Seroepidemiología de la hepatitis A en México: sensor de inequidad social e indicador de políticas de vacunación / Seroepidemiology of hepatitis A in Mexico: a detector of social inequity and monitor of immunization policies

RESUMEN

OBJETIVO: Estudiar la distribución y frecuencia de los anticuerpos contra el virus de la hepatitis A en una muestra probabilística en México con representatividad estatal, así como analizar los factores de riesgo y los patrones epidemiológicos. MATERIAL Y MÉTODOS: A partir de la Encuesta Nacional de Salud se estudiaron 4 907 sueros seleccionados de forma aleatoria para anticuerpos contra VHA mediante ensayo inmunoenzimático. Los sueros se recolectaron de noviembre de 1999 a junio del 2000 a nivel nacional. RESULTADOS: Se encontró seroprevalencia general de 81.3 por ciento (IC 78.6-84.2), y los resultados expandidos permiten inferir que existen 78.7 millones de mexicanos infectados. Los factores de riesgo en menores de nueve años incluyen residir en entidades sureñas (RM= 5.3), localidades rurales (RM= 3.1), provenir de familia con bajos ingresos (RM= 2.4) y habitar viviendas con acceso limitado a servicios sanitarios (agua, RM= 2.5; drenaje, RM= 2.7). CONCLUSIONES: Los patrones de transmisión heterogéneos y las diferencias en las pre-valencias de infección indican inequidad en las poblaciones estudiadas, explicables por diferencias en las condiciones sanitarias y sociales. Se discuten las ventajas de intervenciones poblacionales tales como la vacunación y el fortalecimiento de las condiciones sanitarias y socioeconómicas.

ABSTRACT

OBJECTIVE: Hepatitis A Virus (HAV) in Mexico has traditionally been considered a disease with a homogeneous pattern of transmission, high rates of infection at early ages, and infrequent complication rates. The purpose of this study was to take advantage of the 2000 NHS, a probabilistic population-based survey, in order to describe the seroepidemiology of HAV infection in Mexico. MATERIAL AND METHODS: This study is based on information obtained from the National Health Survey that was conducted in 2000. The present report is based on 4 907 randomly selected samples that were studied to determine the prevalence of HAV antibodies using immunoenzymatic assay. Sera were collected from November 1999 to June 2000. RESULTS: Seroprevalence among the general population was 81.3 percent (CI95 percent: 78.6-84.2); expanded results allow the inference that 78.7 million Mexicans have been infected by this agent. Risk factors for HAV among children younger than nine years of age are the following: residence in southern states OR=5.3, residence in rural communities OR= 3.1, low-income family OR= 2.4 and living in households with limited access to sanitary facilities (water OR= 2.5 and sewage OR= 2.7). CONCLUSIONS: Results of this study demonstrate that HAV transmission patterns are heterogeneous and that differentials in the prevalence of infection are due to sanitary and social inequity among studied populations. Finally, the advantages of adopting public health measures such as vaccination and improvement of sanitary and socioeconomic conditions are discussed.