The economic impact of HIV/AIDS on the education sector in Zambia.

OBJECTIVES: To estimate and project the economic impact of HIV/AIDS on the supply of education in Zambia. DESIGN: An analysis of the financial implications of HIV/AIDS for the Ministry of Education (MoE) and donors funding education in Zambia. METHODS: A mathematical model was used to project the number of primary school teachers and their HIV status under current plans for teacher training and recruitment. Cost data were compiled from the MoE, the Teacher Education Department, teacher training colleges and the donor consortium BESSIP (Basic Education Sub-Sector Investment Programme). Multivariate sensitivity analyses were performed. RESULTS: The impact of HIV/AIDS on the supply of primary education imply costs to the MoE and BESSIP estimated at US$1.3-3.1 million in 1999, and projected at $10.6-41.3 million over the period 1999-2010. These costs include salaries paid to teachers absent as a result of HIV-associated illness (71%), additional training of teachers to cope with AIDS-related attrition (22%) and funeral costs contractually met by the MoE (7%). They do not include the additional costs of an active care and prevention response by the MoE, or the burden of ensuring enrolment of AIDS orphans. The annual cost of HIV/AIDS is a relatively small fraction of the overall MoE budget (2.5% in 1999) but has substantial implications for resource allocation to some functions. Expenditure on teacher training will need to increase by 26% if Education for All targets are to be met in the face of AIDS. CONCLUSIONS: HIV/AIDS has significant implications for resource allocation in the education sector in Zambia.

Use of remote sensing and a geographical information system in a national helminth control programme in Chad.

OBJECTIVE: To design and implement a rapid and valid epidemiological assessment of helminths among schoolchildren in Chad using ecological zones defined by remote sensing satellite sensor data and to investigate the environmental limits of helminth distribution. METHODS: Remote sensing proxy environmental data were used to define seven ecological zones in Chad. These were combined with population data in a geographical information system (GIS) in order to define a sampling protocol. On this basis, 20 schools were surveyed. Multilevel analysis, by means of generalized estimating equations to account for clustering at the school level, was used to investigate the relationship between infection patterns and key environmental variables. FINDINGS: In a sample of 1023 schoolchildren, 22.5% were infected with Schistosoma haematobium and 32.7% with hookworm. None were infected with Ascaris lumbricoides or Trichuris trichiura. The prevalence of S. haematobium and hookworm showed marked geographical heterogeneity and the observed patterns showed a close association with the defined ecological zones and significant relationships with environmental variables. These results contribute towards defining the thermal limits of geohelminth species. Predictions of infection prevalence were made for each school surveyed with the aid of models previously developed for Cameroon. These models correctly predicted that A. lumbricoides and T. trichiura would not occur in Chad but the predictions for S. haematobium were less reliable at the school level. CONCLUSION: GIS and remote sensing can play an important part in the rapid planning of helminth control programmes where little information on disease burden is available. Remote sensing prediction models can indicate patterns of geohelminth infection but can only identify potential areas of high risk for S. haematobium.

First nationwide survey of the health of schoolchildren in Chad.

Survey data are presented from a nationwide survey of the health of schoolchildren in Chad. The country was stratified into distinct ecological zones based on satellite sensor environmental data. Twenty schools were visited and 1024 children aged between 6 and 15 years were included in the study. The overall prevalence of stunting, underweight, anaemia and goitre was 18.7, 16.5, 25.1 and 23.3%, respectively. Schistosoma haematobium, Schistosoma mansoni and hookworm were the only helminth species found with prevalences of 13.2, 1 and 32.7%, respectively. A greater proportion of boys were stunted, underweight, anaemic and infected with S. haematobium and hookworm than girls. Older children were more stunted, underweight and infected with S. haematobium and hookworm than younger children, but less anaemic. The prevalence of infection showed marked geographical heterogeneity, with hookworm prevalence being highest in the Sudanian and tropical zone, and S. haematobium being most prevalent in the Sahelian zone and the Logone and Chari basins in the west of the country. These data show that there is a high prevalence of helminth infection in Chad, but that treatment for S. haematobium and hookworm should be targeted to different geographical areas.

Tools from ecology: useful for evaluating infection risk models?

Despite the increasing number of models to predict infection risk for a range of diseases, the assessment of their spatial limits, predictive performance and practical application are not widely undertaken. Using the example of Schistosoma haematobium in Africa, this article illustrates how ecozonation and receiver-operator characteristic analysis can help to assess the usefulness of available models objectively.