riesgo.

In Chile, Andes strain causes hantavirus cardiopulmonary syndrome. The reservoir is the wild rodent Oligoryzomys longicaudatus and its habitat extends from south of Atacama region to Magallanes region. During 2009 and 2010, 35 and 61 cases of hantavirus cardiopulmonary syndrome were confirmed, a figure above the expected for 2010 compared to theprevious five years. Lethality reached 32 percent in this period. Incidence in 2010 was 0.35 per 100,000 inhabitants. The greater risk remains in the southern regions of the country. However, a number of cases more than expected were observed in 2 regions in south-central portion of the country, which were affected by the earthquake of 2010. High lethality level of thisdisease requires maintaining early detection and hospitalization in suspected cases of hantavirus through health teams training and conducting periodic prevention campaigns focused at the population and risk groups.

Vigilancia epidemiológica de zoonosis y enfermedades transmisibles por vectores: Chile 2009-2010 / Epidemiologic surveillance of zoonosis and vector-borne diseases: Chile 2009-2010

Se presenta la situación epidemiológica de las zoonosis de mayor importancia en salud pública en Chile y que están incluidas en el Decreto 158/04 como enfermedades de notificación obligatoria. Se hace el análisis de las zoonosis y enfermedades transmitidas por vectores de los años 2009 y 2010, utilizando las bases de datos ENO del Departamento de Estadísticas e Información en Salud (DEIS), MINSAL, y los informes periódicos generados en el Departamento de Epidemiología. Los resultados indican que las zoonosis muestran una tendencia decreciente. Brucelosis es una enfermedad de baja presentación, desatendida y posiblemente subnotificada. En triquinosis se observan fundamentalmente brotes en la zona centro-sur del país especialmente en la población masculina. Carbunco se manifiesta como una enfermedad de muy baja endemia y en el único caso de estos dos últimos años se manifestó la forma cutánea de la enfermedad. Leptospirosis: destaca la presentación de casos en hombres en un 100%. Hidatidosis destaca por mantener su incidencia relativamente alta y un importante número en menores de 10 años. Dengue: persiste la circulación viral en Isla de Pascua y a nivel continental se presentan casos importados que provienen especialmente de Centro y Sudamérica. Malaria: sólo existen casos importados y tendencia decreciente, posiblemente por subnotificación.

Due to the success in the elimination of measles, rubella and CRS reached in the Americas, PAHO requested the verification of the elimination of these diseases in the countries of the region. Chile ratified by means of a resolution a National Committee of Experts, which revised the information provided by the technical teams in the following components: Epidemiology of measles, rubella and CRS; quality of the surveillance; molecular epidemiology; sustainability of the Immunization Program and cohorts of vaccinated population. The information gathered from different sources allowed to integrate the evidence provided and to determine if the data were valid, complete, representatives and consistent. In this paper we describe thecertification steps and the information evaluated by the ad-hoc national committee. Their conclusions will be ratified by the International Committee, which will certify if Chile fulfills the criteria for elimination, a process that is expected to end during December 2011.