International journal of epidemiology
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Comparative Study
Application of Markov process modelling to health status switching behaviour of infants.
This study is an attempt to apply Markov process modelling to health status switching behaviour of infants. The data for the study consist of monthly records of diagnosed illnesses for 1152 children, each observed from the month of first contact with Kasangati Health Centre, Kampala, Uganda, until age 18 months. ⋯ The study has shown that the transitions between Health and Illness for infants, from month to month, can be modelled by a Markov Chain for which the (single-step) transition probabilities are generally time-dependent or age-dependent. After the first few months of life the dependence on age may wear off, as in this study, leading to a time-homogeneous Markov Chain, which eventually attains a steady state distribution in about 12 months. Interpretations of the transition probabilities as measures of disease prevalence are discussed.
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In general females have a lower mortality than males at all ages. Excess female mortality has been documented in certain high mortality situations, in particular in South Asia. However, females may have a higher mortality for certain causes of death. One of the causes of death for which excess female mortality is suspected is measles. ⋯ When pooled together, the results show an excess of female mortality from birth until age 50 years. The excess female mortality appears small at age 0-4 (+4.2%), larger at age 5-14 (+10.9%) and peaks during the female reproductive period, at age 15-44 (+42.6%). This pattern of excess female mortality occurs in all the major regions of the world: Europe, North and South America, Far-East Asia, the Middle East and South Asia. The only noticeable exceptions are the Philippines and Thailand. The validity of the finding is extensively reviewed. Emphasis lies on the statistical power to prove that sex differences in measles mortality do exist, on the critical analysis of a case study in England and Wales, on the comparison with the overall pattern of sex differences and on available data on sex differences in incidence. Possible explanations are reviewed.
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To improve measles control in Kinshasa, Zaire, a project to increase vaccine coverage was begun in 1988, and in 1989, the city vaccination programme changed measles vaccination policy from Schwartz vaccine at age 9 months to medium titre Edmonston Zagreb (EZ) vaccine at age 6 months. We report the impact of the programme on measles incidence and mortality. ⋯ Measles can be controlled in urban areas, although it is difficult to determine how great a contribution vaccination at age 6 months makes over and above the achievement of high coverage.
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Infections may be involved in some cases of sudden infant death syndrome (SIDS). Exposure to such infections is likely to differ considerably between areas depending on rates of population mixing. It is therefore possible that the geography of SIDS will reflect that of population migration. ⋯ It is concluded that geographical variations in SIDS deaths in England and Wales are strongly associated with differences in rates of population mixing as measured by migration. The findings support the hypothesis that population mixing, by its influence on exposure to infections, may be a significant factor in the aetiology of SIDS.
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Infant feeding is a multidimensional activity that can be described and analysed in many different ways. The World Health Organization (WHO) has recently issued recommended indicators for assessing infant feeding practices. This paper presents these indicators and demonstrates their applications using the 1989 Demographic and Health Survey (DHS) data for Bolivia. ⋯ Mothers who have moved to the city since the age of 12 are most likely to be giving their infants other milks in addition to breast milk and to be bottle feeding their infants. The WHO infant feeding indicators provide a useful framework for quantifying infant feeding practices, and most of the indicators can readily be applied to DHS data. Nonetheless, improvements can be made in both the indicators themselves and the DHS questionnaire to improve reporting of internationally comparable infant feeding information.