Weather-based prediction of Plasmodium falciparum malaria in epidemic-prone regions of Ethiopia II. Weather-based prediction systems perform comparably to early detection systems in identifying times for interventions

BACKGROUND: Timely and accurate information about the onset of malaria epidemics is essential for effective control activities in epidemic-prone regions. Early warning methods that provide earlier alerts (usually by the use of weather variables) may permit control measures to interrupt transmission earlier in the epidemic, perhaps at the expense of some level of accuracy. METHODS: Expected case numbers were modeled using a Poisson regression with lagged weather factors in a 4(th)-degree polynomial distributed lag model. For each week, the numbers of malaria cases were predicted using coefficients obtained using all years except that for which the prediction was being made. The effectiveness of alerts generated by the prediction system was compared against that of alerts based on observed cases. The usefulness of the prediction system was evaluated in cold and hot districts. RESULTS: The system predicts the overall pattern of cases well, yet underestimates the height of the largest peaks. Relative to alerts triggered by observed cases, the alerts triggered by the predicted number of cases performed slightly worse, within 5% of the detection system. The prediction-based alerts were able to prevent 10–25% more cases at a given sensitivity in cold districts than in hot ones. CONCLUSIONS: The prediction of malaria cases using lagged weather performed well in identifying periods of increased malaria cases. Weather-derived predictions identified epidemics with reasonable accuracy and better timeliness than early detection systems; therefore, the prediction of malarial epidemics using weather is a plausible alternative to early detection systems

Scaling Up Malaria Control in Africa: An Economic and Epidemiological Assessment

This paper estimates the number of people at risk of contracting malaria in Africa using GIS methods and the disease's epidemiologic characteristics. It then estimates yearly costs of covering the population at risk with the package of interventions (differing by level of malaria endemicity and differing for rural and urban populations) for malaria as recommended by the UN Millennium Project. These projected costs are calculated assuming a ramp-up of coverage to full coverage by 2008, and then projected out through 2015 to give a year-by-year cost of meeting the Millennium Development Goal for reducing the burden of malaria by 75% We conclude that the cost of comprehensive malaria control for Africa is US$3.0 billion per year on average, or around US$4.02 per African at risk.

Alert Threshold Algorithms and Malaria Epidemic Detection

We describe a method for comparing the ability of different alert threshold algorithms to detect malaria epidemics and use it with a dataset consisting of weekly malaria cases collected from health facilities in 10 districts of Ethiopia from 1990 to 2000. Four types of alert threshold algorithms are compared: weekly percentile, weekly mean with standard deviation (simple, moving average, and log-transformed case numbers), slide positivity proportion, and slope of weekly cases on log scale. To compare dissimilar alert types on a single scale, a curve was plotted for each type of alert, which showed potentially prevented cases versus number of alerts triggered over 10 years. Simple weekly percentile cutoffs appear to be as good as more complex algorithms for detecting malaria epidemics in Ethiopia. The comparative method developed here may be useful for testing other proposed alert thresholds and for application in other populations

Weather-based prediction of Plasmodium falciparum malaria in epidemic-prone regions of Ethiopia I. Patterns of lagged weather effects reflect biological mechanisms

BACKGROUND: Malaria epidemics due to Plasmodium falciparum are reported frequently in the East African highlands with high case fatality rates. There have been formal attempts to predict epidemics by the use of climatic variables that are predictors of transmission potential. However, little consensus has emerged about the relative importance and predictive value of different factors. Understanding the reasons for variation is crucial to determining specific and important indicators for epidemic prediction. The impact of temperature on the duration of a mosquito's life cycle and the sporogonic phase of the parasite could explain the inconsistent findings. METHODS: Daily average number of cases was modeled using a robust Poisson regression with rainfall, minimum temperature and maximum temperatures as explanatory variables in a polynomial distributed lag model in 10 districts of Ethiopia. To improve reliability and generalizability within similar climatic conditions, we grouped the districts into two climatic zones, hot and cold. RESULTS: In cold districts, rainfall was associated with a delayed increase in malaria cases, while the association in the hot districts occurred at relatively shorter lags. In cold districts, minimum temperature was associated with malaria cases with a delayed effect. In hot districts, the effect of minimum temperature was non-significant at most lags, and much of its contribution was relatively immediate. CONCLUSIONS: The interaction between climatic factors and their biological influence on mosquito and parasite life cycle is a key factor in the association between weather and malaria. These factors should be considered in the development of malaria early warning system

Physical condition of Olyset® nets after five years of utilization in rural western Kenya

Background: Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria control at present, and millions are used each day across the globe. However, there is limited information about the durability of LLINs under different conditions of utilization and there is no consensus about when a LLIN ceases to be protective due to physical deterioration. This knowledge is important for malaria control programmes to plan for procurement and replacement. Methods: A cross-sectional survey of 208 households where Olyset® nets distributed five years ago were still present was conducted in the village of Sauri, western Kenya, in the context of the Millennium Villages Project. Information on bed net utilization and maintenance was collected in each household through a structured questionnaire, and one five-year-old Olyset® net from each sampled household was randomly selected and collected for physical examination. All holes larger than 0.5 cm were measured in each net, registering their position, and a hole index was calculated following WHO guidelines. Nets were classified as in good condition, moderately damaged or badly torn based on the hole index. The analysis explored the associations between demographic and socioeconomic characteristics of households, patterns of bed net utilization and maintenance and physical condition of the nets. Additional analysis was conducted using malaria prevalence data collected in a separate survey to explore if there was any association between the condition of the net collected in a household and the presence of malaria parasites in members of that household. Results: 81.4% of Olyset® nets distributed five years ago were still present in the surveyed households, and 98.97% of the nets were reportedly used the previous night. Nets had an average of 34.2 holes (95% CI 30.12-38.22), and the mean hole index was 849 (95% CI 711–986), IQR 174–1,135. 15.2% of nets were still in good condition, 46.1% were moderately damaged and 38.7% were badly torn after five years of utilization. There was no association between household characteristics or patterns of bed net utilization or maintenance and physical condition of the nets. The only predictor of the physical condition of the net was the cleanliness at the time of examination. There was a difference of 17.6 percentage points in the proportion of households with at least one blood smear positive for Plasmodium falciparum between households with a net in good condition (5.3%) and those with a moderately damaged or badly torn net (22.9%), 95% CI (0.04-0.305), t=2.77 with unequal variance, p=0.009. Conclusions: Olyset® nets were used extensively in Sauri, western Kenya after five years of distribution, regardless of their physical condition. However, only 15% were found in good condition. Nets in good condition seem to be still protective after five years of utilization, while nets with more than 100 cm2 of holed surface may be associated with higher malaria parasitaemia at household level. Continued replacement of damaged nets and promotion of net maintenance and repair may be necessary to maintain the protective effectiveness of LLINs

Community-based malaria control programme in Tigray Region, Northern Ethiopia: Results of a mortality survey of rural under-five children

Abstract: A mortality survey of children under five years of age was undertaken in Tigray Region, in rural areas covered by a community-based malaria control programme. A multistage cluster sampling technique was used to define the sample. Trained Malaria Control Programme personnel conducted interviews in 4660 households. Total under-five population sampled was 7335, in which 190 deaths were reported in one year. Median duration of illness before death was 14 days, mean age at death 1.5 years, and 53% of those who died were male. Forty five percent died without being taken to a Community Health Worker (CHW) or to a health facility before death, and 92% of the deaths occurred at home. Overall, 12% of deaths were reported by families due to fever or malaria. Death rate (age 0-4) was 25.9%. Estimated age specific mortality rate (age 0-4) was 26.3%, underfive mortality rate (U5MR) was 163%, and malaria-specific mortality rate based on lay reporting was 3.3%. Two districts were found to have very high mortality with estimated U5MRs of 372% and 290%. Based on these findings, increased efforts are being made in the Community-Based Malaria Control Programme to educate families about the importance of early diagnosis and treatment and the use of CHW services for ill children. Areas for investigating the determinants of the marked district mortality differentials are discussed. [Ethiop. J. Health Dev. 1998;12(3):203-211

Forecasting malaria incidence from historical morbidity patterns in epidemic-prone areas of Ethiopia: a simple seasonal adjustment method performs best.

The aim of this study was to assess the accuracy of different methods of forecasting malaria incidence from historical morbidity patterns in areas with unstable transmission. We tested five methods using incidence data reported from health facilities in 20 areas in central and north-western Ethiopia. The accuracy of each method was determined by calculating errors resulting from the difference between observed incidence and corresponding forecasts obtained for prediction intervals of up to 12 months. Simple seasonal adjustment methods outperformed a statistically more advanced autoregressive integrated moving average method. In particular, a seasonal adjustment method that uses mean deviation of the last three observations from expected seasonal values consistently produced the best forecasts. Using 3 years' observation to generate forecasts with this method gave lower errors than shorter or longer periods. Incidence during the rainy months of June-August was the most predictable with this method. Forecasts for the normally dry months, particularly December-February, were less accurate. The study shows the limitations of forecasting incidence from historical morbidity patterns alone, and indicates the need for improved epidemic early warning by incorporating external predictors such as meteorological factors

Rapid urban malaria appraisal (RUMA) in sub-Saharan Africa

BACKGROUND: The rapid urban malaria appraisal (RUMA) methodology aims to provide a cost-effective tool to conduct rapid assessments of the malaria situation in urban sub-Saharan Africa and to improve the understanding of urban malaria epidemiology. METHODS: This work was done in Yopougon municipality (Abidjan), Cotonou, Dar es Salaam and Ouagadougou. The study design consists of six components: 1) a literature review, 2) the collection of available health statistics, 3) a risk mapping, 4) school parasitaemia surveys, 5) health facility-based surveys and 6) a brief description of the health care system. These formed the basis of a multi-country evaluation of RUMA's feasibility, consistency and usefulness. RESULTS: A substantial amount of literature (including unpublished theses and statistics) was found at each site, providing a good overview of the malaria situation. School and health facility-based surveys provided an overview of local endemicity and the overall malaria burden in different city areas. This helped to identify important problems for in-depth assessment, especially the extent to which malaria is over-diagnosed in health facilities. Mapping health facilities and breeding sites allowed the visualization of the complex interplay between population characteristics, health services and malaria risk. However, the latter task was very time-consuming and required special expertise. RUMA is inexpensive, costing around 8,500–13,000 USD for a six to ten-week period. CONCLUSION: RUMA was successfully implemented in four urban areas with different endemicity and proved to be a cost-effective first approach to study the features of urban malaria and provide an evidence basis for planning control measures

The African Millennium Villages

We describe the concept, strategy and initial results of the Millennium Villages Project (MVP) and implications regarding sustainability and scalability. Our underlying hypothesis is that the interacting crises of agriculture, health, and infrastructure in rural Africa can be overcome through targeted public-sector investments to raise rural productivity, and thereby to increased private-sector saving and investments. This is carried out by empowering impoverished communities with science-based interventions. 78 Millennium Villages have been initiated in 12 sites in 10 African countries, each representing a major agroecological zone In early results, the research villages in Kenya, Ethiopia and Malawi have reduced malaria prevalence, met caloric requirements, generated crop surpluses, enabled school feeding programs, and provided cash earnings for farm families

The effect of an integrated multisector model for achieving the Millennium Development Goals and improving child survival in rural sub-Saharan Africa: a non-randomised controlled assessment

Background Simultaneously addressing multiple Millennium Development Goals (MDGs) has the potential to complement essential health interventions to accelerate gains in child survival. The Millennium Villages project is an integrated multisector approach to rural development operating across diverse sub-Saharan African sites. Our aim was to assess the effects of the project on MDG-related outcomes including child mortality 3 years after implementation and compare these changes to local and national reference data