Introduction of measles into a highly immunised West African community: the role of health care institutions

Synthesis of Evidence to Characterize National Measles and Rubella Exposure and Immunization Histories

Population immunity depends on the dynamic levels of immunization coverage that countries achieve over time and any transmission of viruses that occur within the population that induce immunity. In the context of developing a dynamic transmission model for measles and rubella to support analyses of future immunization policy options, we assessed the model inputs required to reproduce past behavior and to provide some confidence about model performance at the national level. We reviewed the data available from the World Health Organization (WHO) and existing measles and rubella literature for evidence of historical reported routine and supplemental immunization activities and reported cases and outbreaks. We constructed model input profiles for 180 WHO member states and three other areas to support disease transmission model development and calibration. The profiles demonstrate the significant variability in immunization strategies used historically by regions and member states and the epidemiological implications of these historical choices. The profiles provide a historical perspective on measles and rubella immunization globally at the national level, and they may help immunization program managers identify existing immunity and/or knowledge gaps.

Strategies for minimizing nosocomial measles transmission

As a result of the highly contagious nature of measles before the onset of rash, nosocomial transmission will remain a threat until the disease is eradicated. However, a number of strategies can minimize its nosocomial spread. It is therefore vital to maximize awareness among health care staff that an individual with measles can enter a health facility at any time and that a continual risk of the nosocomial transmission of measles exists. The present review makes two groups of recommendations: those which are generally applicable to all countries, and certain additional recommendations which may be suitable only for industrialized countries.

Immunization in urban areas: issues and strategies

In the past, immunization programmes have focused primarily on rural areas. However, with the recognition of the increasing numbers of urban poor, it is timely to review urban immunization activities. This update addresses two questions: Is there any need to be concerned about urban immunization and, if so, is more of the same kind of rural EPI activity needed or are there specific urban issues that need specific urban strategies? Vaccine-preventable diseases have specific urban patterns that require efficacious vaccines for younger children, higher target coverage levels, and particular focus to ensure national and global eradication of poliomyelitis. Although aggregate coverage levels are higher in urban than rural areas, gaps are masked since capital cities are better covered than other urban areas and the coverage in the poorest slum and periurban areas within cities is as bad as or worse than that in rural areas. Difficult access to immunization services in terms of distance, costs, and time can still be the main barrier in some parts of the city. Mobilization and motivation strategies in urban areas should make use of the mass media and workplace networks as well as the traditional word-of-mouth strategies. Use of community health workers has been successful in some urban settings. Management issues concern integration of the needs of the poor into a coherent city health plan, coordination of different health providers, and clear lines of responsibility for addressing the needs of new, urbanizing areas.

Gender and the pattern of transmission of measles infection. A reanalysis of data from the Machakos area, Kenya

Data on measles from the project in the Machakos district, Kenya between 1974 and 1981 have been reanalysed in order to test the impact of sex and cross-sex transmission on severity of infection. In families with several cases, the case fatality rate was high as 11.3% (13/115) during the initial 6 months of the project. In the remaining period, the case fatality rate fell to 2.4% (21/885) (relative risk (RR) = 0.21, 95% confidence interval (CI): 0.11-0.39). During the initial period with high mortality, second cases had 4.74 times higher mortality (95% CI: 1.65-13.66) than index cases and there was no difference in mortality between girls and boys (RR = 0.98). Among secondary cases, though not significant, those infected by someone of the opposite sex had a trend toward a higher risk of dying than those infected by someone of their own sex (RR = 2.44, 95% CI: 0.77-7.78). In families with two children of the same sex, the case fatality rate was 9% compared with 29% in families with a boy and a girl (RR = 3.49; 95% CI: 0.96-12.75). In the subsequent period with low mortality, the difference in mortality between index and secondary cases was less pronounced (RR = 2.32, 95% CI: 1.03-5.25) and girls had significantly higher case fatality than boys (RR = 2.63, 95% CI: 1.09-6.34). There was no difference in this case fatality rate associated with cross-sex transmission of infection (RR = 0.88).(ABSTRACT TRUNCATED AT 250 WORDS)

Measles epidemic in Harare, Zimbabwe, despite high measles immunization coverage rates

Despite rapidly increasing measles immunization coverage in Harare city, measles remains endemic, and regular outbreaks occur. The most recent occurred in 1988, when the measles immunization coverage was 83%. We have carried out a retrospective study of the clinical and epidemiological features of this outbreak to assess whether the present immunization policy needs to be changed. Of 4357 cases of measles seen at primary health care centres and hospitals in Harare during the outbreak, 1399 (32%) were severe or involved complications that required hospital admission. The peak incidence occurred among under-2-year-olds, followed by that among 5-7-year-olds. Poor nutritional status was significantly more frequent among children who were hospitalized and among those who died. A total of 59% of all cases aged 9-59 months had documented evidence of measles immunization. The most frequent complications, which occurred most often among under-5-year-olds, were diarrhoea with dehydration, pneumonia, laryngotracheobronchitis, and convulsions, which together affected 56% of hospitalized cases. The hospital case fatality rate was low (1.43%). In Harare, measles transmission remains a problem, despite high measles immunization coverage rates; the failure rate for the standard Schwarz measles vaccine also appears to be high. There is a need to reduce the number of measles cases among under-9-month-olds and young children. Further studies into alternative measles vaccines and schedules are required.

Medical technologies in developing countries: issues of technology development, transfer, diffusion and use

The difficulties experienced in transfer of medical technology to developing countries are aggravated by partial and incomplete understanding of the cultural, social, economic, and institutional factors affecting technology development, transfer, dissemination and use. In this paper, it is argued that a more dynamic and comprehensive approach is needed for the analysis of these factors. Such an approach would provide the basis for linking existing information stemming from partial analyses of problems related to individual users, the health services or systems, and the technology itself. The starting point of any comprehensive analysis must be the structure of the society in which the technology is to be used. The value of a comprehensive analytical approach is illustrated by discussion of a medical technology still under development, a vaccine against malaria. This discussion further indicates that consideration of cultural, social, economic, and institutional factors in the developmental phases of a technology can contribute to ensuring acceptability and sustainability of the technology under the multifaceted conditions in which it is to be used.

High measles mortality in infancy related to intensity of exposure

In a West African urban community, measles infection in infants was examined over 5 years (1979-1983). In the age group 0 to 11 months, measles mortality was higher among secondary cases (infected in the house) than among index cases (infected outside the house), and the proportion of secondary cases was significantly higher for this age group than for older children. Intensive exposure related to the social pattern of disease transmission may be important in explaining the high infant mortality observed with measles in developing countries. Mortality during the first 12 months of life increased with age, presumably because of the decrease of maternally derived measles antibodies. In children younger than 6 months of age, who are usually considered to be protected by maternal antibody, intensive exposure may lead to infection, as demonstrated by a high level of measles-specific antibodies in some children exposed to an older sibling with measles. The aim of public health policies should be to change conditions of exposure.