Background: Varicella (chickenpox) is the primary disease caused by varicella-zoster virus. It is extremely contagious and is frequent in children. Indeed, in the absence of vaccination, a high proportion of the population is liable to contract it. Herpes zoster -more frequent among adultsis caused by reactivation of the latent virus. The objective of this study is to describe the status of and time trend for varicella and herpes zoster in the Madrid Autonomous Region prior to the introduction of the vaccine to the general population.

This study was designed to analyze the relationship between breast-feeding and mental development at 24 months of age, independently of the influence of other factors. A total of 238 babies born between October 1995 and February 1998 were enrolled in an observational prospective cohort study. Cognitive development was assessed using the Bayley Infant Development Scale. The results of multiple linear regression analysis showed that infants breast-fed for longer than 4 months scored 4.3 points higher on the mental development scale than those breast-fed for less time. No differences were found in psychomotor development as a function of feeding regimen or duration. The positive linear correlation observed between parental IQ and mental development scores at 24 months was also statistically significant (mother: r = 0.39; p < 0.001; father: r = 0.43; p < 0.001). It may be concluded that breast-feeding for longer than 4 months has a positive effect on the child's mental development at 24 months of age. Parental intelligence also appears to influence cognitive development.

The purpose of this study was to analyze the effects of breast-feeding on cognitive and motor development. A prospective cohort study was carried out enrolling 249 babies from 2 rural and urban areas. Cognitive development was assessed at the age of 18 months. Results show that adjusted scores on the mental development index were 4.6 points higher in babies breast-fed for longer than 4 months than in those breast-fed for less time. No differences in psychomotor development were found as a function of type of feeding. A statistically-significant linear correlation was observed between the duration of breast-feeding and scores for Bayley's mental development index. These data suggest that breast-feeding for longer than 4 months has a positive effect on the baby's mental development measured at 18 months of age. Parental intelligence quotient also seems to have an influence on cognitive development.

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