Case-Control Study of Risk Factors for Meningococcal Disease in Chile.

An outbreak of meningococcal disease with a case-fatality rate of 30% and caused by predominantly serogroup W of Neisseria meningitidis began in Chile in 2012. This outbreak required a case-control study to assess determinants and risk factors for infection. We identified confirmed cases during January 2012-March 2013 and selected controls by random sampling of the population, matched for age and sex, resulting in 135 case-patients and 618 controls. Sociodemographic variables, habits, and previous illnesses were studied. Analyses yielded adjusted odds ratios as estimators of the probability of disease development. Results indicated that conditions of social vulnerability, such as low income and overcrowding, as well as familial history of this disease and clinical histories, especially chronic diseases and hospitalization for respiratory conditions, increased the probability of illness. Findings should contribute to direction of intersectoral public policies toward a highly vulnerable social group to enable them to improve their living conditions and health.

[Clinical features and prognostic factors of meningococcal disease: a case series study in Chile during the 2012-2013 outbreak]. / Características clínicas y factores pronósticos de la enfermedad meningocóccica: un estudio de serie de casos en Chile durante el brote 2012-2013.

INTRODUCTION: Meningococcal disease (MD) is a major global problem because of its case fatality rate and sequels. Since 2012 cases of serogroup W have increased in Chile, with nonspecific clinical presentation, high case fatality rate and serious consequences. OBJECTIVE: To characterize the evolution and outcome of MD cases between January 2012 and March 2013 in Chile. MATERIAL AND METHODS: Case series considering 149 MD cases of 7 regions. A questionnaire was applied and clinical records were reviewed, including individual, agent, clinical course and healthcare process variables. The analysis allowed to obtain estimates of the OR as likelihood of dying. RESULTS: 51.5% was meningococcemia, the case fatality rate reached 27%, prevailing serogroup W (46.6%). Factors that increased the probability of dying: > age, belonging to indigenous people, having lived a stressful event, having diarrhea, impaired consciousness, cardiovascular symptoms, low oxygen saturation and low Glasgow coma scale score. DISCUSSION: The case fatality rate exceeded normal levels and was higher in serogroup W. Increasing in this serogroup, associated to the increased presence of nonspecific symptoms or rapid progression to septicemia, hit a health system accustomed to more classic meningococcal disease presentation, which could partly explain the observed increased fatality rate.

Características clínicas y factores pronósticos de la enfermedad meningocóccica: un estudio de serie de casos en Chile durante el brote 2012-2013 / Clinical features and prognostic factors of meningococcal disease: a case series study in Chile during the 2012-2013 outbreak

Introduction: Meningococcal disease (MD) is a major global problem because of its case fatality rate and sequels. Since 2012 cases of serogroup W have increased in Chile, with nonspecific clinical presentation, high case fatality rate and serious consequences. Objective: To characterize the evolution and outcome of MD cases between January 2012 and March 2013 in Chile. Material and Methods: Case series considering149 MD cases of 7 regions. A questionnaire was applied and clinical records were reviewed, including individual, agent, clinical course and healthcare process variables. The analysis allowed to obtain estimates of the OR as likelihoodof dying. Results: 51.5% was meningococcemia, the case fatality rate reached 27%, prevailing serogroup W (46.6%). Factors that increased the probability of dying: > age, belonging to indigenous people, having lived a stressful event, having diarrhea, impaired consciousness, cardiovascular symptoms, low oxygen saturation and low Glasgow coma scale score. Discussion: The case fatality rate exceeded normal levels and was higher in serogroup W. Increasing in this serogroup, associated to the increased presence of nonspecific symptoms or rapid progression to septicemia, hit a health system accustomed to more classic meningococcal disease presentation, which could partly explain the observed increased fatality rate.

Introducción: La enfermedad meningocóccica (EM) es un importante problema mundial por su letalidad y secuelas. Desde 2012 aumentaron en Chile los casos por serogrupo W, con presentación clínica inespecífica, elevada letalidad y secuelas graves. Objetivo: Caracterizar la evolución y desenlace de EM en casos desde enero de 2012 a marzo de 2013 en Chile. Material y Método: Serie de 149 casos de EM de siete regiones. Se aplicó un cuestionario y se revisaron registros clínicos, incluyendo variables del individuo, agente, curso clínico y proceso de atención. Los análisis permitieron obtener OR como estimadores de la probabilidad de fallecer. Resultados: El 51,5% se presentó como meningococcemia, la letalidad alcanzó a 27%, predominando el serogrupo W (46,6%). Aumentaron la probabilidad de fallecer: una mayor edad, pertenencia a pueblos originarios, haber vivido evento estresante, presentar diarrea, compromiso de conciencia, síntomas cardiovasculares, baja saturación de oxígeno y bajo puntaje de Glasgow. Discusión: La letalidad superó las frecuencias habituales y fue mayor en el serogrupo W. El aumento de este serogrupo, asociado a la mayor presencia de síntomas inespecíficos o a la rápida progresión a septicemia, impactó en un sistema de salud habituado a cuadros más clásicos de EM, lo que podría explicar en parte, la mayor letalidad observada.