Retrospective Analysis of Severe Dengue by Dengue Virus Serotypes in a Population with Social Security, Mexico 2023.

BACKGROUND: Risk factors for severe dengue manifestations have been attributed to various factors, including specific serotypes, sex, and age. Mexico has seen the re-emergence of DENV-3, which has not circulated in a decade. OBJECTIVE: To describe dengue serotypes by age, sex, and their association with disease severity in dengue-positive serum samples from epidemiological surveillance system units. MATERIALS AND METHODS: A descriptive analysis was conducted to evaluate the frequency of dengue severity by sex, age, disease quarter, geographical location, and dengue virus serotypes. The study was conducted using laboratory samples from confirmed dengue cases through RT-qPCR from the epidemiological surveillance laboratory network of the Mexican Social Security Institute, Mexico. Simple frequencies and proportions were calculated using the z-test for proportional differences between groups. Bivariate analysis with adjusted Chi2 was performed, and binary logistic regression models were constructed using the forward Wald method considering the model's predictive capacity. The measure of association was the odds ratio, with 95% confidence intervals. Statistical significance was set to an alpha level of <0.05. RESULTS: In 2023, 10,441 samples were processed for dengue RT-qPCR at the IMSS, with a predominance of serotype DENV-3 (64.4%). The samples were mostly from women (52.0%) and outpatient cases (63.3%). The distribution of dengue severity showed significant variations by age, with a lower proportion of severe cases in young children and a higher proportion in the 5- to 14-year-old group. Hospitalizations increased significantly with severity. Warm regions had more cases overall and severity. Cases were most frequent from July to September. While DENV-2 was associated with severity, DENV-4 was not. Binary regression identified higher risk in women, age extremes, and DENV-2, with an overall predictive model of 58.5%. CONCLUSIONS: Women, age groups at the extremes of life, and the DENV-2 serotype presented severe risk of dengue in a population with social security in Mexico during 2023.

Effectiveness of a diagnostic algorithm for dengue based on an artificial neural network.

Introduction: Dengue is a disease with a wide clinical spectrum. The early identification of dengue cases is crucial but challenging for health professionals; therefore, it is necessary to have effective diagnostic instruments to initiate timely care. Objective: To evaluate the effectiveness of an algorithm based on an artificial neural network (ANN) to diagnose dengue in an endemic area. Methods: A single-center case-control study was conducted in a secondary-care hospital in Ciudad Obregón, Sonora. An algorithm was built with the official operational definitions, which was called the "direct algorithm," and for the ANN algorithm, the brain.js library was used. The data analysis was performed with the diagnostic tests of sensitivity, specificity, positive predictive value (ppv), and negative predictive value (npv), with 95% confidence intervals and Cohen's kappa index. Results: A total of 233 cases and 233 controls from 2022 were included. The ANN presented a sensitivity of 0.90 (95% CI [0.85, 0.94]), specificity of 0.82 (95% CI [0.77, 0.87]), npv of 0.91 (95% CI [0.87, 0.94]) and ppv of 0.81 (95% CI [0.76, 0.85]) and a kappa of 0.72. The direct algorithm had a sensitivity of 0.97 (95% CI [0.94, 0.99]), specificity of 0.96 (95% CI [0.92, 0.98]), npv 0.97 (95% CI [0.94, 0.98]), ppv 0.96 (95% CI [0.93, 0.98]) and kappa 0.93. Conclusions: The direct algorithm performed better than the ANN in the diagnosis of dengue.

Impact of vaccination on infection or death from COVID-19 in individuals with laboratory-confirmed cases: Case-control study.

OBJECTIVES: The objective of this study is to estimate the effectiveness of COVID-19 vaccines in people treated within the social security system whose vaccination status was reported to the epidemiological surveillance system. STUDY DESIGN: Case-control study. METHODS: This was a case-control study conducted. The records of individuals with suspected cases of COVID-19 registered in the epidemiological surveillance system between February 1 and June 30, 2021, were studied. RT-qPCR was performed to determine SARS-CoV-2 infection; those with a positive result were considered cases, and those with a negative result were considered controls. The ratio between cases and controls was 1:1.3. The crude and adjusted vaccine effectiveness was considered the prevention of symptomatic infection and death and calculated as the difference between the dose and the risk, with a survival analysis among vaccinated people. RESULTS: A total of 94,416 individuals were included, of whom 40,192 were considered cases and 54,224 controls; 3,781 (4.00%) had been vaccinated against COVID-19. Vaccination also proved to be a protective factor against COVID-19, especially in the population who received a second dose (OR = 0.31; 95% CI 0.28-0.35). With the application of the vaccine, there was a protective effect against mortality (OR = 0.76; 95% CI 0.66-0.87). Disease prevention was higher for the BNT162-2 mRNA vaccine (82%) followed by the ChAdOx1 vaccine (33%). In the survival analysis, vaccination provided a protective effect. CONCLUSIONS: There was a positive impact of vaccines for the prevention of symptomatic COVID-19, with a second dose generating greater efficacy and a reduction in deaths.

[Monkeypox: the other pandemic, the other challenge]. / Viruela símica: la otra pandemia, el otro reto.

Since the emergence of monkeypox in Europe, this disease has gradually spread throughout the rest of the world. In Mexico, epidemiological notices have been issued with the main guidelines to follow in terms of epidemiological surveillance and official figures have been published regularly on a microsite weeks after the first cases. These sources of information were reviewed and analyzed, based on which observations are issued, in addition to other relevant publications on the subject, with the interest of reinforcing the surveillance of this disease in the country.

Desde el surgimiento de la viruela símica en Europa la enfermedad se ha extendido paulatinamente por el resto del mundo. En México se han emitido avisos epidemiológicos con las principales pautas a seguir en materia de vigilancia epidemiológica y publicado las cifras oficiales de forma regular en un micrositio semanas después de los primeros casos. Se revisaron y analizaron dichas fuentes de información, con base en las cuales se emiten observaciones, además de otras publicaciones relevantes del tema, con el interés de reforzar la vigilancia de esta enfermedad en el país.

Omicron-BA.1 Dispersion Rates in Mexico Varied According to the Regional Epidemic Patterns and the Diversity of Local Delta Subvariants.

PURPOSE: The Omicron subvariant BA.1 of SARS-CoV-2 was first detected in November 2021 and quickly spread worldwide, displacing the Delta variant. In this work, a characterization of the spread of this variant in Mexico is presented. METHODS: The time to fixation of BA.1, the diversity of Delta sublineages, the population density, and the level of virus circulation during the inter-wave interval were determined to analyze differences in BA.1 spread. RESULTS: BA.1 began spreading during the first week of December 2021 and became dominant in the next three weeks, causing the fourth COVID-19 epidemiological surge in Mexico. Unlike previous variants, BA.1 did not exhibit a geographically distinct circulation pattern. However, a regional difference in the speed of the replacement of the Delta variant was observed. CONCLUSIONS: Viral diversity and the relative abundance of the virus in a particular area around the time of the introduction of a new lineage seem to have influenced the spread dynamics, in addition to population density. Nonetheless, if there is a significant difference in the fitness of the variants, or if the time allowed for the competition is sufficiently long, it seems the fitter virus will eventually become dominant, as observed in the eventual dominance of the BA.1.x variant in Mexico.

[Serenity and objectivity in the face of severe childhood hepatitis: the diagnostic challenge]. / Serenidad y objetividad ante la hepatitis grave infantil: el reto diagnóstico.

The appearance of acute hepatitis of unknown aetiology in children has set off alarms in the World Health Organization and in member countries; identifying it and studying it lay out a diagnostic challenge for first-contact medical personnel and especially for pediatricians of Mexico, as well as for the coordination of care in health services. The international outlook and an analysis of the clinical manifestations are described, as well as key points for the identification and an observation of the samples that are requested for their study in Mexico.

La aparición de la hepatitis aguda infantil de etiología desconocida ha hecho que suenen las alarmas en la Organización Mundial de la Salud y en los países miembros; su identificación y estudio plantean un reto diagnóstico para el personal médico de primer contacto y en especial para los pediatras del país, así como para la coordinación de la atención en los servicios de salud. Se describe el panorama internacional y un análisis de las manifestaciones clínicas y los puntos clave para su identificación, así como una observación a las muestras que se solicitan para su estudio en México.

Predict the incidence of Guillain Barré Syndrome and arbovirus infection in Mexico, 2014-2019.

The Dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV) virus infections have been linked to Guillain-Barré syndrome (GBS). GBS has an estimated lethality of 4% to 8%, even with effective treatment. Mexico is considered a hyperendemic country for DENV due to the circulation of four serotypes, and the ZIKV and CHIKV viruses have also been circulating in the country. The objective of this study was to predict the number of GBS cases in relation to the cumulative incidence of ZIKV / DENV / CHIKV in Mexico from 2014 to 2019. A six-year time series ecological study was carried out from GBS cases registered in the Acute Flaccid Paralysis (AFP) Epidemiological Surveillance System (ESS), and DENV, ZIKV and CHIKV estimated cases from cases registered in the epidemiological vector-borne diseases surveillance system. The results shows that the incidence of GBS in Mexico is positively correlated with DENV and ZIKV. For every 1,000 estimated DENV cases, 1.45 GBS cases occurred on average, and for every 1,000 estimated ZIKV cases, 1.93 GBS cases occurred on average. A negative correlation between GBS and CHIKV estimated cases was found. The increase in the incidence of GBS cases in Mexico can be predicted by observing DENV and ZIKV cases through the epidemiological surveillance systems. These results can be useful in public health by providing the opportunity to improve capacities for the prevention of arbovirus diseases and for the timely procurement of supplies for the treatment of GBS.

Laboratory-confirmed SARS-CoV-2 reinfection in the population treated at social security.

The scientific community has questioned whether reinfection with SARS-CoV-2 is possible. Gradually, cases of reinfection have been documented. In Mexico, people with SARS-CoV-2 reinfection have not been officially identified. To allow a retrospective investigation of patients with PCR-confirmed SARS-CoV-2 and to identify how reinfected with this virus occurs in a population that requires medical attention. A retrospective search of the epidemiological surveillance system was performed to identify people who met the clinical criteria based on laboratory diagnosis of SARS-CoV-2 and temporality to identify cases of reinfection. Clinical information was collected from clinical records. Seven people with two separate COVID-19 events were identified in medical units in Quintana Roo, Mexico between April and December 2020. The overall median interval between the two events was 156 days (61-191 days). Six people were health workers, and one was a member of the general population. This is one of the first reports of reinfection in health personnel in Mexico, revealing that the frequency of reinfection is low among positive cases and that the interval between infection episodes was three months. There are several scenarios in the natural history of the disease that must be considered based on adequate anamnesis with a clinical-epidemiological approach to determine the correct diagnostic category.

Pneumothorax due to COVID-19: Analysis of case reports.

Cases of pneumothorax/pneumomediastinum have been reported in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, the time to onset and hospital stay have rarely been studied. Coronavirus disease 2019 (COVID-19) patients with these complications are described to determine the time to onset, associated comorbidities, and location and duration of pneumothorax. A search in PubMed yielded simple frequencies and a bivariate analysis of deaths. There were 113 confirmed cases in 67 articles. The median time from the date of hospital admission to the presence of pneumothorax was 8 days. Right hemithorax was the most frequent form of pneumothorax. Almost half of the patients required intubation for invasive mechanical ventilation. Although the frequency of this phenomenon was not high among hospitalized patients with confirmed SARS-CoV-2, it was high among those who developed acute respiratory distress syndrome (ARDS). This study contributes to the literature because it presents a large number of patients who developed pneumothorax after admission, which was characterized by clinical deterioration (dyspnea, tachypnea, pleuritic chest pain, and subcutaneous emphysema) and low oxygen saturation levels. Pneumothorax/pneumomediastinum is recommended as a differential diagnosis, even without considering the presence of chronic pulmonary comorbidities or invasive mechanical ventilation.

Enfermedad de Creutzfeldt-Jakob / Creutzfeldt-Jakob disease

Resumen: La enfermedad de Creutzfeldt-Jakob es una afección neuroselectiva y neurodegenerativa, de curso fatal, poco frecuente, que representa un desafío para el diagnóstico clínico. Se comunica el caso de un paciente de 52 años de edad con antecedente de ingesta de mamíferos silvestres durante su vida, con cuadro de disminución de la agudeza visual, demencia rápidamente progresiva, mioclonías, movimientos anormales y disfunción motora; con estudios auxiliares de diagnóstico diferencial dentro de parámetros normales y la determinación de la proteína TAU reactiva.

Abstract: Creutzfeldt-Jakob disease is a neuroselective and neurodegenerative illness, with fatal course, which is rare and represents a challenge for clinical diagnosis. This paper reports the case of a 52-year-old male with a history of ingestion of wild mam- mals during his life, with a picture of diminished visual acuity, rapidly progressive dementia, myoclonus, abnormal movements and motor dysfunction; with auxiliary studies of differential diagnosis within normal parameters and the determination of reactive TAU protein.

Zika virus: Epidemiological surveillance of the Mexican Institute of Social Security.

INTRODUCTION: At the end of 2015, the first cases of Zika were identified in southern Mexico. During 2016, Zika spread as an outbreak to a large part of the country's coastal zones. METHODOLOGY: The Zika epidemiological surveillance system records cases with clinical symptoms of Zika virus disease (ZVD) and those confirmed by means of a reverse polymerase chain reaction (RT-PCR) assay. This report includes the suspected and confirmed cases from 2016. Incidence rates were estimated by region and in pregnant women based on the proportion of confirmed cases. RESULTS: In total, 43,725 suspected cases of ZVD were reported. The overall incidence of suspected cases of ZVD was 82.0 per 100,000 individuals and 25.3 per 100,000 Zika cases. There were 4,168 pregnant women with suspected symptoms of ZVD, of which infection was confirmed in 1,082 (26%). The estimated incidence rate of ZVD for pregnant women nationwide was 186.1 positive Zika cases per 100,000 pregnant women. CONCLUSIONS: The incidence of Zika in Mexico is higher than that reported previously in the National System of Epidemiological Surveillance. Positive cases of Zika must be estimated and reported.

[Association of Notified Cases and Treatment Success Rates in Pulmonary Tuberculosis].

Background: Tuberculosis has long been recognized as a public health problem in large cities. The goals of the "Stop TB" strategy of the WHO specifically promote its study at the subnational level. Therefore, we aimed to describe the state of pulmonary tuberculosis (PTB) at the municipality level in Mexico. Methods: We obtained data on new cases of PTB and treatment success rates (TSRs) per municipality from each state in Mexico, reported by the Mexican Social Security Institute to the National Epidemiological Surveillance System during 2013. Regression model was used to quantify associations between PTB and TSR by the municipality. Results: We included 4090 cases of PTB distributed in 432 municipalities. There were 121 municipalities with TSRs < 85%. Lower TSRs were associated with older age, male sex, and comorbidities. Conclusions: Results suggest a negative outcome of PTB treatment in patients with HIV and in those with malnutrition. The number of reported cases by the municipality was not associated with a negative treatment outcome.

[The fourth horseman: The yellow fever]. / El cuarto jinete: fiebre amarilla.

Dengue virus three, Chikunguya and Zika have entered the national territory through the south of the country. Cases and outbreaks of yellow fever have now been identified in the Americas where it threatens to expand. Although Mexico has a robust epidemiological surveillance system for vector-borne diseases, our country must be alert in case of its possible introduction into the national territory. This paper presents theoretical assumptions based on factual data on the behavior of yellow fever in the Americas, as well as reflections on the epidemiological surveillance of vector-borne diseases.

El dengue virus tres, el Chikunguya y el Zika han entrado al territorio nacional por el sur del país. Actualmente se han identificado casos y brotes de fiebre amarilla en el continente americano, donde amenaza con expandirse. Si bien México cuenta con un robusto sistema de vigilancia epidemiológica de enfermedades transmitidas por vector, nuestro país deberá estar alerta en caso de su posible introducción al territorio nacional. En el presente documento se expresan supuestos teóricos a partir de datos factuales del comportamiento de la fiebre amarilla en el continente americano, así como reflexiones a la vigilancia epidemiológica de las enfermedades transmitidas por vector.

Association of Pulmonary Tuberculosis and HIV in the Mexican Institute of Social Security, 2006-2014.

BACKGROUND: Tuberculosis and HIV remain a public health problem in developed countries. The objective of this study was to analyze the incidence trends of pulmonary TB and HIV comorbidity and treatment outcomes according to HIV during the period 2006 to 2014 in the Mexican Institute of Social Security. METHODS: Analyzed data from this registry including pulmonary tuberculosis patients aged 15 years and older who had been diagnosed during the years 2006 to 2014 in the Mexican Institute of Social Security. The outcomes that we use were incidents rate, failure to treatment and death. Regression models were used to quantify associations between pulmonary tuberculosis and HIV mortality. RESULTS: During the study period, 31,352 patients were registered with pulmonary tuberculosis. The incidence rate observed during 2014 was 11.6 case of PTB per 100,000. The incidence rate for PTB and HIV was 0.345 per 100,000. The PTB incidence rate decreased by 0.07%, differences found in the PTB incidence rate by sex since in women decreased by 5.52% and in man increase by 3.62%. The pulmonary TB with HIV incidence rate decreased by 16.3% during the study period (In women increase 4.81% and in man decrease 21.6%). Analysis of PTB associated with HIV by age groups revealed that the highest incidence rates were observed for the 30 to 44 years old group. Meanwhile, the highest incidence rates of PTB without HIV occurred among the 60 and more years old individuals. We did not find statistically significant differences between treatment failure and PTB patients with HIV and without HIV. The treatment failure was associated with sex and the region of the patient. We found a strong association between HIV and the probability of dying during treatment. Our data suggested that patients suffering from both conditions (PTB and HIV) have no difference in the probability of failure of treatment contrary to other reports. Hypotheses to this is adherence to tuberculosis treatment with people living with HIV/AIDS, detection of PTB in patients suffering from HIV/AIDS or PTB patients on antiretroviral therapy were more likely to have successful treatment outcomes than those not on antiretroviral treatment. We have found that PTB and HIV increases the probability of dying during treatment compared to the cases of PTB without HIV, consistent with published other study HIV increases the mortality rates associated with PTB. CONCLUSIONS: No association between pulmonary tuberculosis with HIV and treatment failure was observed, but pulmonary tuberculosis and HIV increases the probability of dying during treatment compared to the pulmonary tuberculosis cases without HIV.

[Clinical features of Zika virus]. / Manifestaciones clínicas del virus Zika.

BACKGROUND: Zika virus was introduced to the country and threatens to spread, so the health personnel must be able to identify the disease and face an operational definition given case; in this review the clinical manifestations of probable cases of Zika of the last five years were described. METHODS: A search was performed in Google Scholar and PubMed with "Zika". He settled for a database and obtained simple frequencies and calculated the limits for proportions with an alpha of 0.05 through test Wilson. RESULTS: 109 probable cases of fever came together by Zika, the clinical manifestations was heterogeneous, with predominant involvement to musculoskeletal, dermatological and systemic level. CONCLUSIONS: It is necessary to continue the documentation of the clinical manifestations of Zika virus, which will be achieved by strengthening epidemiological surveillance.

Introducción: el virus Zika se ha introducido al país y amenaza en propagarse, por lo que el personal de salud se enfrentará a la necesidad de identificar la enfermedad dada una definición operacional de caso; en esta revisión se describen las manifestaciones clínicas de casos probables de Zika de los últimos cinco años. Métodos: se realizó una búsqueda en Google Académico y PubMed con la palabra "Zika". Se conformó una base de datos, se obtuvieron frecuencias simples y se calcularon los límites para proporciones con un alfa del 0.05 por medio de prueba de Wilson. Resultados: se conjuntaron 109 casos probables de fiebre por Zika, las manifestaciones clínicas fueron heterogéneas, con predominio de afectación a nivel musculoesquelético, dermatológico y sistémico. Conclusiones: es necesario continuar la documentación de las manifestaciones clínicas del virus Zika, que se logrará mediante el fortalecimiento de la vigilancia epidemiológica.

[Epidemiological surveillance of febrile rash illness]. / Vigilancia epidemiológica de la enfermedad febril exantemática por casos importados de sarampión.

BACKGROUND: Three imported cases of measles were detected in 2011, so the issue of surveillance with epidemiological alerts intensified. The aim of this article is to describe the phenomenon of intensified surveillance of febrile rash illness before the import of confirmed measles in the country at the Mexican Institute of Social Security cases. METHODS: The cases of epidemiological surveillance system 2011 were obtained was compared with the prior year It was determined t-Student mean difference and Wilson test for proportions, both with an alpha value of 0.05. RESULTS: 2786 cases of febrile rash illness were reported, 51.2 % more cases than the previous year were reported in 2011, the number of reported cases in relation to the expected increase in 29 of the 35 Delegations, an increase in the average number of cases reported from week 26. 67.4 % of reported cases are concentrated in children under 5 years of age. The average days to collect laboratory sample improved after issuing alerts from 3.4 to 2.6 days (p < 0.000000559). CONCLUSIONS: A significant increase in reported cases of febrile rash illness compared with the prior year was appreciated. The Institute has a surveillance system for robust and febrile rash illness, which has identified risks to the population.

Introducción: en 2011 se detectaron tres casos importados de sarampión, por lo que se intensificó la vigilancia epidemiológica con emisión de alertas epidemiológicas. El objetivo de este estudio es describir el fenómeno de la intensificación de la vigilancia epidemiológica de enfermedad febril exantemática ante la importación de casos confirmados de sarampión en el territorio nacional en el Instituto Mexicano del Seguro Social. Métodos: se obtuvieron los casos del sistema especial de vigilancia epidemiológica de 2011, se compararon con el año previo. Se determinó t de Student para diferencia de medias, prueba de Wilson para proporciones; ambas con un valor alfa del 0.05. Resultados: en 2011 se notificaron 2786 casos de enfermedad febril exantemática, 51.2 % más casos que el año anterior; el número de casos reportados con relación a los esperados aumentó en 29 de las 35 Delegaciones del IMSS con un incremento en el promedio de casos notificados a partir de la semana 26. El 67.4 % de los casos notificados se concentró en los menores de 5 años de edad. Conclusiones: se apreció un incremento importante de casos notificados de enfermedad febril exantemática en comparación con el año previo. El Instituto cuenta con un sistema de vigilancia epidemiológica de enfermedad febril exantemática robusto y flexible, que ha permitido identificar riesgos a la población.

[Pertussis in Mexico, an epidemiological overview. A study of 19 years at the Instituto Mexicano del Seguro Social]. / Panorama epidemiológico de la tos ferina. 19 años de estudio epidemiológico en el Instituto Mexicano del Seguro Social.

BACKGROUND: Bordetella pertussis infection remains a public health problem in several developed and developing we describe the epidemiological syndrome cases subsystem special surveillance of whooping cough from 1992 to 2011 at a population with social security. METHODS: We obtained special cases subsystem Pertussis surveillance of 1992-2011. Univariate analysis was made of rates, ratios and proportions. Wilson was determined test for proportions to an alpha of 0.05, t-test for mean difference. RESULTS: We appreciate epidemic cycles every three to five years, the average baseline incidence, excluding epidemic years, 0.1 is considered confirmed cases per 100 000 beneficiaries assigned to family medicine, the highest incidence was recorded in 1997 and 2009. The most affected were children under 1 year of age and in outbreaks, the disease occurred at older ages. CONCLUSIONS: During the period observed intermediate epidemic cycles 5 and 3 years of age presentation is consistent in other countries.

Introducción: La infección por Bordetella pertussis ha sido un problema de salud pública en varios países desarrollados y en vías de desarrollo. El objetivo de este estudio fue describir el panorama epidemiológico de los casos de síndrome coqueluchoide y tos ferina del subsistema especial de vigilancia epidemiológica de 1992 a 2011en una población con seguridad social. Métodos: Se obtuvieron los casos del subsistema especial de vigilancia epidemiológica de tos ferina de 1992 a 2011. Se hizo análisis univariado de tasas, razones y proporciones. Se determinó prueba de Wilson para proporciones a un valor alfa del 0.05, t de Student para diferencia de medias. Resultados: Se aprecian ciclos epidémicos, cada tres a cinco años, la incidencia basal promedio, sin contar los años epidémicos, se considera de 0.1 casos confirmados por cada 100 000 derechohabientes adscritos a medicina familiar, la mayor incidencia se registró en 1997 y 2009. Los más afectados han sido los menores de 1 año de edad y en brotes, la enfermedad se presentó en edades mayores. Conclusión: Durante el periodo se observan ciclos epidémicos intermedios de 5 y 3 años, la presentación de la edad es consistente en otros países.

[Experience on the management of a hepatitis A outbreak in a children daycare center]. / Experiencia en la atención de un brote de hepatitis A en una guardería infantil.

BACKGROUND: Since hepatitis A virus is transmitted via the fecal-oral route, outbreaks in nurseries are favored by constant diaper changes and failures in hygienic measures. The purpose of this investigation was to describe an outbreak of hepatitis A between November 2012 and February 2013 at a nursery in Mexicali, Baja California, as well as the measures adopted for its control. METHODS: A descriptive study was conducted on the outbreak and the control measures, calculating the rates of attack and establishing proportions using the Wilson's scale. Pupils, workers or family members with symptoms consistent with hepatitis A were considered to be suspected cases. First-occurrence hepatitis A records were reviewed on the Weekly Disease Surveillance Report at the involved medical units and on the nursery's infirmary records. RESULTS: The global attack rate was 13.1 %, and in those captive in the nursery, 9.5 %. Jaundice, biliuria and abdominal pain were the most important clinical data. There were no deaths or hospitalizations. The outbreak lasted 86 days. Control measures were based on epidemiological surveillance reinforcement and preventive hygienic measures. CONCLUSIONS: The outbreak showed a spreading trend, it affected mainly children and showed the importance of health education and epidemiological surveillance maintenance, extensive to the familial setting.

INTRODUCCIÓN: dado que el virus de la hepatitis A se transmite vía fecal-oral, en las guarderías los brotes son favorecidos por los cambios constantes de pañal y las fallas en las medidas higiénicas. El objetivo de esta investigación fue describir un brote de hepatitis A entre noviembre de 2012 y febrero de 2013 en una guardería de Mexicali, Baja California, así como las medidas adoptadas para su control. MÉTODOS: se realizó un estudio descriptivo del brote y de las medidas de control, con cálculo de tasas de ataque y determinación de proporciones por escala de Wilson. Se consideró caso sospechoso a los alumnos, trabajadores o familiares que presentaran sintomatología compatible con hepatitis A. Se revisaron los registros de primera vez de hepatitis A del Informe Semanal de Casos Nuevos de Enfermedades de las unidades médicas involucradas y de los registros de enfermería de la guardería. RESULTADOS: la tasa de ataque global fue de 13.1 % y en los cautivos de la guardería, de 9.5 %. La ictericia, la coluria y el dolor abdominal fueron los principales datos clínicos. No se presentaron defunciones ni hospitalizaciones. El brote duró 86 días. Las medidas de control se basaron en el reforzamiento de la vigilancia epidemiológica y de las medidas higiénicas preventivas. CONCLUSIONES: el brote mostró una tendencia a la propagación, afectó principalmente a los niños y denotó la importancia de la educación en salud y del mantenimiento de la vigilancia epidemiológica, con extensión al medio familiar.