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Resumen Introducción: Los casos de sarampión están resurgiendo en muchos países del mundo. Hubo un brote de sarampión importado entre noviembre de 2018 y febrero de 2019 en Chile, lo que generó preocupación entre el público y las autoridades sanitarias. Muchos se preocuparon por la tasa de inmunización contra el sarampión de la población, un factor que se relaciona con la capacidad reproductiva del virus (medida de transmisibilidad de un patógeno). Objetivo: Aquí estimamos el número reproductivo efectivo (Re) de este brote de sarampión. Resultados: Aunque la estimación tiene mucha incertidumbre por el bajo número de casos y la ausencia de mezcla homogénea de la población, encontramos que Re fue aproximadamente 1,5. Discusión y Conclusiones: En consecuencia estimamos que aproximadamente 90,3% de la población tiene inmunidad al sarampión, lo que coincide con las estimaciones del Ministerio de Salud. Estos resultados sugieren que la población chilena ha establecido la inmunidad colectiva contra la introducción de casos importados de sarampión, lo que refleja un manejo preventivo adecuado de esta enfermedad.

The recent outbreak of emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) has been brought to global attention in the search of knowledge about the virus and its pathogenesis The immune response is essential to control and eliminate the infection, however, maladjusted immune responses may result in severe disease fisiopathology Gaining a deeper understanding of the interaction between SARS-CoV-2 and the immune systems of the hosts may help us anticipate the development of persistent pulmonary inflammation and, why not, be the first step to therapeutic success and trying to save more lives In this review, we provide an update on CoV virology and our vision of pathogenesis understanding it from the stages of infection, without forgetting the cytokine storm resulting from the interaction of the virus with ACE2 receptors widely distributed in the body La reciente emergencia de sindrome de distres respiratorio agudo producido por coronavirus 2 (SARS-CoV-2), enfermedad denominada COVID-19 ha traido la atencion mundial a la busqueda de conocimiento sobre este virus y su patogenia La respuesta inmune es esencial para controlar y erradicar la infeccion, sin embargo, las respuestas inmunes descontroladas pueden resultar en la fisiopatologia de la enfermedad grave Lograr una comprension mas profunda de la interaccion entre SARS-COV-2 y el sistema inmune de los huespedes podria ayudar a anticiparnos al desarrollo de una inflamacion pulmonar persistente causada por el SARS-CoV-2, y por que no, ser la puerta de entrada al exito terapeutico e intentar salvar mayor numero de vidas En esta revision, proporcionamos una actualizacion sobre la virologia y nuestra vision de la patogenia, entendiendola desde las fases o etapas de la infeccion, sin olvidar el estallido de citoquinas resultantes de la interaccion del virus con los receptores ACE2 ampliamente distribuidos en el organismo

The SARS-CoV-2 pandemic has become a global health problem causing severe human respiratory infections Countries have had to establish strategies to avoid the collapse of health systems There has been reports describing that the human-to-human transmission is through droplet spread and contact routes as through hands and contaminated surfaces Social distancing, personal protective equipment, hand washing often, and surface disinfection play a fundamental role in disease control Some procedures and situations aerosolize the SARS-CoV-2, so protection measures must be extreme Hard work is underway to develop and implement a vaccine that would provide immunity to the population, but it will take some time Preventive measures must incorporate good epidemiological monitoring that guarantees adequate control of cases and contacts in order to isolate them from the rest of the population, whether hospitalized or at home La pandemia de SARS-CoV-2 se ha convertido en un problema global de salud provocando infecciones respiratorias severas en humanos Los paises han tenido que establecer estrategias para evitar el colapso de los sistemas sanitarios Se ha descrito una transmision de persona a persona facilitada por propagacion de gotitas, manos o superficies contaminadas El distanciamiento fisico, los elementos de proteccion personal, el lavado de manos frecuente y la desinfeccion de superficies cumplen un rol fundamental en el control de la enfermedad Algunos procedimientos y situaciones aerosolizan el SARS-CoV-2 por lo que se deben extremar las medidas de proteccion Se trabaja arduamente para lograr una vacuna que otorgue inmunidad a la poblacion, pero su desarrollo va a tomar algun tiempo Las medidas preventivas deben incorporar una buena vigilancia epidemiologica que garantice el control adecuado de los casos y contactos, con el objeto de aislarlos del resto de la poblacion, ya sea hospitalizados o en sus domicilios

The severity of community acquired pneumonia (CAP) can be evaluated by the PSI and CURB-65 scales. However, it is unknown whether their predictive capacity varies according to the etiology of the disease.To compare the performance of these scales in adults with viral, bacterial, mixed, and no agent detected CAP.We studied 725 patients hospitalized for CAP aged 18 to 95 years (47% females) Urinary S. pneumoniae and Legionella antigens were detected by immuno-chromatography (Binax®). Respiratory viruses and bacteria were detected by PCR in nasopharyngeal smears. The proportions of deaths, admission to the intensive care unit (ICU), and oxygen therapy were compared between mild and non-severe patients defined by PSI (I/II and I-III) and CURB-65 (1 and 1-2), according to the causative agent.Ten percent of patients died. A causative agent was detected in 65%. The proportion of mild and non-severe patients according to PSI and CURB-65, and of deceased patients, admitted to the ICU and with oxygen therapy was similar in the four categories per agent. There were no deaths among non-severe patients with bacterial CAP. However, 6% of patients with CAP caused by virus or without causative agents, died. No deaths occurred among mild patients with bacterial CAP. In viral CAP, no deaths occurred among patients classified as mild only by PSI. The yields of PSI were greater than those of CURB-65 in non-severe patients who died and were admitted to the ICU with bacterial and viral CAP (5 and 14%; 7 and 12% respectively, p = 0.04).The prognostic performance of PSI in CAP varies according to the causative agent in adults. It is higher in non-severe bacterial cases, and superior to CURB-65.

There is always a risk of importing infectious diseases when travelling abroad.To estimate the effective risk of a Chilean of acquiring measles during a travel by countries where measles outbreaks have been reported, considering the present level of immunity in the country.Previously established mathematical models using differential equations were applied to calculate the risk of acquiring measles of people traveling to endemic areas.The probability of acquiring measles of a voyager is 8.11 x 10-8.These estimations help decision making about preventive measures for travelers to endemic measles areas.

Measles cases are reemerging in many countries across the globe. There was an outbreak of imported measles between November 2018 and February 2019 in Chile, raising concern among the public and health authorities. Many were worried about the Chilean measles herd immunity, a factor that relates to the reproductive capacity of the virus (measure of transmissibility of a pathogen).Here we estimate the effective reproductive number (Re) of this measles outbreak.Although the estimate is highly uncertain due to the low number of cases and the absence of homogeneous mixing of the population, we found Re was approximately 1.5.Consequently we estimated about 90,3 % had measles immunity, consistent with administrative estimates from the Ministry of Health. These results suggest the Chilean population has established herd immunity against the introduction of imported measles cases, reflecting adequate preventive management of this disease.

Background Adenovirus serotypes 7, 2 and 1 are the second most common cause of viral acute lower respiratory tract infection (ALRI) requiring hospitalization in Chile. Nosocomial outbreaks have high secondary attack and lethality rates, and call for rapid and specific diagnosis. Objective We compared the results obtained on ALRI specimens by immunofluorescence (IFA) and virus isolation, plus restriction enzyme digestion (RFLP) typing, with universal, species-specific and 7h-specific PCR typing of adenovirus. A second objective was to determine the type of adenovirus implicated in nosocomial infection and nosocomial cross-infection rates. Methods Infants hospitalized for ALRI in the Roberto del Rio Children's Hospital (Santiago, Chile) in 1995–1996 had nasopharyngeal aspirates obtained at admission and tested by IFA and virus isolation. Adenovirus isolates were identified by RFLP. When an index case was identified, samples were collected from contacts for 2 consecutive days and twice weekly thereafter for 2 weeks. Further typing of adenovirus isolates was undertaken with universal, species-specific and 7h-specific PCR performed in 2003 on the stored frozen samples. Results Fifteen index cases of adenovirus and their 65 contacts were identified. The nosocomial secondary attack rate using PCR was estimated as 46%. PCR had a higher sensitivity (98.7%) compared to virus isolation (90%) and IFA (50%) and facilitated identification of adenovirus strains more easily and accurately than RFLP (91.6% versus 55.8%). Fifty-three percent of the contacts had severe outcomes. The case fatality rate was 16.6% and was associated with adenovirus 7h. Conclusions Prompt, rapid and sensitive methods to identify adenovirus infection are necessary, especially for hospital-acquired adenovirus infections, because of their ease of spread and high fatality rate.

Human metapneumovirus (hMPV) has recently been described as a new causal agent of acute low respiratory infection (ALRI) in children. In South America, detection has been reported only in Brazil and Argentina.To detect hMPV in children hospitalized for ALRI in Santiago, Chile.Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect N gene of hMPV in 182 nasopharyngeal aspirates that were negative for common respiratory viruses, obtained from children hospitalized for ALRI during 2003.Ten samples (5.4%) were positive, most of them detected during spring months.Since hMPV was detected among infants with ALRI in Santiago, further studies on their prevalence should be done in South America.

Electropherotypes of human rotavirus from stool samples of hospitalized and ambulatory infants with acute diarrhea were analysed. Thirty-two different electropherotypes were observed in 142 cases in which the viral genome RNA was characterized. The seasonal distribution of the electropherotypes, from 1979 to 1981, showed that the same electropherotypes were detected throughout the period of study while others were found only occasionally. Electropherotypes were also analyzed depending on whether the patient from whom they had been obtained required hospitalization or was treated at home. The analysis shows that the electropherotypes were equally distributed in both groups of patients.

An outbreak of chickenpox that occurred at the Burns Repair Surgery Unit, Department of Children's Surgery, Hospital R. del Río, between June and November, 1975, is reported. 27 cases of burned children were studied, including analysis of correlations of the stages and outcome of the disease (varicela), the trauma (burns) and the graft (repair surgery). As a result, the authors emphasize the following findings: 1. Burns and their repair are not aggravating factors for varicella. In a small number of cases the exanthema looked more confluent in the graft surgical areas and in the first degree burns healing spontaneously. 2. Usually there was an uneventful outcome of graft repair surgery on a varicella patient, either during the incubation period, the acme or the convalescence. 3. The fact that the outmost intensity of secondary viremia of varicella occurs before the onset of exanthemia, that is, during the late incubation period, is confirmed.

RESUMEN Se estudio la etiologia viral de algunas dia­rreas infantiles en el verano de 1973 en Santiago. Se hizo coprocultivo de 88 nifios con diarrea (Grupo A), de 50 nifios controles sanos {Grupo B) y de 40 nifios contactos de los enfermos (Gru­po C). Se tituld anticuerpos siricos del Grupo A en muestras pareadas. Alrededor del 80% de los nihos era menor de dos anos en los Gru­pos A y B, mientras que un 90% de los nihos era mayor de 2 anos en el Grupo C. La tasa de aislamiento viral fue de 23 % para los nifios con diarrea, 16% para los controles y 20% para los contactos. En los lactantes de 6 meses a un ano de edad, se obtuvo tasas de ais­lamiento de 35% para el Grupo A y 10% para el Grupo B. El andlisis de los virus aislados en el coprocultivo senalo predominancia de virus ECHO (tipos 6, 7, 11 y 19) en los nifios con diarrea, especialmente ECHO tipo 6. Otros virus aisla­dos fueron: Coxsackie B (tipos 3 y 5), Coxsa­ckie A y virus "no tipificable", pero estos se dis-tribuyen en forma equivalente