Case Report: Primaquine Failure for Radical Cure of Plasmodium vivax Malaria in Gambella, Ethiopia

Failures of primaquine for the treatment of relapsed Plasmodium vivax malaria is a serious challenge to malaria elimination in Ethiopia, where P. vivax accounts for up to 40% of malaria infections. We report here occurrence of a total of 15 episodes of primaquine treatment failure for radical cure in three historical P. vivax malaria patients from Gambella, Ethiopia, during 8-16 months of follow-up in 1985-1987. The total primaquine doses received were 17.5 mg/kg, 25.8 mg/kg, and 35.8 mg/kg, respectively. These total doses are much higher than in previous reports of patients with treatment failure in Ethiopia and East Africa. The possibility of new infection was excluded for these cases as the treatment and follow-up were carried out in Addis Ababa, a malaria-free city. Recrudescences were unlikely, considering the short duration pattern of the recurrences. The cytochrome P450 2D6 (CYP2D6) status for these patients is unknown, but polymorphisms have been described in Ethiopia and may have contributed to primaquine treatment failures. It is suggested that further studies be carried out in Ethiopia to determine the prevalence and distribution of primaquine treatment failures in different ethnic groups, considering the impact of CYP2D6 polymorphisms and the potential value of increasing the primaquine dose to avoid relapse.

Factors influencing the uptake of voluntary HIV counseling and testing in rural Ethiopia: a cross sectional study

Background

Voluntary counseling and testing (VCT) has been one of the key policy responses to the HIV/AIDS epidemic in Ethiopia. However, the utilization of VCT has been low in the rural areas of the country. Understanding factors influencing the utilization of VCT provides information for the design of context based appropriate strategies that aim to improve utilization. This study examined the effects of socio-demographic and behavioral factors, and health service characteristics on the uptake of VCT among rural adults in Ethiopian.

Methods/design

This study was designed as a cross sectional study. Data from 11,919 adults (6278 women aged 15–49 years and 5641 men aged 15–59 years) residing in rural areas of Ethiopia who participated in a national health extension program evaluation were used for this study. The participants were selected from ten administrative regions using stratified multi-stage cluster sampling. Multivariate logistic regression analysis was performed accounting for factors associated with the use of VCT service.

Results

Overall, men (28 %) were relatively more likely to get tested for HIV than women (23.7 %) through VCT. Rural men and women who were young and better educated, who perceived having small risk of HIV infection, who had comprehensive knowledge, no stigmatization attitude and discussed about HIV/AIDS with their partner, and model-family were more likely to undergone VCT. Regional state was also strongly associated with VCT utilization in both men and women. Rural women who belonged to households with higher socio-economic status, non-farming occupation, female-headed household and located near health facility, and who visited health extension workers and participated in community conversation were more likely to use VCT. Among men, agrarian lifestyle was associated with VCT use.

Conclusions

Utilization of VCT in the rural communities is low, and socio-economic, behavioral and health service factors influence its utilization. For increasing the utilization of VCT service in rural areas, there is a need to target the less educated, women, poor and farming families with a focus on improving knowledge and reducing HIV/AIDS related stigma. Strategy should include promoting partner and community conversations, accelerating model-family training, and using alternative modes of testing.

Use of Balanced Scorecard Methodology for Performance Measurement of the Health Extension Program in Ethiopia

In 2004, Ethiopia introduced a community-based Health Extension Program to deliver basic and essential health services. We developed a comprehensive performance scoring methodology to assess the performance of the program. A balanced scorecard with six domains and 32 indicators was developed. Data collected from 1,014 service providers, 433 health facilities, and 10,068 community members sampled from 298 villages were used to generate weighted national, regional, and agroecological zone scores for each indicator. The national median indicator scores ranged from 37% to 98% with poor performance in commodity availability, workforce motivation, referral linkage, infection prevention, and quality of care. Indicator scores showed significant difference by region (P < 0.001). Regional performance varied across indicators suggesting that each region had specific areas of strength and deficiency, with Tigray and the Southern Nations, Nationalities and Peoples Region being the best performers while the mainly pastoral regions of Gambela, Afar, and Benishangul-Gumuz were the worst. The findings of this study suggest the need for strategies aimed at improving specific elements of the program and its performance in specific regions to achieve quality and equitable health services.

Human resource development for a community-based health extension program: a case study from Ethiopia

INTRODUCTION

Ethiopia is one of the sub-Saharan countries most affected by high disease burden, aggravated by a shortage and imbalance of human resources, geographical distance, and socioeconomic factors. In 2004, the government introduced the Health Extension Program (HEP), a primary care delivery strategy, to address the challenges and achieve the World Health Organization Millennium Development Goals (MDGs) within a context of limited resources.

CASE DESCRIPTION

The health system was reformed to create a platform for integration and institutionalization of the HEP with appropriate human capacity, infrastructure, and management structures. Human resources were developed through training of female health workers recruited from their prospective villages, designed to limit the high staff turnover and address gender, social and cultural factors in order to provide services acceptable to each community. The service delivery modalities include household, community and health facility care. Thus, the most basic health post infrastructure, designed to rapidly and cost-effectively scale up HEP, was built in each village. In line with the country's decentralized management system, the HEP service delivery is under the jurisdiction of the district authorities.

DISCUSSION AND EVALUATION

The nationwide implementation of HEP progressed in line with its target goals. In all, 40 training institutions were established, and over 30,000 Health Extension Workers have been trained and deployed to approximately 15,000 villages. The potential health service coverage reached 92.1% in 2011, up from 64% in 2004. While most health indicators have improved, performance in skilled delivery and postnatal care has not been satisfactory. While HEP is considered the most important institutional framework for achieving the health MDGs in Ethiopia, quality of service, utilization rate, access and referral linkage to emergency obstetric care, management, and evaluation of the program are the key challenges that need immediate attention.

CONCLUSIONS

This article describes the strategies, human resource developments, service delivery modalities, progress in service coverage, and the challenges in the implementation of the HEP. The Ethiopian approach of revitalization of primary care through innovative, locally appropriate and acceptable strategies will provide important lessons to other poorly resourced countries. It is hoped that the approaches and strategies described in this paper will aid in that process.

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 comparison data.

METHODS

Village sites averaging 35,000 people were selected from rural areas across diverse agroecological zones with high baseline levels of poverty and undernutrition. Starting in 2006, simultaneous investments were made in agriculture, the environment, business development, education, infrastructure, and health in partnership with communities and local governments at an annual projected cost of US$120 per person. We assessed MDG-related progress by monitoring changes 3 years after implementation across Millenium Village sites in nine countries. The primary outcome was the mortality rate of children younger than 5 years of age. To assess plausibility and attribution, we compared changes to reference data gathered from matched randomly selected comparison sites for the mortality rate of children younger than 5 years of age. Analyses were done on a per-protocol basis. This trial is registered with ClinicalTrials.gov, number NCT01125618.

FINDINGS

Baseline levels of MDG-related spending averaged $27 per head, increasing to $116 by year 3 of which $25 was spent on health. After 3 years, reductions in poverty, food insecurity, stunting, and malaria parasitaemia were reported across nine Millennium Village sites. Access to improved water and sanitation increased, along with coverage for many maternal-child health interventions. Mortality rates in children younger than 5 years of age decreased by 22% in Millennium Village sites relative to baseline (absolute decrease 25 deaths per 1000 livebirths, p=0·015) and 32% relative to matched comparison sites (30 deaths per 1000 livebirths, p=0·033).

INTERPRETATION

An integrated multisector approach for addressing the MDGs can produce rapid declines in child mortality in the first 3 years of a long-term effort in rural sub-Saharan Africa.

FUNDING

UN Human Security Trust Fund, the Lenfest Foundation, Bill & Melinda Gates Foundation, and Becton Dickinson.

Confirmed vivax resistance to chloroquine and effectiveness of artemether-lumefantrine for the treatment of vivax malaria in Ethiopia

Chloroquine (CQ) is still the drug of choice for the treatment of vivax malaria in Ethiopia, whereas artemether-lumefantrine (AL) is for falciparum malaria. In this setting, clinical malaria cases are treated with AL. This necessitated the need to assess the effectiveness of AL for the treatment of Plasmodium vivax with CQ as a comparator. A total of 57 (80.3%) and 75 (85.2%) cases treated with CQ or AL, respectively, completed the study in an outpatient setting. At the end of the follow-up period of 28 days, a cumulative incidence of treatment failure of 7.5% (95% confidence interval [CI] = 2.9-18.9%) for CQ and 19% (95% CI = 11-31.6%) for AL was detected. CQ resistance was confirmed in three of five CQ treatment failures cases. The effectiveness of AL seems lower than CQ; however, the findings were not conclusive, because the AL evening doses were not supervised.

Therapeutic efficacy of chloroquine and chloroquine plus primaquine for the treatment of Plasmodium vivax in Ethiopia

Plasmodium vivax is the second most important cause of morbidity in Ethiopia. There is, however, little information on P. vivax resistance to chloroquine and chloroquine plus primaquine treatment although these drugs have been used as the first line treatment for over 50 years. We assessed the efficacy of standard chloroquine and chloroquine plus primaquine treatment for P. vivax infections in a randomized open-label comparative study in Debre Zeit and Nazareth in East Shoa, Ethiopia. A total of 290 patients with microscopically confirmed P. vivax malaria who presented to the outpatient settings of the two laboratory centers were enrolled: 145 patients were randomized to receive CQ and 145 to receive CQ+PQ treatment. Participants were followed-up for 28-157 days according to the WHO procedures. There were 12 (6.5%) lost to follow-up patients and 9 (3.1%) withdrawals. In all, 96% (277/290) of patients were analysed at day 28. Baseline characteristics were similar in all treatment groups. In all, 98.6% (275/277) of patients had cleared their parasitemia on day 3 with no difference in mean parasite clearance time between regimens (48.34+/-17.68, 50.67+/-15.70 h for the CQ and CQ+PQ group, respectively, P=0.25). The cumulative incidence of therapeutic failure at day 28 by a life-table analysis method was 5.76% (95% CI: 2.2-14.61) and 0.75% (95% CI: 0.11-5.2%) in the CQ and CQ+PQ group, respectively (P=0.19). The relapse rate was 8% (9/108) for the CQ group and 3% (4/132) for the comparison group (P=0.07). The cumulative risk of relapse at day 157 by a life-table method was 61.8% (95% CI: 20.1-98.4%) in the CQ group, compared with 26.3% (95% CI: 7.5-29.4%) in the CQ+PQ group (P=0.0038). The study confirms the emergence of CQ and PQ resistance/treatment failure in P. vivax malaria in Ethiopia. Although treatment failures were detected, they were similar between the treatment groups. We recommend regular monitoring and periodic evaluation of the efficacy of these antimalarial drugs in systematically selected sentinel sites to detect further development of resistance and to make timely national antimalarial drug policy changes.

A temporal-spatial analysis of malaria transmission in Adama, Ethiopia

Urban malaria is a growing problem in Africa. Small-scale spatial studies are useful in identifying foci of malaria transmission in urban communities. A population-based cohort study comprising 8,088 individuals was conducted in Adama, Ethiopia. During a single malaria season, the Kulldorff scan statistic identified one temporally stable spatial malaria cluster within 350 m of a major Anopheles breeding site. Factors associated with malaria incidence were residential proximity to vector breeding site, poor house condition (incidence rate ratio [IRR] = 2.0, 95% confidence interval [CI] = 1.4, 2.9), and a high level of vegetation (IRR = 1.8, 95% CI = 1.0, 3.3). Maximum (IRR = 1.4, 95% CI = 1.1, 1.9) and minimum daily temperatures (degrees C; IRR = 1.3, 95% CI = 1.2, 1.5) were positively associated with malaria incidence after a 1-month delay. Rainfall was positively associated with malaria incidence after a 10-day delay. Findings support the use of small scale mapping and targeted vector control in urban malaria control programs in Africa.

Malaria in São Tomé and principe: on the brink of elimination after three years of effective antimalarial measures

In 2005, São Tomé e Príncipe began an initiative aimed at reducing malaria-related mortality to zero. The program included mass coverage with two antivector intervention methods (indoor residual spraying and long-lasting insecticidal nets), artemisinin-based combination therapy, and intermittent preventive therapy in pregnancy with sulfadoxine-pyrimethamine. At the end of 2007, three years after intensified interventions began, malaria-attributed outpatient consultations, hospitalizations, and deaths decreased by more than 85%, 80%, and 95%, respectively, in all age groups. Mean prevalence of parasitemia and splenomegaly were also significantly reduced to 2.1% (P < 0.0001) and 0.3% (P < 0.0001) after two rounds of spraying from baseline prevalences of 30.5% and 48.8%, respectively. The dramatic reduction in malaria morbidity and mortality now enable serious consideration of new goals and strategies aimed at completely interrupting malaria transmission on these islands. We report evidence of the program's impact and the feasibility of and potential strategies for eliminating malaria from São Tomé e Príncipe.

Individual and household level factors associated with malaria incidence in a highland region of Ethiopia: a multilevel analysis

Multilevel analysis was used to identify individual and household level factors associated with malaria risk in 1,367 individuals in a peri-urban area of highland Ethiopia. Living within 450 m of a major vector-breeding site accounted for 38.78% and 78.49% of between-household variance in malaria incidence in adults and children, respectively. In adults, other individual level factors associated with malaria risk were regular or recent travel to rural areas (incidence rate ratio [IRR] = 12.96; 95% confidence interval [CI] = 4.05, 41.48) and having an indoor job (IRR = 0.37; 95% CI = 0.16, 0.87). Household level factors associated with adult malaria risk were low vegetation level in compound (IRR = 0.27; 95% CI = 0.10, 0.78), tidy compound (IRR = 0.29; 95% CI = 0.12, 0.71), household use of preventive measures (IRR = 0.31; 95% CI = 0.13, 0.74), and the number of 5- to 9-year-old children in the household (IRR = 1.66; 95% CI = 1.08, 2.53). Aside from distance to the vector-breeding site, few other malaria risk factors were identified in children. Malaria interventions in highland African communities should address household level factors associated with malaria clustering.

Malaria and poverty

Malaria is one of the most important challenges to global public health. African countries south of the Sahara bear today the heaviest burden of malaria. The relationship between poverty and malaria has long been recognized but its paths are multiple and complex. Recent studies suggest that causality works both ways, trapping communities in reinforcing cycles of poverty and disease. If malaria is to be controlled or eventually eliminated, the social and economic conditions that fuel malaria transmission need to be addressed. At the same time, malaria control should be seen as a poverty reduction strategy.

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.

Estimated global resources needed to attain international malaria control goals

OBJECTIVE

To provide the international community with an estimate of the amount of financial resources needed to scale up malaria control to reach international goals, including allocations by country, year and intervention as well as an indication of the current funding gap.

METHODS

A costing model was used to estimate the total costs of scaling up a set of widely recommended interventions, supporting services and programme strengthening activities in each of the 81 most heavily affected malaria-endemic countries. Two scenarios were evaluated, using different assumptions about the effect of interventions on the needs for diagnosis and treatment. Current health expenditures and funding for malaria control were compared to estimated needs.

FINDINGS

A total of US$ 38 to 45 billion will be required from 2006 to 2015. The average cost during this period is US$ 3.8 to 4.5 billion per year. The average costs for Africa are US$ 1.7 billion and US$ 2.2 billion per year in the optimistic and pessimistic scenarios, respectively; outside Africa, the corresponding costs are US$ 2.1 billion and US$ 2.4 billion.

CONCLUSION

While these estimates should not be used as a template for country-level planning, they provide an indication of the scale and scope of resources required and can help donors to collaborate towards meeting a global benchmark and targeting funding to countries in greatest need. The analysis highlights the need for much greater resources to achieve the goals and targets for malaria control set by the international community.

Estimated global resources needed to attain international malaria control goals

OBJECTIVE

To provide the international community with an estimate of the amount of financial resources needed to scale up malaria control to reach international goals, including allocations by country, year and intervention as well as an indication of the current funding gap.

METHODS

A costing model was used to estimate the total costs of scaling up a set of widely recommended interventions, supporting services and programme strengthening activities in each of the 81 most heavily affected malaria-endemic countries. Two scenarios were evaluated, using different assumptions about the effect of interventions on the needs for diagnosis and treatment. Current health expenditures and funding for malaria control were compared to estimated needs.

FINDINGS

A total of US$ 38 to 45 billion will be required from 2006 to 2015. The average cost during this period is US$ 3.8 to 4.5 billion per year. The average costs for Africa are US$ 1.7 billion and US$ 2.2 billion per year in the optimistic and pessimistic scenarios, respectively; outside Africa, the corresponding costs are US$ 2.1 billion and US$ 2.4 billion.

CONCLUSION

While these estimates should not be used as a template for country-level planning, they provide an indication of the scale and scope of resources required and can help donors to collaborate towards meeting a global benchmark and targeting funding to countries in greatest need. The analysis highlights the need for much greater resources to achieve the goals and targets for malaria control set by the international community.

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.

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 4th-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.

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.

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.

A review of the clinical and epidemiologic burdens of epidemic malaria

The role of epidemic malaria as a distinct epidemiologic entity posing unique intervention challenges is reviewed from a global perspective. Epidemic malaria derives from particular interactions of vectors, parasites, and various environmental and anthropogenic determinants. Malaria epidemics generally afflict immunologically vulnerable populations, and their explosiveness can strain the capacity of health facilities, causing case fatality rates to increase five-fold or more during outbreaks. People of all ages remain susceptible to the full range of clinical effects. This flatter demographic profile may translate into larger economic consequences, although the full economic impact of epidemic malaria remains undefined. Specialized intervention approaches are recommended for epidemic-prone areas, including enhanced surveillance activities and intensified antivector interventions. Such considerations are particularly critical during a time when malaria epidemics are occurring more frequently in Africa and throughout the world.

Estimating the needs for artesunate-based combination therapy for malaria case-management in Africa

Because of inadequacies in national health information systems, the volumes of drugs required to support an effective policy transition toward artesunate-based combination therapy (ACT) are unknown for most African countries. A series of national surveys and population projections have been used to estimate the age-structured fever burden among 41 malaria endemic countries in Africa. Under present fever-management guidelines, commodity costs and internationally agreed coverage targets, the financial resources to meet the needs of ACT in most African countries are huge. Between US$1.6 billion and US$3.4 billion per annum must be found to give Africa the chance to consider a drug policy based on ACT. Substantial reductions in these costs would be achieved through more effective targeting of resources--only 20% of drugs would be required to manage fevers among the most at-risk pediatric patient populations. Better diagnostics would also be an important consideration for a new ACT policy in Africa.

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.

The community-based malaria control programme in Tigray, northern Ethiopia. A review of programme set-up, activities, outcomes and impact

Tigray, the northernmost state of Ethiopia, has a population of 3.5 million, 86% rural, and 56% living in malarious areas. In 1992 a Community-Based Malaria Control Programme was established to provide region-wide and sustained access to early diagnosis and treatment of malaria at the village level. 735 volunteer community health workers (CHWs) serve 2,327 villages with a population of 1.74 million, treating an average of 489,378 patients yearly from 1994 to 1997. Recognition of clinical malaria is similar for CHWs and health staff at clinics where there is no access to microscopy. In 1996 a pilot community-financing scheme of insecticide-treated bednets was well accepted, but re-impregnation rates fell in 1998 because of war-related social upheaval. Indicators from health institutions show a progressive increase in malaria morbidity from 1994 to 1998. Repeated mortality surveys show a 40% reduction in death rates in under-5 children from 1994 to 1996 and a 10% increase from 1996 to 1998. These trends may be related to increased malaria transmission with water resources development, increased seasonal labour migration to malarious lowlands, prolongation of the transmission season with climate changes, and increasing chloroquine resistance throughout Ethiopia. Progressive extension of CHW services to ensure better coverage of women, children, migrant workers and communities near water development projects, change to first-line treatment with sulfadoxine-pyrimethamine, extension of the impregnated bednet initiative, and development of a regional warning system for epidemics should result in a greater impact on morbidity and mortality.

Opportunities, problems and perspectives for malaria control in sub-Saharan Africa

Environments conducive to high malaria transmission and widespread poverty are at the roots of the 'malaria giant', which affects 46 countries in Africa. The recent interest in and momentum of work on malaria, in endemic countries and the international community, is unprecedented and opens new perspectives for controlling the disease. Significant steps included: (i) the allocation of US$20 million by WHO for accelerated implementation of malaria control in 34 African countries in 1997-98; (ii) the Declaration on Malaria by the Heads of States of the Organization of African Unity and the establishment of the African Initiative for Malaria Control in 1997; (iii) the concomitant mobilisation of the research community in the Multilateral Initiative on Malaria; (iv) the G8 Summit in 1998 in Birmingham asking for higher commitment to malaria control, particularly in Africa; and (v) the Roll Back Malaria initiative set as a WHO priority project in 1998. However, experiences have proved the alarming 'resilience' of the malaria system in Africa, showing devastating consequences when malaria returns to the original levels after intensive control is interrupted. Effective malaria control in Africa requires long-term action, firmly rooted in the social development of the country.

Community-based malaria control in Tigray, northern Ethiopia

Community-based control activities have been a major component of the Tigray regional malaria control programme since 1992. A team of 735 volunteer community health workers treat on average 60,000 clinical malaria cases monthly during the high malaria transmission season. Ensuring access for the rural population to early diagnosis and treatment has contributed to a significant decrease in death rate in under-five children at the village level from 1994 to 1996. Mapping and geographic information system (GIS) technologies have been introduced to support planning for control by assessment of community-based coverage. With further development, GIS will be used in stratification, and to assess the impact of water resources development on malaria transmission and intensity.

Malaria, schistosomiasis, and intestinal helminths in relation to microdams in Tigray, northern Ethiopia

A survey was undertaken in Tigray, Northern Ethiopia, to assess the prevalence of malaria, schistosomiasis, and intestinal helminths in relation to microdams. The survey took place from March to June 1995, during the dry season, at 41 microdams. At each site the village nearest the dam (within thirty minutes walk) was selected, ten households were randomly chosen, and all family members were examined for malaria and intestinal parasites. The overall study sample was 2271 people, of all age groups. Plasmodium falciparum infection was documented in four villages (at 10% of microdams); prevalence was 1.2% (range 0-20% by village). Larvae of Anopheles gambiae s.l. were found at one microdam. Infection with intestinal schistosomiasis was documented in 20 villages (at 49% of microdams), and one third of those infected had moderate to heavy infections. Biomphalaria species, the intermediate host snails of Schistosoma mansoni, were found at 16 microdams (39%), and snails infected by mammalian cercariae were found in one locality. Infections with soil-transmitted nematodes were prevalent: hookworm was detected in more than two thirds of the villages, and Ascaris lumbricoides and Trichuris trichiura were present in almost half of the villages. Out of 2078 stool examinations, the prevalence of S. mansoni infection was 7.2% (range 0-48% by village), of A. lumbricoides 2.3% (range 0-31%), of T. trichiura 2.4% (range 0-21%), and of hookworm 8.9% (range 0-78%). The prevalence of malaria, S. mansoni and hookworm was higher at altitudes below 2000 metres above sea level. S. mansoni was more prevalent in microdams built more than 5 years before the survey, while T. trichiura was more prevalent at recently constructed microdams. The widespread distribution of schistosomiasis and intestinal helminths, and the presence of malaria infection during the dry season confirm that microdams create favourable conditions for the transmission of these parasitic diseases. Health safeguards must be incorporated into the planning, construction, and operation of microdams and irrigation systems in order to prevent or reduce these diseases. In areas with high prevalence, control activities should be intensified.

Community participation in malaria control in Tigray region Ethiopia

During the Ethiopian civil war from 1974 to 1991, the Tigrean People's Liberation Front established a primary health care system in Tigray in which community residents helped to plan and implement health services through health committees and community health workers (CHWs). To strengthen and update this system, a Community-Based Malaria Control Programme was initiated in 1992. The primary objectives of the Programme are to reduce malaria morbidity and mortality and to prevent malaria in pregnant women through early diagnosis and treatment of cases, chemoprophylaxis during pregnancy, and vector control by environmental management. A secondary objective is to introduce a cost-sharing scheme for eventual development of a village revolving fund. A total of 681 volunteers chosen by their communities have received malaria training and serve a rural population of 1,682319 (CHW/population ratio 1:2,500). The principal success of the programme at this stage is that a significant proportion of the rural population at risk for malaria is now being treated at the village level. During the last major transmission season from September through November 1993, each CHWs treated a mean of 45178 clinical malaria cases per month. Under-utilization of treatment services by women and children under 5 years and low chemoprophylaxis coverage of pregnant women have been documented. After focus group discussions with community members and CHWs to identify the reasons for these problems, changes in programme policies were made to improve coverage of these groups. Since 1992, considerable progress toward meeting programme objectives has been made, and continued evaluation will allow for interventions that should further strengthen the malaria control efforts in the region.

Temporal and spatial distribution of anopheline mosquitos in an Ethiopian village: implications for malaria control strategies

The spatial and temporal distribution of Anopheles gambiae mosquitos in houses in the village of Sille in Ethiopia was monitored in 1990-91. Monthly mosquito densities in over 300 houses were obtained, and the data for each month were plotted on maps, which indicated clustering of mosquitos within the village. Spatial analysis using "kriging" techniques demonstrated clustering towards the edges of the village, the pattern of which changed with time. For example, the low density of mosquitos in one area in September increased as the nearby irrigation canals dried up during the following months. Since most entomological activity occurred at the periphery of the village, focal spraying of these areas could be a cost-effective procedure. If such clustering occurs in other villages, selective control of breeding sites and indoor spraying could provide a more efficient use of limited resources than traditional total coverage.

Control of mosquito larvae in the port city of Assab by an indigenous larvivorous fish, Aphanius dispar

A randomized controlled trial was carried out in Assab under the auspices of the National Organization for the Control of Malaria and other Vectorborne Diseases of Ethiopia to assess the effectiveness of an indigenous cyprinodontid fish, Aphanius dispar, in controlling mosquito larvae, including the local malaria vector, Anopheles culicifacies adanensis. Cisterns, wells and barrels were found to be important breeding sites for the malaria vector and for culicine mosquitoes. Fish were equally effective in controlling mosquito larvae in all the types of breeding site investigated. The overall proportion of sites with fish that harboured mosquito larvae was 1.6%, ranging from 1.5 to 1.7% according to type of site, as compared to 34% in sites left unstocked, ranging from 17.9 to 60.0%. Monthly restocking of fish where necessary was found to be sufficient to maintain an adequate level of control. Stocking of larvivorous fish in wells and household water storage containers was well-accepted by the participants, who were aware of the role of the fish in malaria prevention and found the fish useful in keeping their water free of other aquatic organisms. Based on the results of this study, larvivorous fish were introduced on an operational scale for the control of malaria transmission in Assab, with the voluntary participation of the population and the collaboration of the Municipality and health authorities of Assab.

Prospects for the use of larvivorous fish for malaria control in Ethiopia: search for indigenous species and evaluation of their feeding capacity for mosquito larvae

Because of problems with drug and insecticide resistance, the National Organization for the Control of Malaria and other Vectorborne Diseases, Ethiopia, has embarked on a programme of research on alternative malaria control methods, including the use of biological control agents, such as larvivorous fish. The objectives of the study were to identify indigenous larvivorous fish species which could be potential candidates for use as biological control agents; to extend knowledge of their distribution in Ethiopia; and to conduct laboratory tests to determine their feeding capacity. An extensive search resulted in the identification of 11 larvivorous fish species indigenous to Ethiopia, including five species previously unrecorded in the country. Seven species were assessed under standard laboratory conditions for their feeding capacity on larvae of Anopheles gambiae s.l. and Culex andersoni. All species tested were efficient larvivores in the laboratory. However, their larvivorous capacity should be tested further in field trials. Based on the findings of this study, two priority areas for the assessment of biological control using larvivorous fish were identified, the port city of Assab, using the local species Aphanius dispar, and the Ogaden, south-eastern Ethiopia, using the local species Oreochromis spilurus spilurus.

A parasitological and malacological survey of schistosomiasis mansoni in the Beles Valley, northwestern Ethiopia

A survey of schistosomiasis mansoni infection was conducted in an area of northwestern Ethiopia which has been targeted for an irrigation project. The proximity of settlements to water-bodies infested with Biomphalaria pfeifferi, and used extensively for bathing and domestic purposes, indicated that the potential for transmission is high. Snails shedding S. mansoni cercariae were found in two localities. Stool specimens from a total of 7517 persons were examined, including specimens from 4915 children age 7-14 years in 29 localities, as well as from the total population of four of the more heavily infected localities. The 10-14 year age group had the highest transmission potential, in terms of prevalence (overall 25%), intensity of infection, and absolute numbers of infected individuals, suggesting that screening and chemotherapy would be most cost-effective in that age group.

Schistosoma mansoni infection in a new settlement in Metekel district, north-western Ethiopia: morbidity and side effects of treatment with praziquantel in relation to intensity of infection

A study of morbidity and side effects of treatment with praziquantel in relation to intensity of infection with Schistosoma mansoni was conducted in 406 infected individuals from a newly-settled village in Metekel, north-western Ethiopia. Each subject was submitted to a standardized medical history and abdominal palpation. The frequencies of hepatomegaly and splenomegaly were low, 2% and 3%, respectively. A positive association was found between egg load and a history of blood in the stool. Interviews on side effects were conducted on the day following treatment with praziquantel (40 mg/kg body weight). Positive correlations with egg load were found for several side effects, including abdominal pain, diarrhoea, headache, back pain, and vomiting. Unusual side effects involving swelling of various parts of the body confirm 2 previous reports from a different region in Ethiopia and should be investigated further.

Malaria diagnosis by direct observation of centrifuged samples of blood

We compared the effectiveness of malaria diagnosis by means of direct observation of centrifuged blood with that by conventional examination of Giemsa stained blood-films in a malaria clinic in Ethiopia. A commercially available, modified hematological apparatus (the QBC tube) was used for centrifugation. Red blood cells infected with diverse stages of Plasmodium falciparum and P. vivax are lighter than noninfected cells and somewhat heavier than granulocytes; thus they can readily be detected by direct inspection of UV-illuminated tubes. About 10% of infections diagnosed by direct centrifugal microscopy in a clinical setting were not detected by conventional examination of stained thick films. Diagnosis by direct centrifugation appears to be at least 8 times as sensitive as conventional microscopy when applied to serially diluted samples of malaria-infected blood. Superior sensitivity, together with the one step, solid state nature of the direct centrifugal procedure, provides important advantages for malaria diagnosis.

Characterization of Plasmodium falciparum cloned lines with respect to gametocyte production in vitro, infectivity to Anopheles mosquitoes, and transmission to Aotus monkeys

The production of gametocytes in vitro and their subsequent infectivity to mosquitoes by 3 cloned lines of Plasmodium falciparum were studied. 2 of the cloned lines, Honduras I-clone B3 and Indochina III-clone W2, produced mature gametocytes (stage V) that were infective to Anopheles mosquitoes. The third clone, Sierra Leone I-clone D6, produced gametocytes, the majority of which did not develop beyond stage III. Fully mature gametocytes of Sierra Leone I-clone D6 were not infective to mosquitoes. Sporozoites collected from An. freeborni infected with Honduras I-clone B3 were used in transmission studies. Two of three Aotus monkeys were infected after prepatent periods of 19 and 20 d, respectively. This study supports previous reports that cloned lines of P. falciparum contain the full genetic capacity to produce morphologically mature gametocytes. The transmission to Aotus monkeys has also conclusively established that biologically competent gametocytes of both sexes are produced by clones.

Chloroquine-resistant Plasmodium falciparum malaria in Ethiopia

Standard triple-dose therapy with chloroquine (25 mg base/kg) failed to clear asexual Plasmodium falciparum parasites from the blood of 22 of 98 patients infected in various parts of Ethiopia and evaluated in Addis Ababa, a malaria-free city. RI to RIII levels of resistance were demonstrated in those patients. The resistant isolates were confined to areas bordering Somalia, Kenya, and Sudan. In in-vitro tests 7 of 10 (70%) isolates were chloroquine-resistant.

Chloroquine-resistant falciparum malaria in northern Malawi

An American Peace Corps volunteer contracted chloroquine-resistant Plasmodium falciparum malaria while serving in Malawi and taking regular chloroquine prophylaxis. Resistance was confirmed by in vitro testing of his parasites for chloroquine and pyrimethamine. The possibility of Fansidar-resistant falciparum malaria was also suggested in this case. American expatriates residing in or traveling to Malawi are advised to either take both chloroquine and Fansidar, or alternatively amodiaquine or doxycycline alone. Any breakthrough of slide-proven falciparum malaria in these individuals should be seriously suspected to be chloroquine- and Fansidar-resistant malaria, and should be treated with quinine and tetracycline.

Evaluation of sporontocidal compounds using Plasmodium falciparum gametocytes produced in vitro

A test system that uses infective gametocytes from in vitro cultures was developed for evaluating the sporontocidal activity of antimalarial compounds. In evaluating the system, pyrimethamine and cycloguanil (dihydrofolate reductase inhibitors) and primaquine (8-aminoquinoline) were tested against pyrimethamine-sensitive and pyrimethamine-resistant strains of Plasmodium falciparum. The drugs were administered to Anopheles either in a blood meal containing infective gametocytes or in a noninfective meal 2-4 days later. The mosquitoes were dissected 9-10 days after they received the infective blood meal, and the sporontocidal effect of the drugs was evaluated by the number of oocysts found in the gut. Both cycloguanil and pyrimethamine had marked sporontocidal activity. The susceptibility pattern of the strains to the sporontocidal effect of pyrimethamine and cycloguanil was similar to the susceptibility of their asexual blood stages in vitro to the schizontocidal effect of the compounds. The sporontocidal effect was observed only when the compounds were administered at the same time as the infective blood meal, but not when they were given 2-4 days later. No sporontocidal activity was observed with primaquine. This system permits more reliable quantitative observations than have been possible with previous methods.

Development of an in vitro microtest for determining the susceptibility of Plasmodium falciparum to sulfadoxine-pyrimethamine: laboratory investigations and field studies in Port-au-Prince, Haiti

An in vitro microtest for assessing the susceptibility of Plasmodium falciparum to sulfadoxine-pyrimethamine (S-P) was developed following WHO guidelines. Paraaminobenzoic acid and folic acid were depleted in the culture medium used, the test wells were predosed with sulfadoxine and pyrimethamine at a constant ratio of 80:1, and the parasites were incubated for 48 hours. Optimum parasite multiplication was obtained with a 2% erythrocyte suspension in medium supplemented with 12% serum. During in vitro studies with laboratory-adapted isolates, response patterns were obtained which distinguished 3 isolates with documented in vivo sensitivity to S-P from 2 isolates with documented in vivo resistance to S-P. In addition, among the three S-P-sensitive isolates, one isolate that was pyrimethamine-resistant in vitro had a higher S-P inhibitory endpoint than 2 isolates that were pyrimethamine-sensitive in vitro. The S-P microtest was further evaluated in combined in vivo and in vitro studies in Port-au-Prince, Haiti. Twenty-six patients infected with P. falciparum were treated with standard doses of S-P, resulting in prompt clearance of parasitaemia, with no recurrence in the 24 patients who completed a 28-day follow-up period. Parallel in vitro tests with pyrimethamine alone showed 3 pyrimethamine-resistant isolates out of 22 successful tests on the patients' blood samples. In 23 successful S-P tests, the known in vivo S-P-sensitive parasites were inhibited at S-P concentrations that were generally lower for in vitro pyrimethamine-sensitive isolates than for in vitro pyrimethamine-resistant ones.